Aani Immuno: HIV & Vaccination COPY Flashcards
What is the genetic make up of HIV?
RNA retrovirus
Which cells does HIV target as hosts?
CD4+ T Helper cells
CD4+ monocytes + dendritic cells
How does HIV bind to the CD4 cells?
It binds via gp120
How does HIV get inside the CD4 cells? (receptor)
Binds to gp41 for conformational change
Which receptors of CD4 cells does HIV use?
gp 120 initial bindind
gp41 conformational change
CCR5 and CXCR4 chemokine receptors
What are the stages of the HIV life cycle that can be targeting for anti-HIV drugs?
- Attachment/Fusion
- Reverse Transcription (DNA synthesis)
- Integration of viral DNA
- Viral transcription
- Viral protein replication/synthesis
- Viral assembly + release
What type of immune responses are initiated to an acute HIV-1 infection ?
Innate response: NK/complement/macrophages
Adaptive response:
- Antibody dependent
- Antibody mediated
What happens in the antibody mediated immune response to HIV?
Neutralising Abs (NtAb) block the T cell receptors: Anti-gp120 Ab and Anti-gp 41 Ab
AND Non-neutralising Abs are used too:
Anti-p24 gag IgG
Why is HIV’s target cell bad news for us?
Because CD4 cells (T cells) are needed for orchestration of immune response. They are needed for class recombination to develop Abs and they control B cell response. They also activate monocytes/dendritic cells
What else happens in the adaptive immune response to HIV apart from Abs?
CD8+ T cells release chemokines to target HIV
Which chemokines does CD8+ T cells release to tackle HIV?
MIP-1a, MIP-1b and RANTES
Describe the structure of the HIV virus?
Diploid genome
Icosahedral (20 faces)
How long does it take to develop AIDS once you have HIV?
8-10 years on average
What CD4 count would be considered a shift from HIV to AIDS?
Below 200 cells/microlitre
Which tests can you do to check for HIV?
- ELISA screening- checks for Anti-HIV Abs
- Western blot confirmation test - detects Anti-Abs
- PCR viral load detection (HIV RNA detected)
- Flow cytometry to detect CD4 count
- Genotypic assay testing for resistant strains (looking at mutations in HIV genome)
- Phenotypic assay testing for resistant strains (looking at HIV replication against increasing drug conc)
What is seroconversion?
The period of time during which Anti-HIV antibodies develop and become detectable
When does HIV seroconversion take place?
Approx 10 weeks after infection
When to treat a HIV patient with symptoms?
ASAP
When to treat a HIV patient without symptoms?
<200 CD4 count
Start thinking about it at <350 CD4
Name a common HAART regimen used?
Truvada: ETE
- Emtricitabine
- Tenofovir
- Efavirenz
What types of drugs make up a HAART regime?
Two Nucleoside Reverse Transcription Inhibitors (NRTIs) and One Protease Inhibitor (or a Non-NRTI)
What are the disadvantages of HAART?
- Doesn’t remove latent HIV-1
- Cost
- Threat of drug resistance
- High pill burden
- S/Es e.g. toxicity
Which HIV drug can you give in pregnancy ?
Zidovudine
Side effect of Zidovudine?
Bone Marrow suppression
GI effects
Fever