Q: A virus is described as having a single-stranded, positive-sense RNA genome that can be directly translated by host ribosomes. Which equation best represents the initial step in viral protein synthesis?

$$\text{ssRNA}^+ \xrightarrow{\text{translation}} \text{Viral Proteins}$$

Q: Which of the following equations best represents the process by which a retrovirus generates mRNA for protein synthesis?

$$\text{ssRNA}^+ \xrightarrow{\text{reverse transcription}} \text{dsDNA} \xrightarrow{\text{transcription}} \text{mRNA}$$

Question 1

Which of the following best describes why RNA viruses mutate more rapidly than DNA viruses?

Accepted Answer

RNA polymerases lack proofreading capabilities, leading to higher mutation rates.

Question 2

A virus with a helical capsid, an envelope, and a segmented negative-sense RNA genome is most likely classified in which viral family?

Accepted Answer

Orthomyxoviridae

Question 3

Which step in the animal virus replication cycle is unique to animal viruses and not found in bacteriophage replication?

Accepted Answer

Uncoating

Question 4

A patient is diagnosed with a persistent viral infection that periodically flares up with symptoms, followed by long periods of dormancy. Which virus is most likely responsible?

Accepted Answer

Herpes simplex virus (HSV)

Question 5

Which of the following best explains the process of antigenic shift in influenza viruses?

Accepted Answer

Reassortment of genome segments when two different strains coinfect a host cell

Question 6

Which laboratory method is most appropriate for quantifying the number of infectious bacteriophages in a sample?

Accepted Answer

Plaque assay

Question 7

Which of the following antiviral drugs acts by inhibiting the release of influenza virions from the host cell surface?

Accepted Answer

Oseltamivir

Question 8

A virus is described as having a single-stranded, positive-sense RNA genome that can be directly translated by host ribosomes. Which equation best represents the initial step in viral protein synthesis?

Accepted Answer

$$	ext{ssRNA}^+ \xrightarrow{	ext{translation}} 	ext{Viral Proteins}$$

Question 9

Which of the following is a medically important consequence of phage conversion in bacteria?

Accepted Answer

Bacteria may acquire genes encoding toxins, increasing their pathogenicity.

Question 10

Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that lack genetic material and cause spongiform encephalopathies.

Question 11

A virus is described as naked, with an icosahedral capsid and a single-stranded DNA genome. Which family does it most likely belong to?

Accepted Answer

Parvoviridae

Question 12

Which of the following best describes the difference between the lytic and lysogenic cycles of bacteriophage replication?

Accepted Answer

The lytic cycle results in host cell lysis and immediate production of new phages, while the lysogenic cycle involves integration of phage DNA into the host genome and dormancy.

Question 13

Which of the following is a key reason why antiviral drugs are more difficult to develop than antibacterial drugs?

Accepted Answer

Viruses are obligate intracellular pathogens with fewer unique targets for selective toxicity.

Question 14

Which of the following best explains why vaccines are an effective means to limit viral infections?

Accepted Answer

Vaccines train the immune system to recognize and respond to viral antigens before infection occurs.

Question 15

A laboratory test uses purified antibodies attached to latex beads to detect viral antigens in a patient sample. What is this test called?

Accepted Answer

Agglutination test

Question 16

Which of the following viruses is known to be oncogenic and associated with human cancers?

Accepted Answer

Human papillomavirus (HPV)

Question 17

Which of the following best describes the host range of a virus?

Accepted Answer

The collection of species that a virus can infect

Question 18

Which of the following equations best represents the process by which a retrovirus generates mRNA for protein synthesis?

Accepted Answer

$$	ext{ssRNA}^+ \xrightarrow{	ext{reverse transcription}} 	ext{dsDNA} \xrightarrow{	ext{transcription}} 	ext{mRNA}$$

Question 19

Which of the following is a limitation of ELISA and agglutination assays for viral detection?

Accepted Answer

They may not detect viruses that have undergone antigenic shift.

Viruses and Prions: Structure, Classification, Replication, and Clinical Aspects

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