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Запитання 1 з 71
1. Запитання
Кількість балів: 1An HIV-positive patient asks you if you can tell him the chances of him progressing to symptomatic AIDS. Which one of the following tests would be most useful?
Правильно
HIV RT PCR, a nucleic acid amplification test for HIV RNA, has recently been shown to be the most valuable test for a) monitoring a patient’s progress during triple drug therapy and b) determining the chances of progression to AIDS. A viral load of 750,000 copies per ml significantly increases the chance of progression to AIDS within 5 years. The other tests listed do not accurately predict progression to AIDS. The figure below shows the basic structure of HIV including the enzyme, reverse transcriptase:
Неправильно
HIV RT PCR, a nucleic acid amplification test for HIV RNA, has recently been shown to be the most valuable test for a) monitoring a patient’s progress during triple drug therapy and b) determining the chances of progression to AIDS. A viral load of 750,000 copies per ml significantly increases the chance of progression to AIDS within 5 years. The other tests listed do not accurately predict progression to AIDS. The figure below shows the basic structure of HIV including the enzyme, reverse transcriptase:
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Запитання 2 з 71
2. Запитання
Кількість балів: 1Which of the following viruses causes an acute febrile rash and produces disease in immunocompetent children but has been associated with transient aplastic crises in persons with sickle cell disease?
Правильно
Parvovirus B 19 is the causative agent of erythema infectiosum (fifth disease). It is associated with transient aplastic crisis in persons with hereditary hemolytic anemia. In adults, it is also associated with polyarthralgia.
Неправильно
Parvovirus B 19 is the causative agent of erythema infectiosum (fifth disease). It is associated with transient aplastic crisis in persons with hereditary hemolytic anemia. In adults, it is also associated with polyarthralgia.
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Запитання 3 з 71
3. Запитання
Кількість балів: 1The latest and most effective therapy for AIDS patients includes azidothymidine (AZT), dideoxyinosine (DDI), and saquinavir or similar agents. Use of these three drugs would inhibit which of the following viral processes?
Правильно
The advent of triple therapy or a therapeutic “cocktail” has had a marked effect on AIDS patients. The combination of drugs work together as reverse transcriptive inhibitors and a protease inhibitor.
Неправильно
The advent of triple therapy or a therapeutic “cocktail” has had a marked effect on AIDS patients. The combination of drugs work together as reverse transcriptive inhibitors and a protease inhibitor.
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Запитання 4 з 71
4. Запитання
Кількість балів: 1This HIV-positive patient with a viral load of 750,000 copies of HIV RNA/ml and a total CD4 count of 50 is at an increased risk for a number of infectious diseases. For which of the following diseases is the patient at no more added risk than an immunocompetent host?
Правильно
Many patients with high viral loads do very well on triple therapy, although resistance to one or more of the agents may subsequently occur. A low CD4 count does not predict progression to AIDS but does indicate increased chance of opportunistic infection such as those listed. Kaposi’s sarcoma, which has been linked to herpesvirus type 8, pneumocystis, and mycobacterial disease are three of the most prevalent opportunistic infections. While HIV-positive patients contract pneumococcal pneumonia, they are probably at no more risk than the general population, as protection against pneumococcal disease is linked to the presence of anticapsular antibody.
Неправильно
Many patients with high viral loads do very well on triple therapy, although resistance to one or more of the agents may subsequently occur. A low CD4 count does not predict progression to AIDS but does indicate increased chance of opportunistic infection such as those listed. Kaposi’s sarcoma, which has been linked to herpesvirus type 8, pneumocystis, and mycobacterial disease are three of the most prevalent opportunistic infections. While HIV-positive patients contract pneumococcal pneumonia, they are probably at no more risk than the general population, as protection against pneumococcal disease is linked to the presence of anticapsular antibody.
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Запитання 5 з 71
5. Запитання
Кількість балів: 1Infectious mononucleosis, a viral disorder that can be debilitating, is characterized by which of the following statements?
Правильно
All of Koch’s postulates have been verified for the relationship between infectious mononucleosis and Epstein-Barr virus, a herpesvirus. However, the relationship between this virus and Burkitt’s lymphoma, sarcoid, and systemic lupus erythematosus (SLE) is less clear. Infectious mononucleosis is most common in young adults (14 to 18 years of age) and is very rare in young children. Heterophil antibody titer is helpful in diagnosis, but is not expressed as a function of clinical recovery.
Неправильно
All of Koch’s postulates have been verified for the relationship between infectious mononucleosis and Epstein-Barr virus, a herpesvirus. However, the relationship between this virus and Burkitt’s lymphoma, sarcoid, and systemic lupus erythematosus (SLE) is less clear. Infectious mononucleosis is most common in young adults (14 to 18 years of age) and is very rare in young children. Heterophil antibody titer is helpful in diagnosis, but is not expressed as a function of clinical recovery.
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Запитання 6 з 71
6. Запитання
Кількість балів: 1A tube of monkey kidney cells is inoculated with nasopharyngeal secretions. During the next 7 days, no cytopathic effects (CPEs) are observed. On the eighth day, the tissue culture is infected accidentally with a picornavirus; nevertheless, the culture does not develop CPEs. The most likely explanation of this phenomenon is that
Правильно
Rubella virus does not produce cytopathic effects (CPEs) in tissue-culture cells. Moreover, rubellainfected cells challenged with a picornavirus are resistant to subsequent infection and thus would not exhibit CPEs. Monkey kidney cells infected only with picornavirus would show CPEs.
Неправильно
Rubella virus does not produce cytopathic effects (CPEs) in tissue-culture cells. Moreover, rubellainfected cells challenged with a picornavirus are resistant to subsequent infection and thus would not exhibit CPEs. Monkey kidney cells infected only with picornavirus would show CPEs.
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Запитання 7 з 71
7. Запитання
Кількість балів: 1The clinical picture of arbovirus infection fits one of three categories: encephalitis, hemorrhagic fever, or fever with myalgia. One of the characteristics of arboviruses is that they:
Правильно
Arboviruses (arthropodborne viruses) may or may not be surrounded by a lipid envelope, although most are inactivated by lipid solvents such as ether and may contain either double-stranded or single-stranded RNA. Physicochemical studies have demonstrated a great heterogeneity among these viruses. Arboviruses cause disease in vertebrates; in humans, encephalitis is a frequent arbovirus illness. Most human infections with arbovirus, however, are asymptomatic.
Неправильно
Arboviruses (arthropodborne viruses) may or may not be surrounded by a lipid envelope, although most are inactivated by lipid solvents such as ether and may contain either double-stranded or single-stranded RNA. Physicochemical studies have demonstrated a great heterogeneity among these viruses. Arboviruses cause disease in vertebrates; in humans, encephalitis is a frequent arbovirus illness. Most human infections with arbovirus, however, are asymptomatic.
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Запитання 8 з 71
8. Запитання
Кількість балів: 1Which one of the following statements best describes interferon’s suspected mode of action in producing resistance to viral infection?
Правильно
Interferon is a protein produced by cells in response to a viral infection or certain other agents. Entering uninfected cells, interferon causes production of a second protein that alters protein synthesis. As a result of inhibition of either translation or transcription, new viruses are not assembled following infection of interferon-protected cells.
Неправильно
Interferon is a protein produced by cells in response to a viral infection or certain other agents. Entering uninfected cells, interferon causes production of a second protein that alters protein synthesis. As a result of inhibition of either translation or transcription, new viruses are not assembled following infection of interferon-protected cells.
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Запитання 9 з 71
9. Запитання
Кількість балів: 1Delta hepatitis only occurs in patients who also have either acute or chronic infection with hepatitis B virus. The delta agent is a. An incomplete hepatitis B virus b. Related to hepatitis A virus c. A hepatitis B mutant d. An incomplete RNA virus e. Hepatitis C.
Правильно
The delta agent was first described in 1977 and has recently been shown to be an incomplete RNA virus that requires HBsAg for replication. It is found most often in persons who have multiple parenteral exposures, for example, intravenous (IV) drug abusers, hemophiliacs, and multiply transfused patients.
Неправильно
The delta agent was first described in 1977 and has recently been shown to be an incomplete RNA virus that requires HBsAg for replication. It is found most often in persons who have multiple parenteral exposures, for example, intravenous (IV) drug abusers, hemophiliacs, and multiply transfused patients.
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Запитання 10 з 71
10. Запитання
Кількість балів: 1Which of the following antiviral agents is a purine nucleoside analogue that has shown promise with Lassa fever, influenza A and B, and respiratory syncytial virus (RSV)?
Правильно
As an intravenous agent, ribavirin is effective against Lassa fever in the first week of onset of the disease. It may also be administered as an aerosol that is quite useful in infants with RSV. Unlike amantadine, which is efficacious only with influenza A, ribavirin has activity against both influenza A and B if administered by aerosol in the first 24 h of onset.
Неправильно
As an intravenous agent, ribavirin is effective against Lassa fever in the first week of onset of the disease. It may also be administered as an aerosol that is quite useful in infants with RSV. Unlike amantadine, which is efficacious only with influenza A, ribavirin has activity against both influenza A and B if administered by aerosol in the first 24 h of onset.
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Запитання 11 з 71
11. Запитання
Кількість балів: 1Echoviruses are cytopathogenic human viruses that mainly infect the:
Правильно
Echoviruses were discovered accidentally during studies on poliomyelitis. They were named enteric cytopathogenic human orphan (ECHO) viruses because, at the time, they had not been linked to human disease and thus were considered “orphans.” Echoviruses now are known to infect the intestinal tract of humans; they also can cause aseptic meningitis, febrile illnesses, and the common cold. Echoviruses range in size from 24 to 30 nm in diameter and contain a core of RNA.
Неправильно
Echoviruses were discovered accidentally during studies on poliomyelitis. They were named enteric cytopathogenic human orphan (ECHO) viruses because, at the time, they had not been linked to human disease and thus were considered “orphans.” Echoviruses now are known to infect the intestinal tract of humans; they also can cause aseptic meningitis, febrile illnesses, and the common cold. Echoviruses range in size from 24 to 30 nm in diameter and contain a core of RNA.
