Question 1

Which of the following best describes the main difference between the International Committee on Taxonomy of Viruses (ICTV) system and the Baltimore classification system for viruses?

Accepted Answer

The ICTV system uses genetic material and morphology, while the Baltimore system is based on the relationship between the viral genome and messenger RNA.

Question 2

A patient presents with jaundice and is diagnosed with hepatitis B. Which of the following best describes the genome and replication strategy of the hepatitis B virus?

Accepted Answer

Circular partially double-stranded DNA that replicates via an RNA intermediate using reverse transcriptase.

Question 3

Which of the following statements about the structure of viruses is correct?

Accepted Answer

The capsid is composed of subunits called protomeres, which assemble into capsomeres.

Question 4

A laboratory is studying a virus with a helical capsid, an envelope, and a negative-sense single-stranded RNA genome. Which of the following viruses best fits this description?

Accepted Answer

Influenza virus

Question 5

During the lytic cycle of a bacteriophage, which of the following best describes the eclipse period?

Accepted Answer

The phase when no infectious phage particles are detectable inside the host cell as viral components are being synthesized.

Question 6

Which of the following is a key reason why RNA viruses, such as coronaviruses, evolve more rapidly than DNA viruses?

Accepted Answer

RNA-dependent RNA polymerases lack proofreading activity, resulting in higher mutation rates.

Question 7

A virus is found to have a nonenveloped icosahedral capsid and a single-stranded positive-sense RNA genome. Which family does this virus most likely belong to?

Accepted Answer

Picornaviridae

Question 8

Which of the following best explains why enveloped viruses are generally more sensitive to alcohol-based disinfectants than nonenveloped viruses?

Accepted Answer

Alcohol disrupts the lipid bilayer of the envelope, which is essential for infectivity.

Question 9

A patient is diagnosed with rabies after being bitten by a wild animal. Which of the following statements about the rabies virus is correct?

Accepted Answer

It is an enveloped virus with a bullet-shaped morphology and a negative-sense single-stranded RNA genome.

Question 10

Which of the following best distinguishes viroids from virusoids?

Accepted Answer

Viroids do not encode proteins and replicate independently, while virusoids require a helper virus for replication.

Question 11

A researcher is developing a gene therapy vector using a virus that integrates its genome into the host DNA via reverse transcription. Which viral family is most appropriate for this purpose?

Accepted Answer

Retroviridae

Question 12

Which of the following is a cytopathic effect commonly associated with herpes simplex virus infection?

Accepted Answer

Cell fusion leading to multinucleated giant cells

Question 13

A patient with a history of unprotected sexual contact develops genital warts. Which virus is most likely responsible, and what is a potential long-term complication?

Accepted Answer

Human papillomavirus (HPV); cervical cancer

Question 14

Which of the following best describes the process of uncoating in animal virus replication?

Accepted Answer

The viral nucleic acid is released from the capsid after entry into the host cell, often involving host enzymes.

Question 15

A new antiviral drug is found to inhibit the activity of viral reverse transcriptase. Which group of viruses would be most affected by this drug?

Accepted Answer

Group VI: Reverse-transcribing single-stranded RNA viruses

Question 16

Which of the following best explains why the segmented genome of influenza A virus contributes to the emergence of new pandemic strains?

Accepted Answer

Segmented genomes enable reassortment of gene segments when two different strains infect the same cell.

Question 17

A patient is diagnosed with Creutzfeldt-Jakob disease. Which of the following statements about the causative agent is correct?

Accepted Answer

It is a prion, an infectious protein lacking nucleic acid.

Question 18

Which of the following best describes the host range of bacteriophages used in therapeutic phage therapy?

Accepted Answer

Bacteriophages are usually specific for one species or even a particular strain of bacteria.

Question 19

Which of the following is a correct sequence of events in the multiplication of a naked animal virus?

Accepted Answer

Adsorption, penetration, uncoating, replication, assembly, release

Question 20

Which of the following best describes the difference between abortive and lytic viral infections in animal cells?

Accepted Answer

Abortive infections occur in nonpermissive cells with no viral production, while lytic infections result in host cell death and release of new virions.

Viruses, Viroids, and Prions: Structure, Classification, and Pathogenicity

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