Virus Quiz : Test your knowledge

1. Which of the following statements about viral capsids is/are correct?

1. They protect the viral nucleic acid from environmental damage.
2. They may determine the symmetry (helical or icosahedral) of the virus.
3. They are composed primarily of nucleic acids.

Select the correct answer using the code below:

1. 1 only
2. 1 and 2 only
3. 1 and 3 only
4. 1, 2 and 3

2. “Positive-sense” RNA viruses are those whose RNA genome:

1. Must first be transcribed into DNA before any proteins are made.
2. Can directly function as mRNA for protein synthesis.
3. Is always segmented.
4. Cannot be translated by host ribosomes.

3. Which of the following best describes a “defective interfering particle” in virology?

1. A viral particle that lacks essential genetic material and can interfere with replication of standard virus.
2. A fully functional virus that interferes with the host immune response.
3. A virus that only infects arthropods and not vertebrates.
4. A virus that has no capsid but replicates normally.

4. Consider the following statements about viral haemagglutinin (as in influenza):

1. It is a viral surface glycoprotein involved in attachment to host cells.
2. It binds to sialic acid residues on host cell membranes.
3. It is responsible for enzymatic cleavage of neuraminic acid from host surfaces.

Which of the statements given above is/are correct?

1. 1 only
2. 1 and 2 only
3. 2 and 3 only
4. 1, 2 and 3

5. In the context of viral infections, “quasispecies” refers to:

1. A group of identical viral clones that never mutate.
2. A dynamic population of closely related viral variants within a host.
3. A virus that infects multiple species without any mutation.
4. A virus that cannot adapt to selective pressures.

6. Which of the following is the most appropriate explanation for “viral latency”?

1. Continuous high-level production of virions without symptoms.
2. Presence of viral genome in host cells with minimal or no productive replication, punctuated by episodes of reactivation.
3. Complete elimination of viral genome from the host.
4. Inability of the virus to enter host cells.

7. With reference to “viremia”, which of the following statements is/are correct?

1. It denotes the presence of viruses in the bloodstream.
2. It may be cell-free or cell-associated.
3. It always indicates severe clinical disease.

Select the correct answer using the code below:

1. 1 and 2 only
2. 1 and 3 only
3. 2 and 3 only
4. 1, 2 and 3

8. Which of the following laboratory findings best supports the diagnosis of an acute viral infection rather than past infection?

1. Presence of IgM antibodies specific to the virus.
2. Presence of only IgG antibodies in high titre, no IgM.
3. Presence of memory T cells reactive to viral antigens.
4. Absence of any viral markers.

9. With reference to antiviral drugs, which of the following mechanisms is correctly matched with its target?

1. Neuraminidase inhibitors – Block release of influenza virions from infected cells.
2. Reverse transcriptase inhibitors – Inhibit DNA polymerase of bacteria.
3. Protease inhibitors – Prevent host digestive enzyme secretion.
4. Fusion inhibitors – Enhance viral entry into host cells.

10. In an epidemic of a novel respiratory virus, which of the following factors will most directly determine the “case fatality rate” (CFR)?

1. Number of deaths due to the virus divided by total population at risk.
2. Number of deaths due to the virus divided by number of confirmed cases of the disease.
3. Number of deaths in a year from all causes divided by total confirmed viral cases.
4. Number of confirmed cases divided by number of deaths from all causes.