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Запитання 12 з 71
12. Запитання
Кількість балів: 1The most sensitive test for the diagnosis of herpes simplex (HSV) meningitis in a newborn infant is:
Правильно
HSV meningitis or encephalitis is difficult to diagnose by laboratory tests as there is a low titer of virus present in the CSF. Neonatal HSV infects the child during the birth process. While culture, Tzanck smear, and even antibody tests may be useful in adults, particularly those with HSV-rich lesions, they are not useful for CSF testing. Only PCR is sensitive enough to detect HSV DNA in the CSF. Once diagnosed rapidly, HSV encephalitis or meningitis can be treated with acyclovir.
Неправильно
HSV meningitis or encephalitis is difficult to diagnose by laboratory tests as there is a low titer of virus present in the CSF. Neonatal HSV infects the child during the birth process. While culture, Tzanck smear, and even antibody tests may be useful in adults, particularly those with HSV-rich lesions, they are not useful for CSF testing. Only PCR is sensitive enough to detect HSV DNA in the CSF. Once diagnosed rapidly, HSV encephalitis or meningitis can be treated with acyclovir.
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Запитання 13 з 71
13. Запитання
Кількість балів: 1Acute hemorrhagic conjunctivitis (AHC) is a contagious ocular infection characterized by pain, swelling of the eyelids, and subconjunctival hemorrhages. AHC has been reported to be caused by which of the following viruses?
Правильно
Enterovirus and Coxsackievirus A can be recovered from conjunctival scrapings of patients with acute hemorrhagic conjunctivitis (AHC) during the first 3 days of illness. Isolation rates are somewhat higher for enterovirus than Coxsackievirus. Less than 5% of throat swab or fecal specimens have been positive for either virus.
Неправильно
Enterovirus and Coxsackievirus A can be recovered from conjunctival scrapings of patients with acute hemorrhagic conjunctivitis (AHC) during the first 3 days of illness. Isolation rates are somewhat higher for enterovirus than Coxsackievirus. Less than 5% of throat swab or fecal specimens have been positive for either virus.
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Запитання 14 з 71
14. Запитання
Кількість балів: 1The serum of a newborn infant reveals a 1:32 cytomegalovirus (CMV) titer. The child is clinically asymptomatic. Which of the following courses of action would be advisable?
Правильно
Clinical manifestations of cytomegalovirus (CMV) infection may not be readily apparent at birth. Thus, in a newborn infant with a 1:32 titer of CMV, it is necessary to determine whether the antibodies were passed transplacentally from the mother (these antibodies would be IgG) or produced by the fetus in response to an in utero infection (IgM). A newborn infant who is infected excretes large numbers of virus particles in the urine and, therefore, places other neonates at risk for contracting CMV disease.
Неправильно
Clinical manifestations of cytomegalovirus (CMV) infection may not be readily apparent at birth. Thus, in a newborn infant with a 1:32 titer of CMV, it is necessary to determine whether the antibodies were passed transplacentally from the mother (these antibodies would be IgG) or produced by the fetus in response to an in utero infection (IgM). A newborn infant who is infected excretes large numbers of virus particles in the urine and, therefore, places other neonates at risk for contracting CMV disease.
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Запитання 15 з 71
15. Запитання
Кількість балів: 1A 3-year-old child presents at the physician’s office with symptoms of coryza, conjunctivitis, low-grade fever, and Koplik’s spots. The causative agent of this disease belongs to which group of viruses?
Правильно
Koplik’s spots are pathognomonic for measles. The measles virus is a paramyxovirus. In industrialized countries, vaccination has reduced the importance of this childhood infection (although U.S. incidence increased in 1989 and 1990). In developing countries, however, measles is a major killer of young children. In America, most states now require proof of immunity before school enrollment, and this has reduced the incidence of disease.
Неправильно
Koplik’s spots are pathognomonic for measles. The measles virus is a paramyxovirus. In industrialized countries, vaccination has reduced the importance of this childhood infection (although U.S. incidence increased in 1989 and 1990). In developing countries, however, measles is a major killer of young children. In America, most states now require proof of immunity before school enrollment, and this has reduced the incidence of disease.
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Запитання 16 з 71
16. Запитання
Кількість балів: 1One of the most common sexually transmitted diseases that may lead to cervical carcinoma is caused by which of the following viruses?
Правильно
Human papillomavirus (HPV) is the cause of genital warts. It is one of the most pervasive of all the sexually transmitted diseases. There is no specific cure or vaccine. There are multiple serotypes of papillomavirus and some serotypes are linked to cervical cancer. New techniques for molecular diagnosis of HPV show promise for rapid and sensitive detection and perhaps more aggressive treatment.
Неправильно
Human papillomavirus (HPV) is the cause of genital warts. It is one of the most pervasive of all the sexually transmitted diseases. There is no specific cure or vaccine. There are multiple serotypes of papillomavirus and some serotypes are linked to cervical cancer. New techniques for molecular diagnosis of HPV show promise for rapid and sensitive detection and perhaps more aggressive treatment.
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Запитання 17 з 71
17. Запитання
Кількість балів: 1Which virus is the leading cause of the croup syndrome in young children and, when infecting mammalian cells in culture, will hemabsorb red blood cells?
Правильно
Parainfluenza viruses are important causes of respiratory diseases in infants and young children. The spectrum of disease caused by these viruses ranges from a mild febrile cold to croup, bronchiolitis, and pneumonia. Parainfluenza viruses contain RNA in a nucleocapsid encased within an envelope derived from the host cell membrane. Infected mammalian cell culture will hemabsorb red blood cells owing to viral hemagglutinin on the surface of the cell.
Неправильно
Parainfluenza viruses are important causes of respiratory diseases in infants and young children. The spectrum of disease caused by these viruses ranges from a mild febrile cold to croup, bronchiolitis, and pneumonia. Parainfluenza viruses contain RNA in a nucleocapsid encased within an envelope derived from the host cell membrane. Infected mammalian cell culture will hemabsorb red blood cells owing to viral hemagglutinin on the surface of the cell.
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Запитання 18 з 71
18. Запитання
Кількість балів: 1A nurse develops clinical symptoms consistent with hepatitis. She recalls sticking herself with a needle approximately 4 months before after drawing blood from a patient. Serologic tests for HBsAg, antibodies to HBsAg, and hepatitis A virus (HAV) are all negative; however, she is positive for IgM core antibody. The nurse:
Правильно
In a small number of patients with acute hepatitis B infection, HBsAg can never be detected. In others, HBsAg becomes negative before the onset of the disease or before the end of the clinical illness. In such patients with acute hepatitis, hepatitis B virus infection may only be established by the presence of antihepatitis B core IgM (anti-HBc IgM), a rising titer of anti-HBc, or the subsequent appearance of anti-HBsAg.
Неправильно
In a small number of patients with acute hepatitis B infection, HBsAg can never be detected. In others, HBsAg becomes negative before the onset of the disease or before the end of the clinical illness. In such patients with acute hepatitis, hepatitis B virus infection may only be established by the presence of antihepatitis B core IgM (anti-HBc IgM), a rising titer of anti-HBc, or the subsequent appearance of anti-HBsAg.
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Запитання 19 з 71
19. Запитання
Кількість балів: 1Adults who have had varicella as children occasionally suffer a recurrent form of the disease, shingles. The agent causing these diseases is a member of which of the following viral families?
Правильно
Varicella-zoster virus, a member of the herpesvirus group, causes a usually mild, self-limited in children. Recurrent disease in adults who possess circulating antibody against varicella-zoster virus may be more severe and cause an inflammatory reaction in the sensory ganglia of spinal or cranial nerves. This disease, shingles, appears to result from the reactivation (by trauma or other stimuli) of latent varicella-zoster virus.
Неправильно
Varicella-zoster virus, a member of the herpesvirus group, causes a usually mild, self-limited in children. Recurrent disease in adults who possess circulating antibody against varicella-zoster virus may be more severe and cause an inflammatory reaction in the sensory ganglia of spinal or cranial nerves. This disease, shingles, appears to result from the reactivation (by trauma or other stimuli) of latent varicella-zoster virus.
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Запитання 20 з 71
20. Запитання
Кількість балів: 1Rhinovirus is primarily transmitted by:
Правильно
Rhinovirus is a major cause of the common cold. The primary mode of transmission is the contact of contaminated hands, fingers, or fomites with the conjunctiva or nasal epithelium. While several studies have shown no evidence of aerosol transmission, a study by Dick and associates in 1986 did show aerosol transmission can occur. This is not, however, the main mode of transmission.
Неправильно
Rhinovirus is a major cause of the common cold. The primary mode of transmission is the contact of contaminated hands, fingers, or fomites with the conjunctiva or nasal epithelium. While several studies have shown no evidence of aerosol transmission, a study by Dick and associates in 1986 did show aerosol transmission can occur. This is not, however, the main mode of transmission.
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Запитання 21 з 71
21. Запитання
Кількість балів: 1The presence of Negri inclusion bodies in host cells is characteristic of:
Правильно
The definitive diagnosis of rabies in humans is based on the finding of Negri bodies, which are cytoplasmic inclusions in the nerve cells of the spinal cord and brain, especially in the hippocampus. Negri bodies are eosinophilic and generally spherical in shape; several may appear in a given cell. Negri bodies, although pathognomonic for rabies, are not found in all cases of the disease.
Неправильно
The definitive diagnosis of rabies in humans is based on the finding of Negri bodies, which are cytoplasmic inclusions in the nerve cells of the spinal cord and brain, especially in the hippocampus. Negri bodies are eosinophilic and generally spherical in shape; several may appear in a given cell. Negri bodies, although pathognomonic for rabies, are not found in all cases of the disease.
