Question 1

Which of the following best describes the genome of SARS-CoV-2 and its immediate fate upon entry into the host cell?

Accepted Answer

Positive-sense single-stranded RNA that can be directly translated into proteins.

Question 2

Which enzyme is carried by negative-strand RNA viruses and is essential for their replication in host cells?

Accepted Answer

RNA-dependent RNA polymerase

Question 3

A patient presents with fever, cough, and loss of smell. Laboratory tests confirm infection with SARS-CoV-2. Which host cell receptor is primarily responsible for viral entry?

Accepted Answer

ACE2

Question 4

Which of the following best explains why antigenic shift in influenza viruses can lead to pandemics?

Accepted Answer

It allows for recombination of RNA segments from different species, creating novel viruses.

Question 5

Which of the following is a key difference between the replication of positive-strand RNA viruses and retroviruses?

Accepted Answer

Retroviruses integrate a DNA copy of their genome into the host genome using reverse transcriptase.

Question 6

Which diagnostic technique is most sensitive for detecting an active SARS-CoV-2 infection?

Accepted Answer

Reverse transcriptase quantitative polymerase chain reaction (RT-qPCR)

Question 7

A patient with HIV is found to have a low CD4+ T cell count and Kaposi’s sarcoma. Which stage of HIV infection is this patient most likely experiencing?

Accepted Answer

Chronic symptomatic phase (AIDS)

Question 8

Which of the following best describes the process of antigenic drift in influenza viruses?

Accepted Answer

Gradual accumulation of point mutations in viral genes

Question 9

Which of the following is a common mechanism by which SARS-CoV-2 causes severe disease in the lungs?

Accepted Answer

Induction of a cytokine storm leading to immune-mediated tissue damage

Question 10

Which of the following viruses is transmitted primarily through direct contact with body fluids and is associated with integration of its genome into host DNA?

Accepted Answer

HIV

Question 11

Which of the following best describes the replication strategy of a negative-strand RNA virus?

Accepted Answer

The genome serves as a template for synthesis of positive-strand mRNA by viral RNA-dependent RNA polymerase.

Question 12

Which of the following is a reason why there is no effective vaccine for HIV?

Accepted Answer

HIV has a high mutation rate, leading to antigenic variation.

Question 13

Which of the following is a characteristic of measles virus (MeV)?

Accepted Answer

It is an enveloped, negative-strand RNA virus.

Question 14

Which of the following best explains why SARS-CoV-2 can infect multiple organ systems?

Accepted Answer

ACE2 receptors, which the virus uses for entry, are present in many tissues.

Question 15

Which of the following is the correct order of events for the replication of a retrovirus?

Accepted Answer

$$ssRNA \rightarrow dsDNA \rightarrow mRNA \rightarrow Protein$$

Question 16

Which of the following is a primary reason why neuraminidase inhibitors are effective in treating influenza?

Accepted Answer

They prevent the release of new virions from infected cells.

Question 17

A patient is diagnosed with COVID-19 and develops severe respiratory distress. Which immune response is most likely responsible for the progression to multi-organ failure?

Accepted Answer

Cytokine storm

Question 18

Which of the following best describes the process by which HIV enters a host cell?

Accepted Answer

Binding of gp120 to CD4 and a chemokine co-receptor, followed by membrane fusion

Question 19

Which of the following is a distinguishing feature of the influenza virus genome compared to SARS-CoV-2?

Accepted Answer

Influenza virus has a segmented negative-strand RNA genome, while SARS-CoV-2 has a non-segmented positive-strand RNA genome.

Viral Structure, Replication, and Pathogenesis: Focus on SARS-CoV-2, Influenza, Measles, and HIV

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