Interferons are an important part of the host defense against viral infections. What is interferon’s principal mode of action?
(A) It is present in the serum of healthy individuals, providing a viral surveillance role.
(B) It coats viral particles and blocks their attachment to cells.
(C) It induces synthesis of one or more cellular proteins that inhibit translation or transcription.
(D) It protects the virus-infected cell that produced it from cell death.
A 9-month-old girl is taken to the emergency room because of fever and persistent cough. Rales are heard in her left chest on physical examination. An infiltrate in her left lung is seen on the chest radiograph. Pneumonia is diagnosed. Which of the following is the most likely cause?
(D) Respiratory syncytial virus
Which one of the following is a fundamental principle of viral disease causation?
(A) One virus type induces a single disease syndrome.
(B) Many viral infections are subclinical and do not produce clinical disease.
(C) The type of disease produced by a virus can be predicted by the morphology of that virus.
(D) A particular disease syndrome has a single viral cause.
The skin is a formidable barrier to virus entry, but a few viruses are able to breach this barrier and initiate infection of the host. Which of the following is an example of a virus that enters through skin abrasions?
A 40-year-old man has HIV/AIDS characterized by a low CD4 count and a high viral load. Highly active antiretroviral therapy (HAART) will be initiated. One of the drugs under consideration is a nucleoside analog that inhibits viral reverse transcriptase and is active against both HIV and hepatitis B virus. That drug is
A 40-year-old man has HIV/AIDS characterized by a low CD4 count and a high viral load. Highly active antiretroviral therapy (HAART) will be initiated. One of the drugs under consideration is a nucleoside analog that inhibits viral reverse transcriptase and is active against both HIV and hepatitis B virus.
A peptidomimetic agent that blocks virus-mediated cleavage of viral structural protein precursors is chosen as a second drug. That drug is
A 63-year-old woman is hospitalized for treatment of leukemia. One day after admission she develops chills, fever, cough, headache, and myalgia. She states that her husband had a similar illness a few days earlier. There is major concern about a respiratory virus outbreak in the staff of the chemotherapy ward and in the patients on that ward. A synthetic amine that inhibits influenza A virus by blocking viral uncoating is chosen for prophylactic treatment of the staff and patients. That drug is
Which one of the following statements describes an advantage of killed-virus vaccines over attenuated live-virus vaccines?
(A) Killed-virus vaccines induce a broader range of immune responses than do attenuated live-virus vaccines.
(B) Killed-virus vaccines more closely mimic natural infections than do attenuated live-virus vaccines.
(C) Killed-virus vaccines pose no risk that vaccine virus might be transmitted to susceptible contacts.
(D) Killed-virus vaccines are efficacious against respiratory virus infections because they induce good mucosal immunity.
What type of hepatitis B vaccine is currently in use in the United States?
(A) Synthetic peptide vaccine
(C) Attenuated live-virus vaccine
(D) Subunit vaccine produced using recombinant DNA
Which one of the following phrases accurately describes viral neutralizing antibodies?
(A) Directed against viral protein determinants on the outside of the virus particle
(B) Appear in the host sooner after viral infection than interferon
(C) Directed against viral nucleic acid sequences
(D) Induced only by disease-causing viruses
(E) Of little importance to immunity to viral infection
Many viruses use the respiratory tract as the route of entry to initiate infections. Which of the following virus groups does not?
Which of the following licensed virus vaccines is a subunit vaccine prepared using recombinant DNA technology?
Which of the following viruses is the most common cause of neonatal infections in the United States?
(F) Human immunodeficiency virus
Which one of the following statements concerning interferons is least accurate?
(A) Interferons are proteins that influence host defenses in many ways, one of which is the induction of an antiviral state.
(B) Interferons are synthesized only by virus-infected cells.
(C) Interferons inhibit a broad range of viruses, not just the virus that induced the interferon.
(D) Interferons induce the synthesis of a ribonuclease that degrades viral mRNA.
Each of the following statements concerning viral vaccines is correct except
(A) In live attenuated vaccines, the virus has lost its ability to cause disease but has retained its ability to induce neutralizing antibody.
(B) In live attenuated vaccines, the possibility of reversion to virulence is of concern.
(C) With inactivated vaccines, IgA mucosal immunity is usually induced.
(D) With inactivated vaccines, protective immunity is mainly caused by the production of IgG.