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Запитання 22 з 71
22. Запитання
Кількість балів: 1Kuru is a fatal disease of certain New Guinea natives and is characterized by tremors and ataxia; Creutzfeldt-Jakob disease (CJD) is characterized by both ataxia and dementia. These diseases are thought to be caused by:
Правильно
Kuru and CreutzfeldtJakob disease (CJD) are similar but not identical diseases with very different epidemiology. Kuru is prevalent among certain tribes in New Guinea who practiced ritual cannibalism by eating the brains of the departed. CJD is found worldwide and has been transmitted by corneal transplants and in pituitary hormone preparations. There is some association between CJD and Mad Cow Disease in England. Prions are unconventional selfreplicating proteins, sometimes called amyloid. It is now thought that CJD, Kuru, and animal diseases such as scrapie, visna, and bovine spongiform encephalopathy (Mad Cow Disease) are caused by prions.
Неправильно
Kuru and CreutzfeldtJakob disease (CJD) are similar but not identical diseases with very different epidemiology. Kuru is prevalent among certain tribes in New Guinea who practiced ritual cannibalism by eating the brains of the departed. CJD is found worldwide and has been transmitted by corneal transplants and in pituitary hormone preparations. There is some association between CJD and Mad Cow Disease in England. Prions are unconventional selfreplicating proteins, sometimes called amyloid. It is now thought that CJD, Kuru, and animal diseases such as scrapie, visna, and bovine spongiform encephalopathy (Mad Cow Disease) are caused by prions.
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Запитання 23 з 71
23. Запитання
Кількість балів: 1According to recommendations issued by the U.S. Public Health Service, which of the following statements regarding vaccination against smallpox is true?
Правильно
Routine vaccination of infants and children for smallpox has been discontinued in the United States, both because the risk of contracting the disease is so low and because the complications of smallpox vaccination, including generalized vaccinia eruption, postvaccinal encephalitis, and fetal vaccinia, are significant. Owing to the extremely effective eradication of smallpox worldwide by the World Health Organization, U.S. citizens traveling abroad no longer require vaccination. Pregnancy, immune deficiencies, and eczema and other chronic dermatitides are contraindications to smallpox vaccination.
Неправильно
Routine vaccination of infants and children for smallpox has been discontinued in the United States, both because the risk of contracting the disease is so low and because the complications of smallpox vaccination, including generalized vaccinia eruption, postvaccinal encephalitis, and fetal vaccinia, are significant. Owing to the extremely effective eradication of smallpox worldwide by the World Health Organization, U.S. citizens traveling abroad no longer require vaccination. Pregnancy, immune deficiencies, and eczema and other chronic dermatitides are contraindications to smallpox vaccination.
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Запитання 24 з 71
24. Запитання
Кількість балів: 1Hepatitis D virus (delta agent) is a defective virus that can replicate only in cells already infected with which of the following viruses?
Правильно
Hepatitis D virus is a defective virus with an RNA genome and a hepatitis B surface antigen envelope. Two types of HDV infection occur: simultaneous HDV and HBV infection, or HDV superinfection with chronic HBV infection. Diagnosis is made by demonstrating IgM or IgG antibodies, or both.
Неправильно
Hepatitis D virus is a defective virus with an RNA genome and a hepatitis B surface antigen envelope. Two types of HDV infection occur: simultaneous HDV and HBV infection, or HDV superinfection with chronic HBV infection. Diagnosis is made by demonstrating IgM or IgG antibodies, or both.
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Запитання 25 з 71
25. Запитання
Кількість балів: 1A hospital worker is found to have hepatitis B surface antigen. Subsequent tests reveal the presence of e antigen as well. The worker most likely:
Правильно
The e antigen seems to be related to the Dane particle, which is presumed to be the intact hepatitis B virus. Possession of the e antigen suggests active disease and, thus, an increased risk of transmission of hepatitis to others. HBsAg and e antigen are components of hepatitis B and are not shared by other hepatitis viruses.
Неправильно
The e antigen seems to be related to the Dane particle, which is presumed to be the intact hepatitis B virus. Possession of the e antigen suggests active disease and, thus, an increased risk of transmission of hepatitis to others. HBsAg and e antigen are components of hepatitis B and are not shared by other hepatitis viruses.
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Запитання 26 з 71
26. Запитання
Кількість балів: 1Alphavirus causes which one of the following viral diseases?
Правильно
St. Louis encephalitis, yellow fever, and dengue are caused by flaviviruses. Western equine encephalitis is caused by an alphavirus. Laboratory diagnosis is usually made by demonstration of a fourfold rise in specific antibody titer in paired sera.
Неправильно
St. Louis encephalitis, yellow fever, and dengue are caused by flaviviruses. Western equine encephalitis is caused by an alphavirus. Laboratory diagnosis is usually made by demonstration of a fourfold rise in specific antibody titer in paired sera.
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Запитання 27 з 71
27. Запитання
Кількість балів: 1Several antiviral compounds have been developed during the last decade. One such compound is ribavirin, a synthetic nucleoside structurally related to guanosine. Ribavirin therapy has been successfully used against:
Правильно
Ribavirin is effective to varying degrees against several RNA- and DNA-containing viruses in vitro. It has been approved for aerosol treatment of respiratory syncytial virus infections in infants. Intravenous administration has proved effective in treating Lassa fever.
Неправильно
Ribavirin is effective to varying degrees against several RNA- and DNA-containing viruses in vitro. It has been approved for aerosol treatment of respiratory syncytial virus infections in infants. Intravenous administration has proved effective in treating Lassa fever.
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Запитання 28 з 71
28. Запитання
Кількість балів: 1An immunocompromised person with history of seizures had an MRI that revealed a temporal lobe lesion. Brain biopsy results showed multinucleated giant cells with intranuclear inclusions. The most probable cause of the lesion is:
Правильно
Herpes simplex virus causes primary and recurrent disease. The typical skin lesion is a vesicle that contains virus particles in serous fluid. Giant multinucleated cells are typically found at the base of the herpesvirus lesion. Encephalitis, which usually involves the temporal lobe, has a high mortality rate. Severe neurologic sequelae are seen in surviving patients.
Неправильно
Herpes simplex virus causes primary and recurrent disease. The typical skin lesion is a vesicle that contains virus particles in serous fluid. Giant multinucleated cells are typically found at the base of the herpesvirus lesion. Encephalitis, which usually involves the temporal lobe, has a high mortality rate. Severe neurologic sequelae are seen in surviving patients.
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Запитання 29 з 71
29. Запитання
Кількість балів: 1Which of the following procedures or clinical signs is most specific for the diagnosis of infectious mononucleosis caused by the Epstein-Barr virus?
Правильно
Contact with infected secretions such as saliva can result in infection with EBV, thus the term kissing disease. Laboratory diagnosis of EBV-induced infectious mononucleosis is usually determined by presence of atypical lymphocytes, heterophile antibodies, or specific antiviral antibodies such as VCA (viral capsid antibody).
Неправильно
Contact with infected secretions such as saliva can result in infection with EBV, thus the term kissing disease. Laboratory diagnosis of EBV-induced infectious mononucleosis is usually determined by presence of atypical lymphocytes, heterophile antibodies, or specific antiviral antibodies such as VCA (viral capsid antibody).
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Запитання 30 з 71
30. Запитання
Кількість балів: 1An obstetrician sees a pregnant patient who was exposed to rubella virus in the eighteenth week of pregnancy. She does not remember getting a rubella vaccination. The best immediate course of action is to:
Правильно
The highest risk of fetal infection with rubella occurs during the first trimester. In seronegative patients, the risk of infection exceeds 90%. However, before other measures (such as termination of pregnancy) are considered, a rubella immune status must be performed. A rubella titer of 1:10 is protective.
Неправильно
The highest risk of fetal infection with rubella occurs during the first trimester. In seronegative patients, the risk of infection exceeds 90%. However, before other measures (such as termination of pregnancy) are considered, a rubella immune status must be performed. A rubella titer of 1:10 is protective.
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Запитання 31 з 71
31. Запитання
Кількість балів: 1Mad Cow Disease has been highly publicized in Great Britain. This disease, which is similar to scrapie, is caused by:
Правильно
Mad Cow Disease is related to both scrapie in sheep and bovine spongiform encephalopathy virus. The fear in Great Britain is the potential for acquiring Creutzfeldt-Jakob disease, which is a slowly progressive neurodegenerative disease. Theoretically, such acquisition could be through ingestion of beef from infected cows. A prion consists of protein material without nucleic acid. While related to a virus, a prion is a proteinaceous infectious particle that replicates within cells.
Неправильно
Mad Cow Disease is related to both scrapie in sheep and bovine spongiform encephalopathy virus. The fear in Great Britain is the potential for acquiring Creutzfeldt-Jakob disease, which is a slowly progressive neurodegenerative disease. Theoretically, such acquisition could be through ingestion of beef from infected cows. A prion consists of protein material without nucleic acid. While related to a virus, a prion is a proteinaceous infectious particle that replicates within cells.
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Запитання 32 з 71
32. Запитання
Кількість балів: 1A patient has all the gastrointestinal symptoms of infection with hepatitis A virus (HAV), yet all the tests for HAV-IgG and HAV-IgM are nonreactive. A possible cause of this infection is:
Правильно
Hepatitis E virus (HEV) is a single-stranded RNA virus. It is transmitted enterically, and the disease is often referred to as enteric hepatitis C. There is no test for HEV routinely available. Diagnosis is clinical and also one of exclusion.
Неправильно
Hepatitis E virus (HEV) is a single-stranded RNA virus. It is transmitted enterically, and the disease is often referred to as enteric hepatitis C. There is no test for HEV routinely available. Diagnosis is clinical and also one of exclusion.
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Запитання 33 з 71
33. Запитання
Кількість балів: 1A 70-year-old nursing home patient refused the influenza vaccine and subsequently developed influenza. She died of acute pneumonia 1 week after contracting the “flu.” The most common cause of acute postinfluenzal pneumonia is:
Правильно
Staphylococcus aureus is the most common cause of postinfluenzal secondary bacterial pneumonia. It most often affects the elderly, although patients of any age may be afflicted. The pneumococcus as well as group A streptococci and Haemophilus influenzae may also cause pneumonia.
Неправильно
Staphylococcus aureus is the most common cause of postinfluenzal secondary bacterial pneumonia. It most often affects the elderly, although patients of any age may be afflicted. The pneumococcus as well as group A streptococci and Haemophilus influenzae may also cause pneumonia.
