Immunology 4 - HIV infection Flashcards
Using which enzyme does HIV replicate inside cells?
Reverse Transcriptase
How many genes are inside the HIV genome?
9
What is the role of reverse transcriptase in HIV?
Converts RNA into DNA which can be incorporated into host cells’ genes
What are the two key glycoproteins encoded by the HIV virus?
gp120
gp41
Which cell of the immune system is particularly affected by HIV?
CD4+ T cells
Recall the receptor and co-receptors for HIV on CD4+ T cells
CD4 receptors
CCR5 CXCR4 coreceptors
In people who have natural immunity to HIV, what antibodies may be present in serum?
Anti-gp120 and anti-gp41 (Nt) antibodies
How does HIV infection affect CD8+ T cells?
Interferes with activation, as CD4+ T cell and antigen-presenting cell help are not present due to the virus
How does HIV infection affect monocytes and dendritic cells?
Not activated by CD4+ T cells and so cannot prime naive CD8+ T cells
How does HIV affect immunological memory?
CD4+ T cell memory is lost
CD8 memory cell not activated by antigen-presenting cell
Why is there so much variation/mutation in HIV infection?
HIV lacks same checking mechanisms in DNA transcription
Why is HIV mutation within the host problematic?
Escape from neutralising antibodies.
Escape from HIV-1-specific T cells.
Resistance and escape from antiretroviral drugs.
Recall the 7 steps of the HIV life cycle
- Attachment/Entry
- Reverse Transcription and DNA Synthesis
- Integration
- Viral Transcription
- Viral Protein Synthesis
- Assembly of Virus and Release of Virus
- Maturation
Which drugs are capable of inhibiting the action of reverse transcriptase in HIV infection?
- Nucleoside analogues
2. Non-nucleotide reverse transcriptases
Which class of HIV drugs can prevent integration of viral DNA?
Integrase inhibitors
Which HIV drugs can prevent modification of translated viral proteins?
Protease inhibitors
What is the median time of infection with HIV to AIDS development?
8-10 years
What does it mean if someone is an HIV exposed seronegative individual?
Partner of individual with HIV who remains uninfected
What are the 3 major markers used to monitor HIV?
CD8
CD4
Plasma viral load
What is long-term nonprogression of HIV?
Individual who is asymptomatic 10 years after infection
How can HIV be detected?
anti-HIV antibodies (ELISA)
Viral load (PCR) - more sensitive
ELISA = screening
Western Blot = Confirmatory test
How are CD4+ T cell levels measured in HIV infection?
Flow cytometry
What are the two methods of testing for ARV resistance?
Phenotypic
Genotypic (involves directly sequencing the amplified genome)
Which drugs make up a HAART regimen?
Three or more drugs + one or more binding agents
When should HAART treatment be initiated?
Immediately
Give 2 examples of NRTI HIV drugs
Zidovudine
Lamivudine
Recall 2 examples of protease inhibitor HIV drugs
Tenofovir
Truvada
What class of drug is raltegravir?
Integrase inhibitor
Which drugs make up the HAART regimen initially?
2 NRTIs + PI
What CD4 count defines AIDS?
<200 cells/ nanolitre
Which drugs make up the atripla pill?
Emtricitabine + tenofavir + efavirenz
Which ARV is best to use in pregnancy?
Zidovudine
How can CD8+ T cells provide HIV entry into cells?
Producing chemokines MIP-1A, MIP-1b and RANTES
