Deck 29: Human Immunodeficiency

Question 1

The doubly splice mRNAs produced by HIV do not contain the Rev Response Element (RRE).Which of the following explains why they are transported out of the nucleus without the help of the Rev protein?

A) They interact with the small subunit of the ribosome, which transport them out of the nuceus
B) They lack the cis-acting repressive sequences.
C) The exportin protein binds directly to the mRNAs to transport them.
D) The inportin protein binds directly to the mRNAs to transport them.
E) The HIV Rev protein is still required for their export, but it binds to the poly(A) tail instead of the RRE.

Answer 1

B

Question 2

HIV-1 is a member of which of the following subgroups of retroviruses?

A) Acute transforming retroviruses
B) Nontransforming retroviruses
C) Alpharetroviruses
D) Lentiviruses
E) Spumaviruses

Answer 2

D

Question 3

Which of the following is the primary host cell receptor for most of the cell types infected with HIV?

A) DC-SIGN
B) CD8
C) CCR5
D) CD4
E) CXCR4

Answer 3

D

Question 4

What is unusual about how the tat protein from HIV activates transcription from the LTR?

A) It binds to the tat response element as RNA but not as DNA.
B) It binds directly to the cellular RNA polymerase II.
C) It binds to the reverse transcriptase enzyme and enhances its processivity.
D) It binds next to the TATA box and enhances binding of TBP to the LTR.
E) It inactivates the repressor of NF-kB so that this protein can bind to the LTR.

Question 5

The majority of individuals infected with HIV develop AIDS 8-10 years after the initial infection.

Question 6

Which of the following cell types facilitates the initial infection with HIV and helps to transmit the virus across mucosal membranes?

A) Dendritic cells
B) CD4-positive T lymphocytes
C) CD8-positive T lymphocytes
D) B lymphocytes
E) Monocytes

Question 7

Which of the following is NOT a mode of transmission for HIV?

A) Sexual contact.
B) Breast milk.
C) Aerosoled particles.
D) Blood transfusions.
E) Contaminated needles.

Question 8

Which of the following proteins from HIV are synthesized first in an infected cell?

A) Vpr and Vpu
B) Gag and Pol
C) Rev
D) Tat

Question 9

All of the following affect the clinical outcome of an infection with HIV EXCEPT:

A) The level of viral RNA maintained in the person's blood.
B) The route of infection with the virus.
C) The nature of the immune response to the virus.
D) The diversity of epitopes recognized by the immune system.
E) The strain of HIV the person was infected with.

Question 10

Which of the following viruses was thought to have been transmitted to humans and became the source of the HIV-1 pandemic?

A) Sooty-mangaby SIV
B) Chimpanzee SIV
C) African Green monkey SIV
D) Equine infectious anemia virus
E) Feline immunodeficiency virus

Question 11

The Vpr from HIV can cause the infected cell to stall in the G2 stage of the cell cycle.What purpose does this serve for the virus?

A) This is when there are the highest number of ribosomes in the cell.
B) This is when
C) This is when membrane synthesis is at its highest level.
D) This is when transcription levels from the LTR are the highest.
E) This is when the host cell replicates the cellular genomic DNA.

Question 12

The Rev protein from HIV has which of the following functions?

A) It can enter the nucleus of the host cell via the nuclear pore.
B) It binds to a specific RNA sequence in the viral genome.
C) It enhances transport of unspliced viral RNAs to the cytoplasm.
D) It indirectly enhances the translation of the viral mRNAs.
E) Rev has all of the above functions.

Question 13

While most old world monkeys do not appear to suffer any disease when they are infected with SIV, chimpanzees suffer from significant disease when infected with SIV-cpz.

Question 14

The loss of CD4 positive T cells as a result of infection with HIV eventually causes which of the following to happen in an HIV infected person?

A) Loss of immune competency and an increase in other infections.
B) An increase in the number of T cells leading to leukemia.
C) An over activation of the immune system and autoimmune diseases.
D) An increase in the production of cytokines, leading to a "cytokine storm".
E) B cell lymphomas as a direct result of infection of B cells with HIV.

Question 15

Which of the following describes the function of the HIV protein Vif (viral infectivity factor).

A) It enhances the packaging of viral genomes into new virions.
B) It enhances the synthesis of unspliced viral RNA genomes by the cellular RNA polymerase II.
C) It causes the cellular protein APOBEC3G to be degraded in infected cells.
D) It allows the unspliced viral genomic RNA to be transported out of the nucleus.
E) It increases the levels of the gp120/gp41 proteins on the surface of infected cells.

Question 16

Which of the following lymphoid tissues is the first to be depleted by infection with HIV-1?

A) Thymus gland
B) Spleen
C) Lymph nodes
D) Tonsils
E) Gut associated lymphoid tissue

Question 17

HIV, unlike most other retroviruses, can infect nondividing cells.Which of the following explains why?

A) The HIV reverse transcriptase enzyme can function with a lower concentration of nucleotide triphosophates.
B) The HIV integrase enzyme can work without the help of cellular enzymes.
C) The HIV matrix protein can direct the nuclear import of the HIV preintegration complex.
D) The HIV Vpr protein can interact with cellular microtubules to bring the virion close to the nucleus.
E) All of the above are correct.

Question 18

The Vpu protein from HIV increases the release of newly synthesized virus particles from the surface of infected cells.Which of the following describes the mechanism by which Vpu does this?

A) It degrades the sialic acid residues on the surface of the cell, which the virions can bind to.
B) It induces the degradation of the protein tetherin, which keeps the virions attached to the cell surface.
C) It increases the number of CD4 proteins to be exported to the cell surface.
D) It causes the plasma membrane to become flexible and fold around the budding virion.
E) It increases the export of gp120 and gp41 to the cell surface.

Question 19

During the first two to six weeks after infection with HIV, most people do not have any symptoms of infection.

Question 20

The Nef protein from HIV causes a reduction in the amount of the MHC 1 protein on the surface of infected CD4 positive T cells.Which of the following is the result of this process?

A) It prevents antibodies from binding to the viral proteins on the cell surface.
B) It increases the amount of infectious virus released from the T cells.
C) It increases the amount of virus that can bind and infect the T cells.
D) It prevents the immune system from detecting that the T cells are infected.
E) It causes the cytotoxic T cells to attack and kill the HIV infected T cells.

Question 21

During the clinical latency period of an HIV infection, the virus is not replicating and no virus particles are produced.

Question 22

Monkeys infected with a mutant of SIV that lacks the Nef coding sequence have reduced virus titers and less severe disease.

Question 23

People who have a natural mutation in the gene encoding the CCR5 protein are resistant to infection with HIV.

Question 24

Describe the clinical progress of an HIV infection in a typical patient who has not been treated with anti-HIV drug therapy.What are the other two potential disease courses, which occur in a minority of individuals, that could result from infection with HIV?

Question 25

After treatment for ten years with highly active anti-retroviral drugs, most HIV infected patients can stop taking the medications and are considered cured.

Question 26

Describe three unique aspects of HIV's biology that make it an extremely difficult virus for the human immune system to eliminate.