Question 1

Which of the following statements best explains why viruses are considered obligate intracellular pathogens?

Accepted Answer

They require host cell energy and machinery to replicate their genome and produce new virions.

Question 2

A scientist isolates a virus with a helical capsid, an RNA genome, and a lipid envelope. Which of the following viruses is most likely to share these features?

Accepted Answer

Ebola virus

Question 3

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

Accepted Answer

A major genetic reassortment when two different strains coinfect a host cell, leading to a new viral strain.

Question 4

Which of the following is a plausible reason why RNA viruses mutate more rapidly than DNA viruses?

Accepted Answer

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

Question 5

A patient is diagnosed with a persistent viral infection that periodically flares up and then becomes dormant. Which virus is most likely responsible for this pattern?

Accepted Answer

Herpes simplex virus-1 (HSV-1)

Question 6

Which of the following best describes the function of viral spikes (peplomers)?

Accepted Answer

They help viruses attach to and gain entry into specific host cells.

Question 7

A laboratory is using a plaque assay to quantify bacteriophages. What does each plaque on the bacterial lawn represent?

Accepted Answer

A single bacteriophage in the initial sample

Question 8

Which of the following antiviral drugs works by mimicking normal nucleotides and causing premature termination of viral nucleic acid synthesis?

Accepted Answer

Acyclovir

Question 9

A virus is found to have a segmented RNA genome and undergoes frequent reassortment. Which process is most likely to result in the emergence of a pandemic strain?

Accepted Answer

Antigenic shift

Question 10

Which of the following is a distinguishing feature of prions compared to viruses?

Accepted Answer

Prions are infectious proteins with no genetic material.

Question 11

A patient receives a blood transfusion in 1976 and later develops liver cancer. Years later, a new virus is discovered in her archived blood sample. Which of the following methods would be most sensitive and specific for detecting the viral genome in her sample?

Accepted Answer

Polymerase chain reaction (PCR)

Question 12

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.

Question 13

Which of the following viruses is classified as oncogenic and is associated with cervical cancer?

Accepted Answer

Human papillomavirus (HPV)

Question 14

A virus is described as having a broad tropism. What does this mean?

Accepted Answer

It can infect a wide range of cell types or tissues within a host.

Question 15

Which of the following is NOT a property used to classify viruses?

Accepted Answer

Ability to metabolize glucose

Question 16

Which of the following best describes the mechanism by which prions cause disease?

Accepted Answer

They induce misfolding of normal proteins, leading to brain tissue degeneration.

Question 17

A new virus is found to have genes similar to hepatitis C virus. Animals vaccinated against hepatitis C show a strong immune reaction to the new virus in a latex agglutination test. What does this suggest?

Accepted Answer

The new virus shares antigenic determinants with hepatitis C virus.

Question 18

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

Accepted Answer

They require well-characterized antigens and may not detect viruses that have undergone antigenic shift.

Question 19

Which of the following best explains why antiviral drugs are difficult to design?

Accepted Answer

Viruses are obligate intracellular pathogens with few chemically distinct targets.

Question 20

A patient is infected with a retrovirus. Which class of antiviral drug would most likely be prescribed to inhibit viral replication?

Accepted Answer

Nucleoside reverse transcriptase inhibitors (NRTIs)

Viruses and Prions: Structure, Replication, and Clinical Relevance

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