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Запитання 34 з 71
34. Запитання
Кількість балів: 1Hantavirus is an emerging pathogen that is best described by which of the following statements?
Правильно
In 1993, an outbreak of a fatal respiratory disease occurred in the southwestern United States. This disease is caused by a Hantavirus endemic in deer mice. It is not transmitted from person to person. The mortality rate is 60%. Ribavirin has been used but is not effective. A vaccine is not available.
Неправильно
In 1993, an outbreak of a fatal respiratory disease occurred in the southwestern United States. This disease is caused by a Hantavirus endemic in deer mice. It is not transmitted from person to person. The mortality rate is 60%. Ribavirin has been used but is not effective. A vaccine is not available.
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Запитання 35 з 71
35. Запитання
Кількість балів: 1Erythema infectiosum (fifth disease), a self-limited disease of children, is caused by:
Правильно
Parvovirus B19 causes the common disease erythema infectiosum, characterized by a “slapped cheek” rash. Called fifth disease, it is the fifth childhood rash disease; the other four are measles, rubella, scarlet fever, and roseola.
Неправильно
Parvovirus B19 causes the common disease erythema infectiosum, characterized by a “slapped cheek” rash. Called fifth disease, it is the fifth childhood rash disease; the other four are measles, rubella, scarlet fever, and roseola.
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Запитання 36 з 71
36. Запитання
Кількість балів: 1Which one of the following viruses may be human tumor virus?
Правильно
Only two human viruses have been confirmed as human tumor viruses. They include human T-cell lymphoma/leukemia virus (HTLV) and papillomavirus. Others, such as EBV, HSV, and hepatitis B and C, have been implicated as tumor viruses. The virus that causes chicken pox (VZV) is not know to be oncogenic.
Неправильно
Only two human viruses have been confirmed as human tumor viruses. They include human T-cell lymphoma/leukemia virus (HTLV) and papillomavirus. Others, such as EBV, HSV, and hepatitis B and C, have been implicated as tumor viruses. The virus that causes chicken pox (VZV) is not know to be oncogenic.
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Запитання 37 з 71
37. Запитання
Кількість балів: 1Cytomegalovirus (CMV) infection is common. Which one of the following statements best characterizes CMV?
Правильно
Although infection with cytomegalovirus (CMV) is common, it only rarely causes clinically apparent disease. Lesions characteristic of infection with CMV are found in up to 10% of stillborn babies; however, CMV, which can be transmitted transplacentally, usually is not the cause of death. Children and adults with immunosuppressive problems are susceptible to active disease. In severely immunodeficient patients such as those with AIDS, CMV ocular disease may occur. The patient suffers blurring of vision or vision loss, and ophthalmic examination reveals large yellowish-white areas with flame-shaped hemorrhages. Ganciclovir is now licensed for treatment of CMV retinitis in AIDS patients.
Неправильно
Although infection with cytomegalovirus (CMV) is common, it only rarely causes clinically apparent disease. Lesions characteristic of infection with CMV are found in up to 10% of stillborn babies; however, CMV, which can be transmitted transplacentally, usually is not the cause of death. Children and adults with immunosuppressive problems are susceptible to active disease. In severely immunodeficient patients such as those with AIDS, CMV ocular disease may occur. The patient suffers blurring of vision or vision loss, and ophthalmic examination reveals large yellowish-white areas with flame-shaped hemorrhages. Ganciclovir is now licensed for treatment of CMV retinitis in AIDS patients.
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Запитання 38 з 71
38. Запитання
Кількість балів: 1Human rotaviruses are characterized by which of the following statements?
Правильно
Rotaviruses were initially identified by direct electron microscopy (EM) of duodenal mucosa of infants with gastroenteritis. Subsequent studies in several countries have shown them to be the cause of 30 to 40% of acute diarrhea in infants. They are non-lipid-containing RNA viruses with a double-shelled capsid. Although the virus has been serially propagated in human fetal intestinal organ cultures, cytopathic changes are minimal or absent; multiplication is detected by immunofluorescence. Numerous methods for rotavirus antigen detection, including radioimmunoassay, counterimmunoelectrophoresis, and enzyme-linked immunosorbent assay, have been developed and found to be about as effective as EM.
Неправильно
Rotaviruses were initially identified by direct electron microscopy (EM) of duodenal mucosa of infants with gastroenteritis. Subsequent studies in several countries have shown them to be the cause of 30 to 40% of acute diarrhea in infants. They are non-lipid-containing RNA viruses with a double-shelled capsid. Although the virus has been serially propagated in human fetal intestinal organ cultures, cytopathic changes are minimal or absent; multiplication is detected by immunofluorescence. Numerous methods for rotavirus antigen detection, including radioimmunoassay, counterimmunoelectrophoresis, and enzyme-linked immunosorbent assay, have been developed and found to be about as effective as EM.
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Запитання 39 з 71
39. Запитання
Кількість балів: 1Subacute sclerosing panencephalitis virus (SSPE) is best described by which of the following statements?
Правильно
SSPE is a late and rare manifestation of measles. It is a progressive encephalitis involving both white and gray matter. Demyelination is seen only at an advanced stage of the disease in a few cases. In 1985, viral RNA was demonstrated in brain cells from a patient with SSPE by the use of in situ hybridization.
Неправильно
SSPE is a late and rare manifestation of measles. It is a progressive encephalitis involving both white and gray matter. Demyelination is seen only at an advanced stage of the disease in a few cases. In 1985, viral RNA was demonstrated in brain cells from a patient with SSPE by the use of in situ hybridization.
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Запитання 40 з 71
40. Запитання
Кількість балів: 1Rotavirus is a double-stranded RNA virus with a double-walled capsid. Which one of the following statements best describes rotavirus?
Правильно
Rotavirus is a viral entity that is similar to Nebraska calf diarrhea virus and is thought to be a major cause of acute diarrhea in newborn infants. Three-quarters of all adults have antibodies against rotavirus; passive transfer of these antibodies to the baby, especially through the colostrum, seems to be protective. Although vaccination would be expected to be of little use to the neonate, it might effectively immunize pregnant mothers.
Неправильно
Rotavirus is a viral entity that is similar to Nebraska calf diarrhea virus and is thought to be a major cause of acute diarrhea in newborn infants. Three-quarters of all adults have antibodies against rotavirus; passive transfer of these antibodies to the baby, especially through the colostrum, seems to be protective. Although vaccination would be expected to be of little use to the neonate, it might effectively immunize pregnant mothers.
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Запитання 41 з 71
41. Запитання
Кількість балів: 1Human papillomavirus is most commonly associated with:
Правильно
Papillomavirus infects the skin or mucosa and causes benign tumors. The lesion is termed condyloma acuminatum. These tumors may undergo malignant conversion and become squamous cell carcinomas. Classification of the human papillomavirus is done by DNA hybridization, and to date 46 types have been recognized. Some types, such as 16 and 18, are more frequently associated with carcinoma, while others, such as 6 and 11, are associated with benign tumors or warts.
Неправильно
Papillomavirus infects the skin or mucosa and causes benign tumors. The lesion is termed condyloma acuminatum. These tumors may undergo malignant conversion and become squamous cell carcinomas. Classification of the human papillomavirus is done by DNA hybridization, and to date 46 types have been recognized. Some types, such as 16 and 18, are more frequently associated with carcinoma, while others, such as 6 and 11, are associated with benign tumors or warts.
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Запитання 42 з 71
42. Запитання
Кількість балів: 1Reverse transcriptase is an enzyme unique to the retroviruses. Which one of the following is a function of the enzyme reverse transcriptase?
Правильно
The replication of a retroviral genome is dependent on the reverse transcriptase enzyme, which performs a variety of functions. It builds a complementary strand of DNA for the viral RNA template; it builds a second DNA strand complementary to the previous DNA; it degrades the original RNA, leaving a DNA-DNA duplex; and, finally, it is responsible for integrating the new viral DNA hybrid into the host genome.
Неправильно
The replication of a retroviral genome is dependent on the reverse transcriptase enzyme, which performs a variety of functions. It builds a complementary strand of DNA for the viral RNA template; it builds a second DNA strand complementary to the previous DNA; it degrades the original RNA, leaving a DNA-DNA duplex; and, finally, it is responsible for integrating the new viral DNA hybrid into the host genome.
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Запитання 43 з 71
43. Запитання
Кількість балів: 1There is considerable overlap of signs and symptoms seen in congenital and perinatal infections. In a neonate with “classic” symptoms of congenital cytomegalovirus (CMV) infection, which one of the following tests would be most useful in establishing a diagnosis?
Правильно
Presently, cytomegalovirus (CMV) is the most common cause of congenital and perinatal viral infections. Culture of the virus is a sensitive diagnostic technique; in the case of a neonate with classic symptoms, serum samples from the mother and neonate are obtained at birth. The IgM antibody titer in the infant’s serum should be higher than the mother’s titer, but they may be similar. For this reason, another sample from the infant at 1 month of age is tested simultaneously with the initial sample. The results should indicate a rise in IgM titer. Measurement of total IgM in the infant’s sera at birth is nonspecific and may show false-negative and false-positive reactions.
Неправильно
Presently, cytomegalovirus (CMV) is the most common cause of congenital and perinatal viral infections. Culture of the virus is a sensitive diagnostic technique; in the case of a neonate with classic symptoms, serum samples from the mother and neonate are obtained at birth. The IgM antibody titer in the infant’s serum should be higher than the mother’s titer, but they may be similar. For this reason, another sample from the infant at 1 month of age is tested simultaneously with the initial sample. The results should indicate a rise in IgM titer. Measurement of total IgM in the infant’s sera at birth is nonspecific and may show false-negative and false-positive reactions.
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Запитання 44 з 71
44. Запитання
Кількість балів: 1Which one of the following statements best describes the cytopathic effects of viruses on host cells?
Правильно
Viral cytopathic effects are thought to include a change in the host cell’s macromolecular synthesis and the structure of the cell membrane. Viruses may produce cytopathic changes without forming infectious virions and without replicating infectious virus, although the cytopathology is usually fatal to the cell. A particular cytopathic effect is not necessarily associated with a specific virus.
