Question 1

Which of the following best explains why the influenza vaccine must be administered annually?

Accepted Answer

The influenza virus undergoes antigenic drift, causing small mutations in HA and NA proteins, which reduces the effectiveness of previous antibodies.

Question 2

Which viral protein is responsible for mediating the entry of the influenza virus into host cells?

Accepted Answer

Hemagglutinin (HA)

Question 3

A patient presents with a severe respiratory infection. Laboratory tests reveal an enveloped, +ssRNA virus with a spike protein that binds to ACE2 receptors. Which virus is most likely responsible?

Accepted Answer

SARS-CoV-2

Question 4

Which of the following best describes the mechanism of action of acyclovir in treating HSV infections?

Accepted Answer

Acyclovir is activated in HSV-infected cells and inhibits viral DNA polymerase, causing DNA chain termination.

Question 5

Which of the following is a key reason why HIV infection cannot be cured by antiretroviral therapy (ART)?

Accepted Answer

HIV persists as a latent provirus integrated into the host DNA of long-lived CD4+ T cells.

Question 6

Which of the following best describes the pathogenesis of measles virus?

Accepted Answer

Measles infects immune cells, causes viremia, and destroys immune memory cells, leading to immune amnesia.

Question 7

Which of the following statements about antigenic shift in influenza viruses is correct?

Accepted Answer

Antigenic shift involves reassortment of genome segments, leading to new viral strains and potential pandemics.

Question 8

A patient develops shingles years after recovering from chickenpox. Which viral property explains this phenomenon?

Accepted Answer

The virus establishes latency in sensory neurons and can reactivate later in life.

Question 9

Which of the following best explains how high-risk HPV types contribute to oncogenesis?

Accepted Answer

HPV E6 and E7 proteins inactivate p53 and Rb tumor suppressors, promoting uncontrolled cell division.

Question 10

Which of the following is a major reason why norovirus outbreaks are difficult to control in community settings?

Accepted Answer

Norovirus has a very low infectious dose and is highly environmentally stable.

Question 11

Which of the following antiviral drug classes targets the release of new influenza virions from infected cells?

Accepted Answer

Neuraminidase inhibitors

Question 12

A patient with HIV is started on ART and achieves an undetectable viral load. Why must ART be continued for life?

Accepted Answer

Latent HIV persists in CD4+ T-cell reservoirs and can reactivate if therapy is stopped.

Question 13

Which of the following best describes the effect of measles-induced 'immune amnesia'?

Accepted Answer

Destruction of immune memory cells, leading to loss of preexisting immunity to other pathogens.

Question 14

Which of the following is a common feature of both influenza and SARS-CoV-2?

Accepted Answer

Both infect respiratory epithelial cells and are transmitted by droplets and aerosols.

Question 15

Which of the following best explains why selective toxicity is more difficult to achieve with antiviral drugs compared to antibacterial drugs?

Accepted Answer

Viruses use host cell machinery for replication, making it harder to target the virus without harming host cells.

Question 16

Which of the following is the primary target cell for HIV infection?

Accepted Answer

CD4+ T cells

Question 17

Which of the following best describes the mechanism by which norovirus causes diarrhea?

Accepted Answer

Norovirus disrupts ion transport and blunts villi in enterocytes, leading to decreased absorption and increased fluid secretion.

Question 18

Which of the following is a key feature of herpes simplex virus (HSV) latency?

Accepted Answer

Viral DNA persists in sensory neurons with minimal gene expression and no virion production.

Question 19

Which of the following best explains why stress or immune suppression can trigger reactivation of latent HSV?

Accepted Answer

Stress or immune suppression disrupts latency, allowing lytic viral genes to be expressed and the virus to reactivate.

DNA & RNA Viral Pathogens: Diseases by Body System

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