Deck 1: A Case for Evolutionary Thinking: Understanding HIV

Question 1

What does the acronym AIDS stand for?

Answer 1

Acquired Immune Deficiency Syndrome

Question 2

The proteins that enable the HIV virus to bind to cells are typically CD4 and CCR5.On what type of cells are these proteins typically observed?

A) plasma cells
B) dendritic cells
C) effector helper T cells
D) memory helper T cells
E) both C and D

Answer 2

E

Question 3

What is the effect of the ∆32 allele of CCR5 on HIV binding?

A) appears on the surface of CD4 T cells, but the HIV virion is unable to infect the host cell
B) does not appear on the surface of CD4 T cells
C) appears on the surface of the CD4 T cells and inactivates the virion upon binding
D) interferes with binding of the virion to the CD4 receptor protein
E) appears on the surface of the CD4 T cells and causes the virion to lyse upon binding

Answer 3

B

Question 4

HIV-1 is believed to have been transmitted to humans from which of the following organisms?

A) gorillas
B) sooty mangabeys
C) African green monkeys
D) chimpanzees
E) baboons

Question 5

The acronym HIV stands for which of the following?

A) human intercellular virus
B) human immune virus
C) human immunodeficiency virus
D) human immunity virus
E) human immunodeficiency vector

Question 6

The HIV virus contains all of the following components except ________.

A) integrase
B) double-stranded RNA
C) single-stranded RNA
D) reverse transcriptase
E) protease

Question 7

Originally,HIV was thought to be restricted to transmission during homosexual contact between gay men.List other ways in which HIV is currently known to be transmitted.

Question 8

What viral coat protein typically binds first to the CD4 receptor on helper T cells?

Question 9

Which of the following enzymes is responsible for transcribing viral RNA into DNA?

A) RNA polymerase
B) reverse transcriptase
C) DNA polymerase
D) reverse integrase
E) RNA duplicase

Question 10

Tetherin is an important protein produced by the host.What is the function of tetherin in protecting a host cell from HIV?

A) ties maturing virions to the membrane of the host cell, thereby preventing the release of the mature virus
B) binds the virus to the external host cell membrane, thereby preventing the virus from entering the host cell
C) binds the viral RNA to reverse transcriptase, thus preventing synthesis of the viral DNA
D) binds the two viral RNA strands together, thus preventing the transcription of viral DNA in the host cell
E) causes the maturing virions to aggregate together, thus preventing their release from the host cell

Question 11

In what region of the world is the incidence of infection with HIV highest?

Question 12

Which of the following drug categories are used to treat HIV infections?

A) integrase inhibitors
B) protease inhibitors
C) reverse transcriptase inhibitors
D) DNAse inhibitors
E) fusion inhibitors

Question 13

The ∆32 allele of CCR5 is found at the highest frequency in which of the following populations?

A) Africans
B) Japanese
C) North Americans
D) Europeans
E) South Americans

Question 14

HIV-1 Group M is responsible for 95% of human infections.When is it estimated that HIV-1 Group M was transferred to humans?

A) 1980
B) 1960
C) 1930
D) 1995
E) 1900

Question 15

The AIDS phase of HIV infection begins when the concentration of CD4 T cells in the blood drops below what concentration?

A) 2,000 cells per cubic millimeter
B) 1,000 cells per cubic millimeter
C) 500 cells per cubic millimeter
D) 200 cells per cubic millimeter
E) No CD4 T cells are observed.

Question 16

When AZT is used to treat HIV infections,why does resistance to AZT usually develop?

Question 17

Early in the infection with HIV,most virions bind to the host cell using CCR5 as a coreceptor.As the infection progresses,the HIV population evolves to use an alternate coreceptor.What is the alternate coreceptor these X4 viruses utilize?

A) Tetherin
B) CCR5α
C) vpu
D) TRIM5α
E) CXCR4

Question 18

Antibodies and killer T cells recognize HIV or HIV-infected cells by binding to short pieces of viral proteins displayed on the virus or the infected host cell.These short pieces of viral proteins are called ________.

A) coat proteins
B) virosomes
C) proteosomes
D) epitopes
E) episomes

Question 19

In which of the following regions has AIDS killed the largest number of individuals?

A) India
B) Sub-Saharan Africa
C) United States
D) China
E) United Kingdom

Question 20

Coreceptor inhibitors block HIV infection by preventing which of the following?

A) binding of the HIV virion onto the plasma membrane
B) binding of the HIV virion onto the CCR5 receptor
C) binding of the HIV virion onto the gp120 protein
D) degrading the coreceptor so the virion cannot attach
E) binding of the HIV virion onto the CD4 receptor

Question 21

In what host cell protein is the Δ32 mutation found,and what type of mutation is this?

Question 22

If an individual is infected with HIV that goes undetected and untreated,the infection follows a standard clinical course of progression.Explain the three sequential phases of untreated HIV infection,the approximate times over which these phases occur,and the corresponding levels of both HIV RNA and CD4 T cells circulating in the host bloodstream.

Question 23

Explain the phylogenetic relationship between humans,chimpanzees,and monkeys in the transmission of the current predominant deadly strain in humans,HIV-1.

Question 24

What steps are involved in producing the HIV GP120 protein? List all processes and host cellular structures involved from the point of initial infection with viral RNA to the production of the mature virion outside of the host cell.

Question 25

What is the molecular mechanism by which reverse transcriptase inhibitors,such as AZT,prevent viral replication?

Question 26

What is the function of the product of the viral gene vpu in human infections of HIV?

Question 27

Highly active antiretroviral therapies (HAART)have become the treatment method of choice in treating human HIV infections.What is required for a treatment to be classified as HAART,and why have these treatments proven so effective in the treatment of HIV infections?

Question 28

It has been observed that viral particles often revert (back mutate to non-AZT-resistant populations when treatment with AZT is discontinued.What is the most likely reason for this observation?

Question 29

Explain the mechanism HIV uses to avoid destruction by antibodies present in the human immune system.

Question 30

Following long periods of infection with HIV,an X4 strain often evolves.What evolutionary advantage does the X4 strain confer on the viral population,and what specific protein does this strain interact with?