Неправильно
Viral cytopathic effects are thought to include a change in the host cell’s macromolecular synthesis and the structure of the cell membrane. Viruses may produce cytopathic changes without forming infectious virions and without replicating infectious virus, although the cytopathology is usually fatal to the cell. A particular cytopathic effect is not necessarily associated with a specific virus.
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Запитання 45 з 71
45. Запитання
Кількість балів: 1A 17-year-old girl presents with cervical lymphadenopathy, fever, and pharyngitis. Infectious mononucleosis is suspected. The most rapid and clinically useful test to make this diagnosis is:
Правильно
With an acute case of primary infection by Epstein-Barr virus (EBV), such as infectious mononucleosis, IgM antibodies to VCA should be present. Antibodies to EBNA should be absent, as they usually appear 2 to 3 months after onset of illness. Culture is not clinically useful because it (1) requires freshly fractionated cord blood lymphocytes, (2) takes 3 to 4 weeks for completion, and (3) is reactive in the majority of seropositive patients.
Неправильно
With an acute case of primary infection by Epstein-Barr virus (EBV), such as infectious mononucleosis, IgM antibodies to VCA should be present. Antibodies to EBNA should be absent, as they usually appear 2 to 3 months after onset of illness. Culture is not clinically useful because it (1) requires freshly fractionated cord blood lymphocytes, (2) takes 3 to 4 weeks for completion, and (3) is reactive in the majority of seropositive patients.
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Запитання 46 з 71
46. Запитання
Кількість балів: 1A regimen that includes appropriately administered gamma globulin may be contraindicated in which one of the following diseases?
Правильно
A therapeutic regimen that includes appropriately administered gamma globulin is effective in the treatment of viral hepatitis A and B. Hyperimmune rabies antiserum prolongs the incubation period of rabies and allows the patient more time to mount an immune response to the vaccine. Although it is not a primary form of treatment for patients with poliomyelitis, passive immunization with pooled gamma globulin can offer adequate protection against the disease.
Неправильно
A therapeutic regimen that includes appropriately administered gamma globulin is effective in the treatment of viral hepatitis A and B. Hyperimmune rabies antiserum prolongs the incubation period of rabies and allows the patient more time to mount an immune response to the vaccine. Although it is not a primary form of treatment for patients with poliomyelitis, passive immunization with pooled gamma globulin can offer adequate protection against the disease.
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Запитання 47 з 71
47. Запитання
Кількість балів: 1Atypical lymphocytosis is most likely to be found in which one of the following diseases?
Правильно
Atypical lymphocytes are the hematologic hallmark of infectious mononucleosis with 90% or more of the circulating lymphocytes being atypical in some cases. These abnormal lymphocytes are not pathognomonic for infectious mononucleosis. They are also seen in other diseases, including cytomegalovirus infection, viral hepatitis, toxoplasmosis, rubella, mumps, and roseola.
Неправильно
Atypical lymphocytes are the hematologic hallmark of infectious mononucleosis with 90% or more of the circulating lymphocytes being atypical in some cases. These abnormal lymphocytes are not pathognomonic for infectious mononucleosis. They are also seen in other diseases, including cytomegalovirus infection, viral hepatitis, toxoplasmosis, rubella, mumps, and roseola.
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Запитання 48 з 71
48. Запитання
Кількість балів: 1A patient has arthralgia, a rash, lymphadenopathy, pneumonia but no fever. Which of the following diseases is most likely based on these symptoms?
Правильно
Dengue (breakbone fever) is caused by a group B togavirus that is transmitted by mosquitoes. The clinical syndrome usually consists of a mild systemic disease characterized by severe joint and muscle pain, headache, fever, lymphadenopathy, and a maculopapular rash. Hemorrhagic dengue, a more severe syndrome, may be prominent during some epidemics; shock and occasionally death result.
Неправильно
Dengue (breakbone fever) is caused by a group B togavirus that is transmitted by mosquitoes. The clinical syndrome usually consists of a mild systemic disease characterized by severe joint and muscle pain, headache, fever, lymphadenopathy, and a maculopapular rash. Hemorrhagic dengue, a more severe syndrome, may be prominent during some epidemics; shock and occasionally death result.
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Запитання 49 з 71
49. Запитання
Кількість балів: 1Hepatitis C (HCV) is usually a clinically mild disease, with only minimal elevation of liver enzymes. Hospitalization is unusual. Which one of the following statements best characterizes HCV?
Правильно
HCV is a positive-stranded RNA virus, tentatively classified as a flavivirus. About half of HCV patients develop chronic hepatitis. A large number of infections appear among IV drug abusers. About 90% of the cases of transfusion-associated hepatitis are thought to be caused by HCV.
Неправильно
HCV is a positive-stranded RNA virus, tentatively classified as a flavivirus. About half of HCV patients develop chronic hepatitis. A large number of infections appear among IV drug abusers. About 90% of the cases of transfusion-associated hepatitis are thought to be caused by HCV.
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Запитання 50 з 71
50. Запитання
Кількість балів: 1Which of the following markers is usually the first viral marker detected after hepatitis B infection?
Правильно
Advances in the serodiagnosis of viral hepatitis have been dramatic, and the findings of specific viral antigens have led to further elucidation of the course of infections. The “Australia antigen,” discovered in 1960, was first renamed hepatitis-associated antigen (HAA) and then, finally, hepatitis B surface antigen (HBsAg). It appears in the blood early after infection, before onset of acute illness, and persists through early convalescence. HBsAg usually disappears within 4 to 6 months after the start of clinical illness except in the case of chronic carriers.
Неправильно
Advances in the serodiagnosis of viral hepatitis have been dramatic, and the findings of specific viral antigens have led to further elucidation of the course of infections. The “Australia antigen,” discovered in 1960, was first renamed hepatitis-associated antigen (HAA) and then, finally, hepatitis B surface antigen (HBsAg). It appears in the blood early after infection, before onset of acute illness, and persists through early convalescence. HBsAg usually disappears within 4 to 6 months after the start of clinical illness except in the case of chronic carriers.
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Запитання 51 з 71
51. Запитання
Кількість балів: 1Which of the following may be the only detectable serological marker during the early convalescent phase of HBV infection (window phase)?
Правильно
The hepatitis B core antigen (HBcAg) is found within the nuclei of infected hepatocytes and not generally in the peripheral circulation except as an integral component of the Dane particle. The antibody to this antigen, anti-HBc, is present at the beginning of clinical illness. As long as there is ongoing HBV replication, there will be high titers of anti-HBc. During the early convalescent phase of an HBV infection, anti-HBc may be the only detectable serologic marker (window phase), if HBsAg is negative and antiHBsAg has not appeared.
Неправильно
The hepatitis B core antigen (HBcAg) is found within the nuclei of infected hepatocytes and not generally in the peripheral circulation except as an integral component of the Dane particle. The antibody to this antigen, anti-HBc, is present at the beginning of clinical illness. As long as there is ongoing HBV replication, there will be high titers of anti-HBc. During the early convalescent phase of an HBV infection, anti-HBc may be the only detectable serologic marker (window phase), if HBsAg is negative and antiHBsAg has not appeared.
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Запитання 52 з 71
52. Запитання
Кількість балів: 1Which one of the following markers is closely associated with HBV infectivity and DNA polymerase activity?
Правильно
Hepatitis B antigen (HBeAg) appears during the early acute phase and disappears before HBsAg is gone, although it may persist in the chronic carrier. Persons who are HBeAg-positive have higher titers of HBV and therefore are at a higher risk of transmitting the disease. HBeAg has a high correlation with DNA polymerase activity.
Неправильно
Hepatitis B antigen (HBeAg) appears during the early acute phase and disappears before HBsAg is gone, although it may persist in the chronic carrier. Persons who are HBeAg-positive have higher titers of HBV and therefore are at a higher risk of transmitting the disease. HBeAg has a high correlation with DNA polymerase activity.
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Запитання 53 з 71
53. Запитання
Кількість балів: 1Which of the following is found within the nuclei of infected hepatocytes and not usually in the peripheral circulation?
Правильно
The hepatitis B core antigen (HBcAg) is found within the nuclei of infected hepatocytes and not generally in the peripheral circulation except as an integral component of the Dane particle. The antibody to this antigen, anti-HBc, is present at the beginning of clinical illness. As long as there is ongoing HBV replication, there will be high titers of anti-HBc. During the early convalescent phase of an HBV infection, anti-HBc may be the only detectable serologic marker (window phase) if HBsAg is negative and antiHBsAg has not appeared.
Неправильно
The hepatitis B core antigen (HBcAg) is found within the nuclei of infected hepatocytes and not generally in the peripheral circulation except as an integral component of the Dane particle. The antibody to this antigen, anti-HBc, is present at the beginning of clinical illness. As long as there is ongoing HBV replication, there will be high titers of anti-HBc. During the early convalescent phase of an HBV infection, anti-HBc may be the only detectable serologic marker (window phase) if HBsAg is negative and antiHBsAg has not appeared.
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Запитання 54 з 71
54. Запитання
Кількість балів: 1Which one of the following viruses is the leading cause of congenital malformations?
Правильно
Cytomegalovirus causes cytomegalic inclusion disease (CID), especially congenital abnormalities, in neonates. Malformations include microencephaly. Seizures, deafness, jaundice, and purpura can also occur. CID is also one of the leading causes of mental retardation in the United States.
Неправильно
Cytomegalovirus causes cytomegalic inclusion disease (CID), especially congenital abnormalities, in neonates. Malformations include microencephaly. Seizures, deafness, jaundice, and purpura can also occur. CID is also one of the leading causes of mental retardation in the United States.
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Запитання 55 з 71
55. Запитання
Кількість балів: 1Orchitis, which may cause sterility, is a possible manifestation of which of the following?
Правильно
Orchitis, a complication of mumps virus infection in postpubertal males, can cause sterility if bilateral.
Неправильно
Orchitis, a complication of mumps virus infection in postpubertal males, can cause sterility if bilateral.
