Question 1

Which enzyme is unique to retroviruses and is responsible for synthesizing double-stranded DNA from a single-stranded RNA genome?

Accepted Answer

Reverse transcriptase (RT)

Question 2

HIV can only infect host cells that express which of the following on their surface?

Accepted Answer

CD4 receptor and a coreceptor (such as CCR5 or CXCR4)

Question 3

Which of the following best explains why HIV infection is difficult to cure?

Accepted Answer

HIV genes are permanently integrated into the host DNA.

Question 4

A patient is found to be naturally resistant to HIV infection. Which of the following genetic traits is most likely responsible for this resistance?

Accepted Answer

A nonfunctional CCR5 coreceptor

Question 5

Which of the following is the correct sequence of events in the HIV multiplication cycle after the virus enters a host cell?

Accepted Answer

Reverse transcription → Integration of viral DNA into host genome → Translation of viral proteins

Question 6

Which of the following best describes the main route of HIV transmission in the United States according to recent epidemiological data?

Accepted Answer

Male-to-male sexual contact

Question 7

Why does HIV not survive long outside the human body?

Accepted Answer

It is an enveloped virus and is sensitive to environmental conditions.

Question 8

Which of the following is a function of the HIV integrase enzyme?

Accepted Answer

Integrating viral DNA into the host cell genome

Question 9

A newborn is diagnosed with HIV infection. Which of the following is the most likely route of transmission?

Accepted Answer

Transplacental transfer or breastfeeding

Question 10

Which of the following best explains the role of the GP-120 protein in HIV infection?

Accepted Answer

It is the docking glycoprotein that binds to the CD4 receptor on host cells.

Question 11

A patient with HIV is being treated with a reverse transcriptase inhibitor. Which step in the viral life cycle is directly affected by this drug?

Accepted Answer

Synthesis of double-stranded DNA from viral RNA

Question 12

Which of the following equations best represents the process catalyzed by reverse transcriptase in HIV?

Accepted Answer

$RNA \rightarrow DNA$

Question 13

If a mutation occurred in the HIV GP-41 protein, which process would most likely be impaired?

Accepted Answer

Fusion of the viral envelope with the host cell membrane

Question 14

Which of the following statements about antiretroviral therapy (ART) is correct?

Accepted Answer

ART slows the progression of HIV disease by inhibiting viral replication.

Question 15

A patient with HIV has a mutation in the CXCR4 coreceptor. Which of the following is most likely to occur?

Accepted Answer

The patient may be resistant to certain strains of HIV that use CXCR4 for entry.

Question 16

Which of the following best explains why sharing needles increases the risk of HIV transmission?

Accepted Answer

Blood-to-blood contact allows direct transfer of the virus.

Question 17

Which of the following is NOT a common route of HIV transmission?

Accepted Answer

Casual contact such as shaking hands

Question 18

Which of the following best describes the epidemiological trend of HIV morbidity after the introduction of antiretroviral therapy in the 2000s?

Accepted Answer

The progression of HIV disease was slowed.

Question 19

Which of the following is a direct consequence of HIV integrating its genome into host DNA?

Accepted Answer

The virus can remain latent and reactivate later.

Question 20

A researcher is studying a new drug that blocks the interaction between GP-120 and the CD4 receptor. Which step in the HIV life cycle would this drug most directly inhibit?

Accepted Answer

Attachment of the virus to the host cell

Chapter 25: RNA Viruses that Infect Humans – Human Retroviruses and HIV

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