HIV Questions - Skildum

Question 1

What’s a normal CD4 count?

Answer 1

600-1200 cells/uL

Question 2

What’s a normal CD4 count?

Answer 2

600-1200 cells/uL

Question 3

What’s an immunocompromised cell count?

Question 4

What’s an AIDS cell count?

Question 5

What’s a severe AIDS cell count?

Question 6

Viruses are classified by their. . .

Answer 6

. . .Genomic composition, capsid symmetry, presence of envelope.

Question 7

What are the properties of the HIV-1 infectious particle?

Answer 7

-Enveloped
-Has ssRNA genome
-Has icosahedral capsid symmetry
-Carries reverse transcriptase, integrase and protease
-Infects CD4 positive cells
-

Question 8

What’s an immunocompromised cell count?

Question 9

What’s an AIDS cell count?

Question 10

What’s a severe AIDS cell count?

Question 11

Viruses are classified by their. . .

Answer 11

. . .Genomic composition, capsid symmetry, presence of envelope.

Question 12

What are the properties of the HIV-1 infectious particle?

Answer 12

• Enveloped
• Has ssRNA genome
• Has icosahedral capsid symmetry
• Carries reverse transcriptase, integrase and protease
• Infects CD4 positive cells

Question 13

What does the molecular structure of a nucleoside look like?

Answer 13

NO PHOSPHATES = Just Sugar + Base
-Nucleotides have phosphates-
Key structural features of nucleosides: 3’OH and 5’ phosphate on ribose sugar
Ex: thymidine

Question 14

When a CD4 positive lymphocyte’s T cell receptor is activated by antigen, what transcription factor is activated?

Answer 14

NF-kB

Question 15

A mature HIV-1 viral particle contains three functional enzymes within its capsid. Of these three, which two are required for the particle to infect a cell and become a provirus?

Answer 15

Reverse transcriptase - to transcribe genome to dsDNA

Integrase - to insert into the host genome and become a provirus

Question 16

What is protease required for (third protein in the viral capsid)?

Answer 16

To produce infectious particles

Question 17

A 53 yr old female is HIV-1 positive with a CD4 count of 130 cells/uL. She has Kaposi sarcoma lesions on her arms and torso which first appeared one month ago. What is the most likely cause of her Kaposi sarcoma?

Answer 17

Inefficient activation of CD8+ T cells.

Question 18

A patient’s blood was collected and labeled with fluorescent antibodies against CD3, CD4 and CD8. In the dot plot, only CD3 positive cells are shown. What cells are represented by the dots in the upper right quadrant?

Answer 18

Immature T cells!

Question 19

What does the molecular structure of a nucleoside look like?

Answer 19

NO PHOSPHATES
-Nucleotides have phosphates-
Key structural features of nucleosides: 3’OH and 5’ phosphate on ribose sugar

Question 20

38 yr old male immigrant from Cap-Haitien, Haiti presents with dry cough that has persisted for three weeks. He is confirmed to be HIV-1 positive, with levels of CD4 cells and viral RNA consistent with AIDS. Microscopic analysis of induced sputum show P. jirovecii sporozoites. The first line treatment for his pneumonia targets. . .

Answer 20

Sequential steps in tetrahydrofolic acid synthesis (Trimethoprim - Sulfamethoxazole)

Question 21

A 19 yr old male had unprotected sex with a person who was HIV positive. The next day, he asked his family physician whether he had contracted HIV. What test would detect HIV the soonest after exposure?

Answer 21

Sandwich ELISA for p24 antigen

[p24 antigen spikes soon after infection as the virus disseminates systemically]

Question 22

How does an Indirect ELISA work?

Answer 22

The indirect ELISA measures anti-HIV antibodies in a patient’s blood.

• Antigen comes with ELISA kit
  1. Starts with antigen-coated well
  2. Add patients blood (has specific antibody that binds to the antigen)
  3. Wash step
  4. Enzyme-linked antibody binds to specific antibody
  5. Wash step
  6. Substrate is added and converted by enzyme into colored product; the rate of color formation is proportional to the amount of specific antibody

Question 23

How does the Sandwich ELISA work?

Answer 23

It measures HIV antigen (e.g. p24 capsid protein) in a patient’s blood.

• Antibodies come with the ELISA kit.
  1. Monoclonal antibody-coated well
  2. Wash step
  3. Patients blood is added and antigen binds to antibody
  3. Wash step
  4. A second monoclonal antibody, linked to enzyme, binds to immobilized antigen
  5. Wash step
  6. Substrate is added and converted by enzyme into colored product; the rate of color formation is proportional to the amount of antigen.

Question 24

What antibodies appear first in HIV-1?

Answer 24

p24 antibodies

Question 25

25 yr old HIV-1 positive male is on comb. antiretroviral dug regimen, but his compliance has been sporadic. His CD4 count has recently declined to 250 cells/ul. His physician is developing a new treatment plan. In this patient, if 1 in 10^5 viral particles are resistant to Ziduvudine and 1 in 10^6 viral particles are resistant to Iopinavir, what is the probability that a viral particle will be resistant to both Zidovudine and Iopinavir?

Answer 25

1e5 x 1e6 = 1e11

Question 26

38 yr old male immigrant from Cap-Haitien, Haiti presents with dry cough that has persisted for three weeks. He is confirmed to be HIV-1 positive, with levels of CD4 cells and viral RNA consistent with AIDS. Microscopic analysis of induced sputum show P. jirovecii sporozoites. The first line treatment for his pneumonia targets. . .

Answer 26

Sequential steps in tetrahydrofolic acid synthesis

Question 27

What cytokine mediates the Th1 response from activated CD4+ T cells?

Answer 27

IL-2

[IL-2, IL-3, IFN-gamma, TNFalpha, TNFbeta, GM-CSF mediate the Th1 response]

Question 28

An 18 yr old female is infected with HIV-1 and is being treated with multiple drugs including ritonavir. What is ritonavir’s mechanism of antiviral action?

Answer 28

It inhibits a protease required for viral maturation.