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Запитання 56 з 71
56. Запитання
Кількість балів: 1Traditional vaccination for the common cold is virtually impossible because there are multiple serotypes of which one of the following viruses?
Правильно
Respiratory syncytial virus (RSV) is the leading cause of pneumonia and bronchiolitis in infants. Viremia does not occur and treatment in several ill infants is aerosolized ribavirin.
Неправильно
Respiratory syncytial virus (RSV) is the leading cause of pneumonia and bronchiolitis in infants. Viremia does not occur and treatment in several ill infants is aerosolized ribavirin.
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Запитання 57 з 71
57. Запитання
Кількість балів: 1Which of the following is available and effective for hepatitis A?
Правильно
The vaccine for hepatitis A virus (HAV) is prepared from virus grown in culture and inactivated with formalin.
Неправильно
The vaccine for hepatitis A virus (HAV) is prepared from virus grown in culture and inactivated with formalin.
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Запитання 58 з 71
58. Запитання
Кількість балів: 1Patients should be vaccinated annually for influenza with which of the following vaccines?
Правильно
Influenza usually occurs in successive waves of infection with peak incidences during the winter months. If only minor antigenic drift is expected for the next influenza season, then the most recent strains of A and B viruses representative of the main antigens are included in the vaccine. Influenza vaccine consists of killed viruses.
Неправильно
Influenza usually occurs in successive waves of infection with peak incidences during the winter months. If only minor antigenic drift is expected for the next influenza season, then the most recent strains of A and B viruses representative of the main antigens are included in the vaccine. Influenza vaccine consists of killed viruses.
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Запитання 59 з 71
59. Запитання
Кількість балів: 1Which of the following best describes the presently available vaccine for hepatitis B?
Правильно
The original vaccine for hepatitis B was prepared by purifying hepatitis B surface antigen (HBsAg) from healthy HBsAg-positive carriers and treating it with viral-inactivating agents. The second-generation vaccine for hepatitis B is produced by recombinant DNA in yeast cells containing a plasmid into which the gene for HBsAg has been incorporated.
Неправильно
The original vaccine for hepatitis B was prepared by purifying hepatitis B surface antigen (HBsAg) from healthy HBsAg-positive carriers and treating it with viral-inactivating agents. The second-generation vaccine for hepatitis B is produced by recombinant DNA in yeast cells containing a plasmid into which the gene for HBsAg has been incorporated.
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Запитання 60 з 71
60. Запитання
Кількість балів: 1Lethargy, malaise, and fatigue are observed in a patient 2 weeks after eating raw hamburger at a restaurant. The most likely infectious cause is:
Правильно
Similar mononucleosis-like diseases are caused by cytomegalovirus (CMV) and Toxoplasma gondii, a parasite. CMV causes fewer than 10% of infectious mononucleosis-like diseases. CMV “mono” is primarily characterized by fatigue. Congenital infection with CMV almost always causes serious sequelae, such as retardation and hearing loss. T. gondii also causes a variety of clinical problems, among them encephalitis in AIDS patients and food poisoning from the ingestion of raw meat. Although CMV and T. gondii are relatively rare causes of infectious mononucleosis, they must be ruled out, particularly when EBV tests are nonreactive.
Неправильно
Similar mononucleosis-like diseases are caused by cytomegalovirus (CMV) and Toxoplasma gondii, a parasite. CMV causes fewer than 10% of infectious mononucleosis-like diseases. CMV “mono” is primarily characterized by fatigue. Congenital infection with CMV almost always causes serious sequelae, such as retardation and hearing loss. T. gondii also causes a variety of clinical problems, among them encephalitis in AIDS patients and food poisoning from the ingestion of raw meat. Although CMV and T. gondii are relatively rare causes of infectious mononucleosis, they must be ruled out, particularly when EBV tests are nonreactive.
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Запитання 61 з 71
61. Запитання
Кількість балів: 1Burkitt’s lymphoma is characterized by elevated “early antigen” tests with a restricted pattern of fluorescence. This disease is caused by:
Правильно
EBV causes a variety of other syndromes including Burkitt’s lymphoma, the most common childhood cancer in Africa, and nasopharyngeal carcinoma, commonly seen in China.
Неправильно
EBV causes a variety of other syndromes including Burkitt’s lymphoma, the most common childhood cancer in Africa, and nasopharyngeal carcinoma, commonly seen in China.
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Запитання 62 з 71
62. Запитання
Кількість балів: 1Which of the following is transmitted by the fecal-oral route; can be acquired from shellfish; and often causes acute jaundice, diarrhea, and liver function abnormalities?
Правильно
Неправильно
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Запитання 63 з 71
63. Запитання
Кількість балів: 1Which of the following is the second most common cause of pediatric gastroenteritis? Unlike other similar viruses, this virus causes only gastroenteritis.
Правильно
A number of viruses that cause gastroenteritis are now being recognized ( rotavirus, Norwalk virus, adenovirus, calicivirus, and astrovirus, only gastroenteritis – Adenovirus 40/41.
Неправильно
A number of viruses that cause gastroenteritis are now being recognized ( rotavirus, Norwalk virus, adenovirus, calicivirus, and astrovirus, only gastroenteritis – Adenovirus 40/41.
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Запитання 64 з 71
64. Запитання
Кількість балів: 1Which of the following is the most common cause of pediatric gastroenteritis? It is difficult to grow in cell culture but can be detected easily by immunologic methods (ELISA).
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Запитання 65 з 71
65. Запитання
Кількість балів: 1Which of the following is a cause of mild gastroenteritis? It can be transmitted by the fecal-oral route but not by food consumption.
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Запитання 66 з 71
66. Запитання
Кількість балів: 1IgM antibody to the viral particle is the method of choice for laboratory diagnosis of which one of the following hepatitis viruses?
Правильно
Detection of anti-HAV IgM in a single serum specimen obtained in the acute or convalescent stage is the quickest and most reliable method to diagnose hepatitis A infection. This antibody is usually present at onset of symptoms and may persist 3 to 6 months.
Неправильно
Detection of anti-HAV IgM in a single serum specimen obtained in the acute or convalescent stage is the quickest and most reliable method to diagnose hepatitis A infection. This antibody is usually present at onset of symptoms and may persist 3 to 6 months.
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Запитання 67 з 71
67. Запитання
Кількість балів: 1This hepatitis virus is a calicivirus. The reservoir is in pigs, and humans acquire it via the fecal-oral route.
Правильно
Hepatitis E virus is an RNA virus. Transmission is by the fecal-oral route although maternal-fetal transmission has recently been described. Prognosis is usually favorable with rare cases of fulminant HEV reported.
Неправильно
Hepatitis E virus is an RNA virus. Transmission is by the fecal-oral route although maternal-fetal transmission has recently been described. Prognosis is usually favorable with rare cases of fulminant HEV reported.
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Запитання 68 з 71
68. Запитання
Кількість балів: 1Which of the following viruses causes progressive multifocal leukoencephalopathy (PML), a disease causing demyelination in the central nervous system?
Правильно
HPV (Human papillomavirus) and polyomavirus have icosahedral capsids and DNA genomes. JC virus, a polyomavirus, was first isolated from the diseased brain of a patient with Hodgkin’s lymphoma who was dying of progressive multifocal leukoencephalopathy (PML). This demyelinating disease occurs usually in immunosuppressed persons and is the result of oligodendrocyte infection by JC virus. JC virus has also been isolated from the urine of patients suffering from demyelinating disease. Cryotherapy and laser treatment are the most popular therapies for warts, although surgery may be indicated in some cases. At the present time, there is no effective antiviral therapy for treatment of infection with polyomavirus or HPV. West Nile virus is an arbovirus. While prevalent in Europe, Africa, and the Middle East, it was not seen in the United States until the summer of 1999. It is transmitted by mosqitoes and birds, especially crows; these animals are a reservoir. WNV causes a rather mild encephalitis in humans, the exception being older patients or those who may be immunocompromised.
Неправильно
HPV (Human papillomavirus) and polyomavirus have icosahedral capsids and DNA genomes. JC virus, a polyomavirus, was first isolated from the diseased brain of a patient with Hodgkin’s lymphoma who was dying of progressive multifocal leukoencephalopathy (PML). This demyelinating disease occurs usually in immunosuppressed persons and is the result of oligodendrocyte infection by JC virus. JC virus has also been isolated from the urine of patients suffering from demyelinating disease. Cryotherapy and laser treatment are the most popular therapies for warts, although surgery may be indicated in some cases. At the present time, there is no effective antiviral therapy for treatment of infection with polyomavirus or HPV. West Nile virus is an arbovirus. While prevalent in Europe, Africa, and the Middle East, it was not seen in the United States until the summer of 1999. It is transmitted by mosqitoes and birds, especially crows; these animals are a reservoir. WNV causes a rather mild encephalitis in humans, the exception being older patients or those who may be immunocompromised.
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Запитання 69 з 71
69. Запитання
Кількість балів: 1This virus is transmitted by the same arthropod that transmits babesiosis and ehrlichiosis.
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Запитання 70 з 71
70. Запитання
Кількість балів: 1This virus is a single-stranded RNA orthomyxovirus. Annual vaccination is necessary because of antigenic drift and shift.
Правильно
Orthomyxoviruses and paramyxoviruses are RNA viruses that contain a single-stranded RNA genome. The influenza viruses belong to the orthomyxoviruses. They cause acute respiratory tract infections that usually occur in epidemics. Isolated strains of influenza virus are named after the virus type (influenza A, B, or C) as well as the host and location of initial isolation, the year of isolation, and the antigenic designation of the hemagglutinin and neuraminidase. Both the hemagglutinin and neuraminidase are glycoproteins under separate genetic control, and because of this they can and do vary independently. The changes in these antigens are responsible for the antigenic drift characteristic of these viruses.
Неправильно
Orthomyxoviruses and paramyxoviruses are RNA viruses that contain a single-stranded RNA genome. The influenza viruses belong to the orthomyxoviruses. They cause acute respiratory tract infections that usually occur in epidemics. Isolated strains of influenza virus are named after the virus type (influenza A, B, or C) as well as the host and location of initial isolation, the year of isolation, and the antigenic designation of the hemagglutinin and neuraminidase. Both the hemagglutinin and neuraminidase are glycoproteins under separate genetic control, and because of this they can and do vary independently. The changes in these antigens are responsible for the antigenic drift characteristic of these viruses.
