HIV

Question 1

Difference between prevalence and incidence

Answer 1

Prevalence = Cases per population
Incidence = No cases per unit time

Question 2

Approx. new HIV cases per year?
New AIDS per year?
Deaths per year?

Answer 2

45,000
35,000
15,000

Question 3

Until very recently HIV’s origins are typically __% Sexual and __% Affiliated with Drug Use

Answer 3

85% Sexual

15% Drug Associated

Question 4

What race has the most disproportionately high rate of HIV trasnsmission

Answer 4

African American (esp. among women)

Question 5

Leading case of HIV transmission

Answer 5

MSM

Question 6

Why increasing MSM transmission?

Answer 6

Gen X never watched their generation die
Belief that low RNA levels will prevent transmission
Overall increase in MSM STD rate

Question 7

The one cure for AIDS?

Answer 7

Bone Marrow transplant using a donor with a CCR5-delta32 mutation

Question 8

___% of all cases of HIV/AIDS are in Subsaharan Africa

Prevalence there?

Answer 8

70

5%

Question 9

How is HIV transmitted?

Answer 9

Exchange of bodily fluid
Allows for entry of a virus across a mucosal membrane
(or injected parenterally)

Question 10

HIV transmission is documented via which bodily fluids

Answer 10

Blood, Semen, Vaginal Fluid, Breast Milk

Question 11

T or F. Contaminated surfaces may be a high risk for contraction of HIV

Answer 11

F. Virus doesn’t survive in environment.

Drying = Near Zero levels of the virus

Question 12

Only which types of condoms can effectively prevent AIDS transmission

Answer 12

Latex and Polyurethane

No lambskin allowed

Question 13

Who is the higher occupational needle stick risk?

Hep B or HIV

Answer 13

Hep B

Question 14

Three routes of pediatric infection

Answer 14

Transplacental
Infected Birth Canal
Ingestion of Breast Milk

Question 15

How are pediatric infections with HIV avoided?

Answer 15

Universal HIV screening prior to week 36
Treat mom with HAART ( 30->2% transmission)
Cesarean Section decreases risk by half

Question 16

Genetic Info about the HIV virus itself?

Answer 16

Retrovirus related to lentiviruses

Question 17

Difference between HIV-1 and HIV-2

Answer 17

HIV-1 more aggressive
HIV-1 is in US/Central Africa
HIV-2 is in Western Africa and India

Question 18

Important HIV virus Proteins to Remember? Why?

Answer 18

gp120 - Mediates CD4 binding
gp41 - Fusion to cell membranes
p24 - Major caspid protein in the core (diagnostic)

Question 19

Three viral enzymes necessary for HIV reproduction

Answer 19

Protease, Integrase, Reverse Transcriptase

Question 20

HIV has a tropism for what tissues

Answer 20

Hematopoetic, Nervous tissue

Binds CD4 on lymphocytes, macrophages, and Glial cells

Question 21

HIV proliferation is triggered by…

Answer 21

Cell Activation

Multiplication is cytotoxic to the host cell

Question 22

Normal CD4:CD8 Ratio

HIV CD4:CD8 Ratio

Answer 22

2: 1
1: 2

Question 23

In the first few weeks following infection, total body CD4 cells can drop by…

Answer 23

approx 80%

Question 24

Three ways you may see dying T cells in an HIV infection

Answer 24

Normal Death from Negative Selection
Death by cytopathic effect of virus
Killing of infected cells by virus specific T cells

Question 25

What happens to CD8 cells in HIV infection?

Answer 25

Activated by inflammation, die in LN | CD8s in chronic activation will eventually express CD69 and be retained in nodes

Question 26

Approach to HIV treatment

Answer 26

Inhibit Viral Replication | Inhibit activation of already infected cells

Question 27

Which tends to have higher viral load -- genital secretions or plasma

Answer 27

Genital secretions

Question 28

Describe the process of HIV uptake

Answer 28

Virus binds to gp120 on CD4 molecules Exposure of CCR5 or CXCR4 gp41 undergoes a conformational change that causes insertion of fusion peptide.

Question 29

Whats the deal with CCR5 and CXCr4

Answer 29

Gp120 initially binds to CCR5 (prev. in genital dendritic cells), but over the course of infection, Gp120 mutates and matches better with CXCR4 on lymphocytes

Question 30

HIV resistant individuals tend to be homozygoups for what mutation

Answer 30

CCR5

Question 31

What causes the switch from CCR5 to CXCR4? | How can this be delayed?

Answer 31

Switch due to hypervariable regions on gp120 | Inhibitors of viral replication

Question 32

CXCR4 viruses are a cause of....

Answer 32

syncytia formation on lymphoid tissues Rapid loss of lymphoid tissues You're fucked

Question 33

A natural method of blocking viral uptake?

Answer 33

Early on, inflammatory cytokines block CCR5 binding | You're fucked when the switch to CXCr4 occurs

Question 34

Viral reservoir in an HIV patient?

Answer 34

Lymphoid tissue throughout the body | Virus can proliferate in macrophages with minimal cytopathic effect

Question 35

Role of a mucosal vs a follicular dendritic cell in HIV infection

Answer 35

Mucosal -- Entry/Transport | Follicular -- Reservoir

Question 36

Cause of the initial decay in plasma virus? | Cause of slower secondary decay?

Answer 36

1. Virus specific CD8 T cell response | 2. Loss of longer lived viral reservoirs

Question 37

Can HIV proliferate without significant plasma RNA?

Answer 37

Yes, more prolif in lymphoid tissue reservoirs

Question 38

Three main factors contributing to the development of immune deficiency

Answer 38

Loss of CD4 cells Loss of CD8 fxn Evolutionary changes in the virus

Question 39

How do the LNs change over the course of continued loss f immune fxn

Answer 39

Loss of fxn, architecture Enlarged, then CD4 atrophy Later scarred/fibrotic (burn out)

Question 40

What happens with extensive, early loss of CD4 cells from Peyer's patches

Answer 40

Products from gut pathogens are released into the blood stream. Increase in Ag-specific and non-specific activation of cells

Question 41

With chronic activation, CD8 cells eventually express _____, which makes them stick in lymph nodes

Answer 41

CD69 | Even if they weren't stuck in nodes, they'd be pretty crappy without CD4s to get them to turn up

Question 42

Alternate mechanisms for decreased immune fxn

Answer 42

Apoptosis of uninfected cells caused by soluble gp120 bound to CD4 Killing by CD8s specific for gp120

Question 43

The evolution of drug resistant strains of HIV has resulted in what two maxims:

Answer 43

1. Maximal inhibition of virus replication should decrease resistance. 2. Treatment should always include multiple agents