HIV Virology

Question 1

HIV gemone

Answer 1

2 copies of (+)-ssRNA

Question 2

HIV capsid symmetry

Answer 2

Icosahedral

Question 3

Is HIV enveloped?

Answer 3

Yes

Question 4

Why does HIV require intimate contact to be transmitted?

Answer 4

Enveloped

Question 5

Tropism for HIV virus?

Answer 5

CD4+ T cells (also CD4+ monocytes and macrophages)

Question 6

3 enzymes that HIV carries

Answer 6

Reverse transcriptase
Integrase
Protease

Question 7

Reverse transcriptase

Answer 7

Converts ssRNA to DNA

Question 8

Integrase

Answer 8

Cuts the host DNA for viral DNA to insert

Question 9

Protease

Answer 9

Not as important in establishing infections but modifies viral encoded proteins to make new particles

Question 10

Why is protease so important?

Answer 10

HIV genome is very small and compact. Genes are encoded on multiple overlapping reading frames.

Question 11

3 important genes in HIV

Answer 11

gag
pol
env

Question 12

gag and env

Answer 12

make one big peptide (for structure), cleave with protease to make desired structural proteins

Question 13

gag protein

Answer 13

capsid proteins (p24)

Question 14

pol

Answer 14

reverse transcriptase, protease and integrase

Question 15

env

Answer 15

envelope glycoproteins gp120 and gp41

Question 16

LTRs

Answer 16

Integration sites; bind host transcription factors NF kB, Sp1, TBP

Question 17

Nef, vpr, tat, rev

Answer 17

transcription factors to regulate host machinery to fit viral preferences (not in proliferates)

Question 18

5’ to 3’ have LTRs that…

Answer 18

interact with integrase to allow viral genome to insert to host DNA –> promotes NFkB

Question 19

The binding of infectious particle to the host cell is initiated by..

Answer 19

interaction between gp120 and CD41

remember gp120 is outer membrane

Question 20

Along with gp120/CD41 - This interaction is required to initiate infection

Answer 20

Host chemokine receptor (either CXCR4 or CCR5) and gp41

Question 21

What does CXCR normally bind to?

Answer 21

Stromal derived factor 1

Question 22

Stromal derived factor in HIV

Answer 22

Occupies HIV-1 binding site and blocks infection

SDF-1 polymorphisms may be associated with natural resistance to HIV-1 infection

Question 23

SDF-1 in healthy cells

Answer 23

binds CXCR4 on lymphocytes and directs their homing to tissues

Question 24

Steps in HIV-1 infection cycle

Answer 24

1. Binding of HIV1 envelope proteins to host receptors
2. Envelope fusion with plasma membrane
3. Reverse transcription to dsDNA
4. Integration
5. Expression of viral genes to make viral proteins and viral genome
6. Proteolytic processing of viral proteins
7. Assembly of viral particles and budding from host cell

Question 25

What do Rev nev and tat do?

Answer 25

promote NFkB (remodels cell)

Question 26

What is the significance of Rev?

Answer 26

Threshold marker Unspliced RNA - encode structural proteins (capsid envelope and enzymes) Spliced RNA - ready to go

Question 27

Proviral stage

Answer 27

Virus causing host cell to produce viral proteins Envelope expressed on plasma membrane (before protease) Latency

Question 28

HIV-1 infected T cells express ____ on their cell surface

Answer 28

env proteins

Question 29

Binding of env to CXCR4 induces _____

Answer 29

autophagy and apoptosis

Question 30

Viral opportunistic infections with HIV

Answer 30

Kaposi sarcoma virus (KSV, HHV-8) | Cytomegalovirus (CMV, HHV-4)

Question 31

CMV and HIV

Answer 31

severe blindness, encephalitis

Question 32

Fungal infections and HIV

Answer 32

Candida (oral thrush)

Question 33

Protozoa and HIV

Answer 33

Cryptococcus | Pneumocystis

Question 34

What is the first thing to detect/monitor upon exposure

Answer 34

p24 antigen

Question 35

p24 is a capsid protein encoded by _____

Answer 35

gag

Question 36

As CD4 levels fall, viral genome ____

Answer 36

increases

Question 37

AIDS

Answer 37

CD4+ falls below 200

Question 38

Diagnostic tests for HIV

Answer 38

ELISA followed by Western Blot

Question 39

ELISA looks for...

Answer 39

p24 antibody (some look at antigen)

Question 40

Monitoring patients with HIV

Answer 40

CD4+ T cell enumeration by flow cytometry | Polymerase chain reaction, viral RNA or DNA

Question 41

The goal of therapy for patients with HIV

Answer 41

Reduce the level of circulating virus

Question 42

Low viral load

Answer 42

Increased life span

Question 43

High viral load

Answer 43

shorter life span