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Запитання 71 з 71
71. Запитання
Кількість балів: 1Megakaryocytes are minimally immunoresponsive; such cells are also known as:
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Запитання 1 з 28
1. Запитання
Кількість балів: 1What is the differential sign of adenoviral infection?
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Запитання 2 з 28
2. Запитання
Кількість балів: 1What is the differential sign of parainfluenza?
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Запитання 3 з 28
3. Запитання
Кількість балів: 1What is the differential sign of respiratory-syncytial infection?
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Запитання 4 з 28
4. Запитання
Кількість балів: 1What is the differential sign of rhinoviral infection?
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Запитання 5 з 28
5. Запитання
Кількість балів: 1When is it necessary to give antibacterial therapy in case of URT viral infections?
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Запитання 6 з 28
6. Запитання
Кількість балів: 1Choose the triad of clinical symptoms, typical for the croup syndrome:
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Запитання 7 з 28
7. Запитання
Кількість балів: 1What is the criterion of the compensated croup?
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Запитання 8 з 28
8. Запитання
Кількість балів: 1What is the criterion of the decompensated croup?
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Запитання 9 з 28
9. Запитання
Кількість балів: 1What is the indication to administer antibiotics in case of the false croup?
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Запитання 10 з 28
10. Запитання
Кількість балів: 1The parainfluenza virus belongs to:
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Запитання 11 з 28
11. Запитання
Кількість балів: 1Adenoviruses are only cultivated in:
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Запитання 12 з 28
12. Запитання
Кількість балів: 1Which virus could more reliably cause pneumonia?
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Запитання 13 з 28
13. Запитання
Кількість балів: 1Giant multinucleated cells in sputum are typical for:
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Запитання 14 з 28
14. Запитання
Кількість балів: 1What test is used for express diagnostic of acute respiratory infection?
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Запитання 15 з 28
15. Запитання
Кількість балів: 1How many times must the titre of antibodies with paired sera grow to prove the previous result?
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Запитання 16 з 28
16. Запитання
Кількість балів: 1A medicine that prevents virus replication by braking of the DNA synthesis will be effective against:
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Запитання 17 з 28
17. Запитання
Кількість балів: 1What are the most probable clinical signs of RS-infection in children of a school age?
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Запитання 18 з 28
18. Запитання
Кількість балів: 1What treatment is etiologic in case of adenoviral infection?
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Запитання 19 з 28
19. Запитання
Кількість балів: 1What viruses does the RS-virus belong to?
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Запитання 20 з 28
20. Запитання
Кількість балів: 1Children of what age are mainly predisposed to RS-infection?
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Запитання 21 з 28
21. Запитання
Кількість балів: 1What immunity will be formed in the most of patients after RS-infection?
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Запитання 22 з 28
22. Запитання
Кількість балів: 1Where are maximal pathological changes in case of RS-infection localized?
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Запитання 23 з 28
23. Запитання
Кількість балів: 1What is the incubation period of RS-infection?
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Запитання 24 з 28
24. Запитання
Кількість балів: 1Which diagnostic criterion is the most characteristic for adenoviral infection?
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Запитання 25 з 28
25. Запитання
Кількість балів: 1What is the incubation period of adenoviral infection?
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Запитання 26 з 28
26. Запитання
Кількість балів: 1What is the mechanism of adenoviral infection transmission?
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Запитання 27 з 28
27. Запитання
Кількість балів: 1What test is mainly used for express diagnosis of parainfluenza?
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Запитання 28 з 28
28. Запитання
Кількість балів: 1What is the course of latent period in parainfluenza?
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Запитання 1 з 35
1. Запитання
Кількість балів: 1Megakaryocytes are minimally immunoresponsive; such cells are also known as:
Правильно
The primary constituent cells of the immune system are bone-marrow-derived lymphocytes (B cells) and thymus-derived lymphocytes (T cells). Cytokines are polypeptides that modulate the function of immunoresponsive cells, and interleukins are cytokines that are produced by mononuclear cells. Platelets appear not to be immunoresponsive and are involved in blood clotting.
Неправильно
The primary constituent cells of the immune system are bone-marrow-derived lymphocytes (B cells) and thymus-derived lymphocytes (T cells). Cytokines are polypeptides that modulate the function of immunoresponsive cells, and interleukins are cytokines that are produced by mononuclear cells. Platelets appear not to be immunoresponsive and are involved in blood clotting.
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Запитання 2 з 35
2. Запитання
Кількість балів: 1One of the most remarkable aspects of the human immune system is its diversity, that is, the ability to recognize a wide range of antigens and to mount a specific antibody response. This is called clonal selection. At the cellular level, which of the following are primarily responsible for such specificity?
Правильно
The great heterogeneity in the B cell response is characterized by a wide variety of antigenic stimuli. The end result of this remarkable process is a set of very specific surface receptors on B lymphocytes. However, it is the hypervariable regions in the variable domain of these B cells that provide the amino acid residues that confer specificity by synthesis of surface immunoglobulin receptors. T cells, on the other hand, do not secrete immunoglobulins.
Неправильно
The great heterogeneity in the B cell response is characterized by a wide variety of antigenic stimuli. The end result of this remarkable process is a set of very specific surface receptors on B lymphocytes. However, it is the hypervariable regions in the variable domain of these B cells that provide the amino acid residues that confer specificity by synthesis of surface immunoglobulin receptors. T cells, on the other hand, do not secrete immunoglobulins.
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Запитання 3 з 35
3. Запитання
Кількість балів: 1A young girl has had repeated infections with Candida albicans and respiratory viruses since the time she was 3 months old. As part of the clinical evaluation of her immune status, her responses to routine immunization procedures should be tested. In this evaluation, the use of which of the following vaccines is contraindicated?
Правильно
Recurrent severe infection is an indication for clinical evaluation of immune status. Live vaccines, including BCG attenuated from Mycobacterium tuberculosis, should not be used in the evaluation of a patient’s immune competence because patients with severe immunodeficiencies may develop an overwhelming infection from the vaccine. For the same reason, oral (Sabin) polio vaccine is not advisable for use in such persons.
Неправильно
Recurrent severe infection is an indication for clinical evaluation of immune status. Live vaccines, including BCG attenuated from Mycobacterium tuberculosis, should not be used in the evaluation of a patient’s immune competence because patients with severe immunodeficiencies may develop an overwhelming infection from the vaccine. For the same reason, oral (Sabin) polio vaccine is not advisable for use in such persons.
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Запитання 4 з 35
4. Запитання
Кількість балів: 1A 19-year-old college student develops a rash. She works part-time in a pediatric AIDS clinic. Her blood is drawn and tested for specific antibody to the chickenpox virus (varicella-zoster). Which of the following antibody classes would you expect to find if she is immune to chickenpox?
Правильно
The initial response to a new infection is with an IgM class antibody. IgM develops quickly and usually disappears within a few months. The secondary response is IgG and reflects the patient’s immune status or, in the case of chickenpox, a vaccination given.
Неправильно
The initial response to a new infection is with an IgM class antibody. IgM develops quickly and usually disappears within a few months. The secondary response is IgG and reflects the patient’s immune status or, in the case of chickenpox, a vaccination given.
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Запитання 5 з 35
5. Запитання
Кількість балів: 1A 34-year-old male patient visits a physician with complaints of fatigue, weight loss, night sweats, and “swollen glands.” The physician also observes that he has an oral yeast infection. Which of the following tests would most likely reveal the cause of his problems?
Правильно
A male patient with the presentation as outlined in question (fatigue, weight loss, and lymphadenopathy) must be tested for antibodies to HIV. While other antibody tests may be relevant after the primary diagnosis, they must be considered after HIV is ruled out. Certainly, infectious mononucleosis is a possibility, but its occurrence in this age group is not as frequent as HIV. Patients are tested first by an ELISA screening test.
Неправильно
A male patient with the presentation as outlined in question (fatigue, weight loss, and lymphadenopathy) must be tested for antibodies to HIV. While other antibody tests may be relevant after the primary diagnosis, they must be considered after HIV is ruled out. Certainly, infectious mononucleosis is a possibility, but its occurrence in this age group is not as frequent as HIV. Patients are tested first by an ELISA screening test.
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Запитання 6 з 35
6. Запитання
Кількість балів: 1Patients with C5 through C9 complement deficiencies would be most likely to have which of the following infections?
Правильно
Patients with complement deficiencies such as C5 through C9, which form the membrane attack complex (MAC), are predisposed to disseminated meningococcal disease. These patients may also be susceptible to gonococcal infection. There appears to be no disposition to AIDS or to fungal, parasitic, or pneumococcal infections.
Неправильно
Patients with complement deficiencies such as C5 through C9, which form the membrane attack complex (MAC), are predisposed to disseminated meningococcal disease. These patients may also be susceptible to gonococcal infection. There appears to be no disposition to AIDS or to fungal, parasitic, or pneumococcal infections.
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Запитання 7 з 35
7. Запитання
Кількість балів: 1There are at least 10 properties of cytokines. Which of the following is one of these characteristics?
Правильно
There are at least 10 functions of the known cytokines, including mitogenesis, lymphocyte activation, pyrogenesis, lymphocyte proliferation, and T-cell differentiation. Not all cytokines (such as interleukins) are responsible for all of these functions. Cytokines do not activate LPS, but LPS may activate macrophages.
Неправильно
There are at least 10 functions of the known cytokines, including mitogenesis, lymphocyte activation, pyrogenesis, lymphocyte proliferation, and T-cell differentiation. Not all cytokines (such as interleukins) are responsible for all of these functions. Cytokines do not activate LPS, but LPS may activate macrophages.
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Запитання 8 з 35
8. Запитання
Кількість балів: 1Immunity may be natural or acquired. Which of the following best describes acquired immunity?
