hiv

Question 1

what three polyproteins are synthesised by retroviruses?

Answer 1

gag (group specific antigen), pol (polymerase) and env (envelope glycoprotein)

Question 2

what is reverse transcription?

Answer 2

copying rna template into dna one

Question 3

what enzyme is used to insert the viral cDNA into the host cell genome?

Answer 3

integrase

Question 4

describe budding

Answer 4

virus buds from cell membrane taking parts of the host membrane with it

Question 5

how long is a retrovirus life cycle under permissive conditions?

Answer 5

24 hours

Question 6

HIV is trophic for ___ expressing cells

Answer 6

CD4

Question 7

name 2 cd4 expressing cells

Answer 7

t helper cells, macrophages

Question 8

name the 2 chemokine receptors that HIV must also bind to to enter cell

Answer 8

CCR5 and CXCR4

Question 9

name the 3 enzymatic activities of reverse transcriptase

Answer 9

RNA dependent DNA polymerase
RNAshH (cleaves RNA from RNA/DNA hybrid - degrades viral RNA once transcription has occured)
DNA dependent DNA polymerase - makes double stranded DNA

Question 10

reverse transcriptase can’t proofread, true or false?

Answer 10

true - allows mutations

Question 11

list 4 modes of HIV-1 sequence diversification

Answer 11

copying errors (drift)
recombination (shift)
drift plus shift
post synthesis editing

Question 12

what is the major target tissue in acute HIV-1 infection?

Answer 12

gut associated lymphoid tissue (GALT)

Question 13

what is the effect of hiv on GALT?

Answer 13

in acute infection: virtually all t cells destroyed

immune integrity never recovers

Question 14

What is the progression of a ‘normal progressor’

Answer 14

AIDS in 8 - 10 years

Question 15

what is the progression of a ‘rapid progressor’

Answer 15

AIDS in 1-3 years

Question 16

what is a long-term non progressor?

Answer 16

maintains low levels of viral RNA in blood, but can be AIDS free indefinitely

Question 17

what is an elite controller?

Answer 17

<50 copies of viral rna/ml in blood, remain aids free indefinitely, genetic association with MHC haplotype

Question 18

lower viral set point = ____chance of survival

Answer 18

higher

Question 19

which cells control the acute infection?

Answer 19

cd8 t cells, kill infected cells

Question 20

do antibodies have any effect on viral load?

Answer 20

no

Question 21

name two antibodies produced against to HIV

Answer 21

non-neutralising anti-env abs

neutralising anti-env abs

Question 22

which antibody is produced in some individuals after some time and can neutralise viruses

Answer 22

neutralising anto-env abs

Question 23

how do the viruses directly kill the cells?

Answer 23

syncytia, increased cell permeability, apoptosis

Question 24

how else are t cells depleted?

Answer 24

immune hyperactivation - t cells get activated which makes them more susceptible to infection
homeostatic strain
diminished regeneration of t cell populations - thymic dysfunction, loss of lymphoid tissue, bone marrow dysfunction

Question 25

whats the usual process from HIV diagnosis

Answer 25

ELISA test for anti-p24 antibodies, repeated with different ELISA or western blot if positive. only works after 3 months (seroconversion) negative p24 should be confirmed with RT PCR to detect HIV genomic RNA in blood - can detect HIV before seroconversion

Question 26

Which viral infections are opportunistic for HIV?

Answer 26

HSV, CMV, JC virus

Question 27

what are some opportunistic bacterial infections?

Answer 27

mycobacteria, tb, mai, pneumococcus,

Question 28

what are some opportunistic fungal infections?

Answer 28

pneumocytis carinii, histoplasma, cryptococcus, coccidiodomyces

Question 29

what are some opportunistic protozoal infections?

Answer 29

cryptosporidium, toxplasma, isospora

Question 30

what are some opportunistic tumours?

Answer 30

kaposi's sarcoma, b cell lymphoma, primary cerebral lymphoma, invasive ca cervix

Question 31

why dont ccr5 drug inhibitors work forever?

Answer 31

over time, the virus stops using the ccr5 receptor and starts using the cxcr4

Question 32

what are some actions of hiv drugs?

Answer 32

ccr5 inhibitor (maraviroc), reverse transcriptase inhibitor, integrase inhibitor (raltegravir), protease inhibitors (ritonavir)

Question 33

which combinations are in haart?

Answer 33

2 nucleoside reverse transcriptase inhibitor plus.. 1 non nucleoside reverse transcriptase inhibitor or.. 1 protease inhibitor