Question 1

What protein protects viral RNA from degradation by host cell cytoplasmic enzymes?&#10;A) gp120&#10;B) RNase&#10;C) Vif protein&#10;D) Rev protein

Accepted Answer

Vif protein is protective of viral RNA in the host cytoplasm. RNase is an enzyme that destroys RNA. The surface protein gp120 is structural and is involved in viral attachment to host cells. Rev protein promotes RNA stabilization in the nucleus in preparation for export into the cytoplasm.

Question 2

Which of the following agents is/are entry/fusion inhibitor(s) administered to treat HIV infection?
I. Maraviroc
II. Enfuvirtide
III. Zidovudine

A) I only
B) III only
C) I and II
D) II and III
E) I, II, and III

I and II

Accepted Answer

Maraviroc prevents binding of the HIV virus to host CCR5, which prevents viral attachment to host cells. Enfuvirtide is a fusion inhibitor that prevents attached viruses from fusing with the host cell membrane, which prevents the virus from entering and infecting the host cell. Zidovudine is a reverse transcriptase inhibitor and does not block attachment or fusion.

Question 3

What is the mechanism of HIV-induced death of follicular dendritic cells (FDCs)?&#10;A) TNF released by CD8 cells&#10;B) Lysis following virus production&#10;C) Fas expression upregulated on FDCs&#10;D) Perforin/granzyme-induced apoptosis

Accepted Answer

Following infection with HIV, which is initially concentrated in the germinal centers of the lymph nodes, infected FDCs upregulate Fas and are killed by CD8 T cells expressing FasL.

Question 4

Proteins from _______________ genes combine with RNase to form the viral reverse transcriptase complex?&#10;A) Tat and rev&#10;B) Pol and vpr&#10;C) Vpu and nef&#10;D) Gag and env

Accepted Answer

Pol gene products complex with RNase and vpr gene products to form the reverse transcriptase complex prior to transcription of DNA from viral RNA.

Question 5

During the initial infection with HIV, the virus is concentrated in the:&#10;A) Thymus&#10;B) Bone marrow&#10;C) Lymph nodes&#10;D) Site of exposure

Accepted Answer

During the initial stages of HIV infection, the virus is concentrated in the germinal centers of the lymph nodes, where follicular dendritic cells (FDCs) capture virus using iccosomes. The FDCs eventually succumb to the infection and are killed by Fas:FasL interactions with CD8 T cells.

Question 6

After the human immunodeficiency virus (HIV) binds to CD4 on a T cell, what other molecule does it need to bind for entry into the host cell?&#10;A) H-1&#10;B) H-2&#10;C) CCR5&#10;D) CXCR4

Accepted Answer

CXCR4 is a chemokine receptor found on the surface of CD4 T cells, among others. HIV must bind to both CD4 and CXCR4 to attach to the surface of the host T cell. CCR5 receptors are required for HIV binding to macrophages, not CD4 T cells.

Question 7

While the exact mechanism of CD4 T cell destruction in HIV infection is not completely known, what is the cause of the ultimate depletion of CD4 T cells?&#10;A) Stem cell depletion&#10;B) Virus damaged cells are phagocytosed&#10;C) Drugs used to treat HIV deplete CD4 T cells&#10;D) CD8 T cells and NK cells kill all infected cells

Accepted Answer

Eventually bone marrow stem cells cannot produce enough CD4 T cells to replace those that are destroyed by the infection, and then the stem cells cannot properly replenish the stem cell supply and the stem cell pool is depleted, thus depleting the peripheral pool.

Question 8

Which of the following drugs binds directly to HIV reverse transcriptase to inhibit activity?&#10;A) Nevirapine&#10;B) Zalcitabine&#10;C) Raltegravir&#10;D) Didanosine

Accepted Answer

Nevirapine binds directly to HIV reverse transcriptase to inhibit activity, while didanosine and zalcitabine indirectly inhibit reverse transcriptase by incorporation into the DNA chain to cause chain termination. Raltegravir is an integrase inhibitor.

Question 9

Which class of drug results in the formation of disorganized viral capsids that form noninfectious viral progeny?&#10;A) Fusion inhibitors&#10;B) Protease inhibitors&#10;C) Integrase inhibitors&#10;D) Reverse transcriptase inhibitors

Accepted Answer

Protease inhibitors affect proteins that are involved in the formation and assembly of viral capsid and matrix components. Inhibition of protease-mediated cleavage of these proteins results in the formation of viral particles that are noninfectious.

Question 10

The most important enzyme involved in transcription of HIV RNA into DNA is:&#10;A) Integrase&#10;B) RNA polymerase&#10;C) Late phase protease&#10;D) Reverse transcriptase

Accepted Answer

Reverse transcriptase is necessary to the reverse transcription of RNA into first ssDNA and then dsDNA, which can be incorporated into the host genome.

Deck 26: Acquired Immune Deficiency Syndrome