Правильно
Natural immunity is nonspecific. The description of natural immune functions described are not specific for a certain antigen. For example, certain proteins such as C-reactive protein (CRP) are acute-phase reactants. While elevated CRP is seen in infection, it is not disease-specific. Maternal transfer of antibody, however, is passive but still confers specific immunity. It is termed acquired immunity.
Неправильно
Natural immunity is nonspecific. The description of natural immune functions described are not specific for a certain antigen. For example, certain proteins such as C-reactive protein (CRP) are acute-phase reactants. While elevated CRP is seen in infection, it is not disease-specific. Maternal transfer of antibody, however, is passive but still confers specific immunity. It is termed acquired immunity.
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Запитання 9 з 35
9. Запитання
Кількість балів: 1The major role of T cells in the immune response includes which one of the following?
Правильно
T-cells do not synthesize antibody; that is the task of B cells. Recognition of certain epitopes, lymphokine production, and eradication of “foreign cells” are all functions of T cells. One of the best-recognized T cells is the CD4 cell. The importance of CD4 cells to the immune response is demonstrated by the effects of a specific inhibition of CD4 functions, that is, human immunodeficiency virus (HIV)
Неправильно
T-cells do not synthesize antibody; that is the task of B cells. Recognition of certain epitopes, lymphokine production, and eradication of “foreign cells” are all functions of T cells. One of the best-recognized T cells is the CD4 cell. The importance of CD4 cells to the immune response is demonstrated by the effects of a specific inhibition of CD4 functions, that is, human immunodeficiency virus (HIV)
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Запитання 10 з 35
10. Запитання
Кількість балів: 1Specific immunological unresponsiveness is called tolerance. Which one of the following statements best describes immunological tolerance?
Правильно
Whether an antigen will induce tolerance rather than an immunologic response is largely determined by immunologic maturity of the host, structure, dose of antigen, and administration of immunosuppressive drugs. Tolerance is best maintained by the presence of low concentrations of antigen. T cells become tolerant more readily than B cells
Неправильно
Whether an antigen will induce tolerance rather than an immunologic response is largely determined by immunologic maturity of the host, structure, dose of antigen, and administration of immunosuppressive drugs. Tolerance is best maintained by the presence of low concentrations of antigen. T cells become tolerant more readily than B cells
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Запитання 11 з 35
11. Запитання
Кількість балів: 1It appears that HIV binds selectively to CD4 glycoproteins. Thus, HIV shows a selective infection with the destruction of helper T cells. Which of the following cells exhibit CD4 glycoprotein on their cell surface?
Правильно
Except squamous epithelial cells, all of the cells listed exhibit CD4 glycoprotein on their cell surface, although at lower levels, than do helper T cells. This explains, in part, how HIV infection may be neurotropic. Because of the low levels of CD4 glycoprotein, these cells, as well as colon epithelial cells, are susceptible to HIV infection. Suppressor lymphocytes have a CD8 glycoprotein determinant.
Неправильно
Except squamous epithelial cells, all of the cells listed exhibit CD4 glycoprotein on their cell surface, although at lower levels, than do helper T cells. This explains, in part, how HIV infection may be neurotropic. Because of the low levels of CD4 glycoprotein, these cells, as well as colon epithelial cells, are susceptible to HIV infection. Suppressor lymphocytes have a CD8 glycoprotein determinant.
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Запитання 12 з 35
12. Запитання
Кількість балів: 1Interleukin 1 (IL-1) is a potent cytokine. It is best described by which one of the following statements?
Правильно
Interleukin 1 (IL-1) is produced by a variety of cells. Primarily, it is produced by activated macrophages or monocytes, although it can also be produced by activated B cells, keratinocytes, skin-layer hairy cells, and natural killer cells. IL-1 acts synergistically with IL-6 to stimulate production of IL-2. Human IL-1 consists of α and β forms, or two different proteins. They have limited similarity of amino acid sequence, and the β form is more abundant as a serum protein.
Неправильно
Interleukin 1 (IL-1) is produced by a variety of cells. Primarily, it is produced by activated macrophages or monocytes, although it can also be produced by activated B cells, keratinocytes, skin-layer hairy cells, and natural killer cells. IL-1 acts synergistically with IL-6 to stimulate production of IL-2. Human IL-1 consists of α and β forms, or two different proteins. They have limited similarity of amino acid sequence, and the β form is more abundant as a serum protein.
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Запитання 13 з 35
13. Запитання
Кількість балів: 1IgA antibody is the first line of defense against infections at the mucous membrane. It is usually an early specific antibody. Which of the following statements regarding IgA is not true?
Правильно
Each secretory IgA molecule has a molecular weight of 400,000 and consists of two H2L2 units and one molecule each of J chain and secretory component. Some IgA exists in serum as a monomer H2L2 with a molecular weight of 160,000. Some bacteria, such as Neisseria, can destroy IgA1 by producing protease. It is the major immunoglobulin in milk, saliva, tears, and colostrum. IgA does not fix complement, so one would anticipate that a complement fixation test would not be useful for IgA antibody.
Неправильно
Each secretory IgA molecule has a molecular weight of 400,000 and consists of two H2L2 units and one molecule each of J chain and secretory component. Some IgA exists in serum as a monomer H2L2 with a molecular weight of 160,000. Some bacteria, such as Neisseria, can destroy IgA1 by producing protease. It is the major immunoglobulin in milk, saliva, tears, and colostrum. IgA does not fix complement, so one would anticipate that a complement fixation test would not be useful for IgA antibody.
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Запитання 14 з 35
14. Запитання
Кількість балів: 1Complement is a series of important host proteins which provide protection from invasion by foreign microorganisms. Which one of the following statements best describes complement?
Правильно
Both IgG and IgM activate complement by the classic pathway, while IgA activates it by the alternative pathway. Neither IgD nor IgE can activate complement. Complement is a system of several proteins that is activated by either an immune or a nonimmune pathway. Both of these pathways result in the production of many biologically active components that cause cell lysis and death.
Неправильно
Both IgG and IgM activate complement by the classic pathway, while IgA activates it by the alternative pathway. Neither IgD nor IgE can activate complement. Complement is a system of several proteins that is activated by either an immune or a nonimmune pathway. Both of these pathways result in the production of many biologically active components that cause cell lysis and death.
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Запитання 15 з 35
15. Запитання
Кількість балів: 1Which immunoglobulin has no known function, but is present on the surface of B lymphocytes? It may function as an antigen receptor.
Правильно
IgD antibody consists of two light chains and two heavy chains. Its role is not known but can be found on the surface of lymphocytes where it may act as a surface receptor.
Неправильно
IgD antibody consists of two light chains and two heavy chains. Its role is not known but can be found on the surface of lymphocytes where it may act as a surface receptor.
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Запитання 16 з 35
16. Запитання
Кількість балів: 1Which immunoglobulin is the primary antibody in saliva, tears, and intestinal and genital secretions?
Правильно
IgA antibody is involved in local immunity at the level of the mucous membrane. IgA antibody also arises early in disease. IgA antibody is shortlived and will disappear similarly to IgM.
Неправильно
IgA antibody is involved in local immunity at the level of the mucous membrane. IgA antibody also arises early in disease. IgA antibody is shortlived and will disappear similarly to IgM.
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Запитання 17 з 35
17. Запитання
Кількість балів: 1Which immunoglobulin is the predominant antibody in the secondary immune response? It has four subclasses.
Правильно
IgG antibody persists in most people and indicates the antigens to which they have been exposed. IgG is not formed early in infection but is a secondary response arising weeks to months after antigenic challenge. IgG also has a built-in memory. Even people with very low levels of specific IgG will respond to an antigen challenge with an IgG response
Неправильно
IgG antibody persists in most people and indicates the antigens to which they have been exposed. IgG is not formed early in infection but is a secondary response arising weeks to months after antigenic challenge. IgG also has a built-in memory. Even people with very low levels of specific IgG will respond to an antigen challenge with an IgG response
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Запитання 18 з 35
18. Запитання
Кількість балів: 1IgM antibody (1:200) to Borrelia burgdorferi is associated with:
Правильно
Borrelia burgdorferi, the causative agent of Lyme disease, elicits an acute antibody response. IgM appears within days to a few weeks following tick bite, and IgG appears a few weeks later. IgG persists, IgM does not.
Неправильно
Borrelia burgdorferi, the causative agent of Lyme disease, elicits an acute antibody response. IgM appears within days to a few weeks following tick bite, and IgG appears a few weeks later. IgG persists, IgM does not.
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Запитання 19 з 35
19. Запитання
Кількість балів: 1Elevated IgG and IgM antibody titers to parvovirus suggest a diagnosis of
Правильно
Fifth disease is a viral exanthem commonly seen in children 8 to 12 years old. Children are ill for a few days but recover without incident. Unfortunately, if a pregnant female acquires the disease in the first trimester of pregnancy, the fetus is at risk. The causative agent is thought to be a parvovirus (parvovirus B19).
Неправильно
Fifth disease is a viral exanthem commonly seen in children 8 to 12 years old. Children are ill for a few days but recover without incident. Unfortunately, if a pregnant female acquires the disease in the first trimester of pregnancy, the fetus is at risk. The causative agent is thought to be a parvovirus (parvovirus B19).
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Запитання 20 з 35
20. Запитання
Кількість балів: 1A patient has an increased antibody titer to delta agent. You would most likely suspect
Fifth disease:Правильно
Delta agent is a recently discovered antigen associated with HBsAg. Its presence usually correlates with HBsAg chronic carriers who have chronic 248 Microbiology 8279_Tilton_07.f.qxd 11/14/01 5:03 PM Page 248 active hepatitis. EIA and radioimmunoassay (RIA) tests are available to detect antibodies to delta agent.
Неправильно
Delta agent is a recently discovered antigen associated with HBsAg. Its presence usually correlates with HBsAg chronic carriers who have chronic 248 Microbiology 8279_Tilton_07.f.qxd 11/14/01 5:03 PM Page 248 active hepatitis. EIA and radioimmunoassay (RIA) tests are available to detect antibodies to delta agent.
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Запитання 21 з 35
21. Запитання
Кількість балів: 1Ataxia-telangiectasia usually is associated with Humoral Cellular