Lec 10 - HIV

Question 1

what is a lentivirus

Answer 1

chronic and deadly diseases characterized by long incubation periods

Question 2

how did HIV-1

Answer 2

immunodeficiency virus from chimpanzees and gorillas
at some point jumped the species barrier
so is zoonotic virus

Question 3

what is HIV-2

Answer 3

restricted to west africa
- slightly more benign than 1
- could still progress to aids
less transmiss
slower progress

HIV 2 binds less efficiently than HIV 1 with the receptor molecule CD4 on the cell surface.

Question 4

why HIV cant be completely sterilised

Answer 4

both 1 and 2 embed their genome into the host genome as a provirus

Question 5

what 2 diseases became common in the 1980s

Answer 5

Kaposi’s sarcoma
Pneumocystis pneumonia

Question 6

why were haemophilliacs starting to get similar diseases in the 1980s

Answer 6

these were people getting regular blood transfusions to aid blood clotting = connection was made that it may be blood borne

Question 7

where in the world do most live with HIV

Answer 7

eastern and southern africa

Question 8

name the immunodominant glycoprotein that studs the virus

Answer 8

gp120

Question 8

what is the receptor cell that gp120 binds to

Answer 8

CD4 cell

Question 9

what protein is the capsid made from

Answer 9

p24 protein

Question 9

what allows the p24 capsid protein to be stbailised

Answer 9

thousands of water molecules

Question 10

how many open reading frames does hiv 1 have

Answer 10

9

Question 11

why might alternative RNA splicing be needed in HIV1

Answer 11

needed to liberate the overlapping reading frames to be expressed

Question 12

3 key polyproteins in HIV1

Answer 12

gag
pol
env

Question 13

which 2 polyproteins overlap

Answer 13

gag and pol
(will either produce gag on its own OR gag and pol together,
never pol on its own)

Question 14

what is products of gag

Answer 14

matrix
capsid
nucleocapsid

Question 15

what is products of pol

Answer 15

key enzymes:
reverse transriptase
integrase
protease

Question 16

what does the protease allow

Answer 16

cleavage of the pol and gag encoded polyproteins

Question 17

what is products of env

Answer 17

gp160
which is cleaved into Gp120 and Gp41
why tf 41 and not 40 doesnt make sense

Question 18

what is LTR portion of genome

Answer 18

LTR regions contain the promoters that trigger transcription
Viral and host trancription factors can bind here

Question 19

6 accessory proteins

Answer 19

TAT
REV
NEF
VIF
VPU
VPR

Question 20

what does TAT do

Answer 20

Trans Activated Transcription:
- binds to a sequence downstream of LTR and stimulates transcription
ALSO
- can be secreted and taken up by non-infected cells where it upregulate CCR5 and CCrX4

Question 21

what is REV

Answer 21

Regulator of Virion’s protein expression
- when REV high = RNA translated for protein synthesis
- when REV low = full length genomic RNA made available for packaging (prevents splicing so it all stays togehter)

Question 22

what is VPU

Answer 22

viral protein U
= plays a role in release of virus through plasma membrane

Question 23

what is VPR

Answer 23

viral protein R - promotes entry of viral DNA (cDNA) into nucleus

Question 24

what process allows NEF to anchor to plasma membrane

Answer 24

myristolation

Question 25

what does NEF do

Answer 25

Negative Regulatory Factor - binds to the CD4 causing it to be endocytosed and destroyed in lysosomes = prevents super-infection of cells AND - prevents MHC Class 1 being presented on the plasma membrane

Question 26

what is Apobec3g

Answer 26

a cell's innate viral protection enzyme = a cytosine deaminase C-->U in viral cDNA causing hypermutation

Question 27

what does VIF do

Answer 27

polyubiquinates ApoBec3G causing it to be degraded in proteosomes