Immunology 2 - HIV infection

Question 1

HIV-2 vs HIV-1

Answer 1

Harder to transmit and less virulent

Question 2

genetic material of HIV-1

Answer 2

RNA, diploid (2 single stranded RNA)

Question 3

How is HIV RNA incorporated in to human genome?

Answer 3

Uses reverse transcriptase to convert RNA to DNA

Question 4

Cells which can be infected by HIV

Answer 4

CD4+ T cells, CD4+ monocytes, CD4+ DCs

Question 5

What is the receptor for the HIV virus?

Answer 5

CD4+ molecules/antigen

Question 6

HIV co-receptor

Answer 6

CCR5/CXCR4

Question 7

What does effective immunity to HIV require?

Answer 7

Antibodies to prevent infection and neutralise virus, and sufficient CD8+ T cells to eliminate latently infected cells

Question 8

Acquired immunity to HIV

Answer 8

Antibodies: anti-gp120 and anti-gp41 (neutralising)

Non-neutralising anti-p24 gag IgG

Question 9

Where are the CD4+ T cells mainly killed in HIV?

Answer 9

In the gut mucosa

Question 10

Effects on other cells of infected CD4+ T cells being anergised by the virus

Answer 10

MO/DC are not activated by CD4+ T cells and cannot prime CD8 + T CELLs
CD8+ T nad B cell responses diminished without CD4+ T cell help
CD4+ T cell memory is lost
Infected MO/DC are killed by CTLs or virus

Question 11

• Replication of the HIV genome is dependent on TWO steps during which errors can occur

Answer 11

1. Reverse transcriptase (RNA –> DNA)
2. Transcription of DNA in to RNA virus

Both low fidelity

Question 12

Does antibody coating of HIV virus stop its infectivity?

Answer 12

no

Question 13

7 main steps of HIV life cycle

Answer 13

1. Attachment and entry
2. Reverse transcription and DNA synthesis
3. Integration
4. Viral transcription
5. Viral protein synthesis
6. Assembly and release of virus
7. Maturation

Question 14

“gravir” which treatment?

Answer 14

integrase inhibitor e.g. raltegravir

Question 15

“avir” which treatment?

Answer 15

protease inhibitor e.g. ritonavir, indinavir

Question 16

Example of attachemnt inhibitor and its target

Answer 16

Maraviroc, CCR5 (RANTES)

Question 17

Median time from HIV infection to AIDS development…

Answer 17

8-10 years

Question 18

Rapid progressors time from HIV –> AIDS

Answer 18

2-3 years (10%)

Question 19

Long-term non progressors

Answer 19

<5%, stable CD4+ counts and no symptoms after 10 years

Question 20

Exposed seronegatives

Answer 20

people who are repeatedly exposed to HIV but do not seroconvert

Question 21

Elite controllers

Answer 21

Can suppress viral replication

Question 22

Long term non progressors host genetic factor

Answer 22

Heterozygosity for 32bp deletion in CCR5

Question 23

LNPs host immune responses factors

Answer 23

Effective cTL and antibody response
Secretion of antibodies that block HIV entry co-receptors
CCR5 –> MIP1a MIP1b, RANTES
CXCR4 –> SDF-1

Question 24

Screening test for HIV

Answer 24

ELISA

Question 25

Confirmatory test for HIV

Answer 25

Western blot

Question 26

How to assess viral load

Answer 26

PCR

Question 27

How is the CD4+ T cell count monitored?

Answer 27

Flow cytometry

Question 28

Antigens on T cells

Answer 28

CD3, CD4, CD8, CD19, CD56

Question 29

2 WAYS to assess HIV ART resistance

Answer 29

Phenotypic (viral replications measured in cell cultures iwth increasing conc of ART)
Genotypic (sequence HIV genome)

Question 30

General HAART combination

Answer 30

2 NRTIs + NNRTI or PI

Question 31

When to treat

Answer 31

Treat all immediately if chronic infection confirmed, treat if symptomatic

Question 32

What is tenofovir an example of?

Answer 32

NucleoTIDE reverse transcriptase inhibitor

Question 33

What is zidovudine/AZT an example of?

Answer 33

NucleoSIDE reverse transcriptase inhibitor

Question 34

Example of NNRTI

Answer 34

Efavirenz

Question 35

Example of a fusion inhibitor

Answer 35

Enfuviritide

Question 36

Which HIV drug is a P450 inducer?

Answer 36

Efavirenz

Question 37

Which drugs inhibit P450?

Answer 37

Protease inhibitors e.g. ritonavir, indinavir

Question 38

Big limitation of HAART

Answer 38

Does not eradicate latent HIV-1

Question 39

When =is hIV ELISA/western blot positive?

Answer 39

After 10+ weeks infection