Immunology - HIV infection Flashcards
Using which enzyme does HIV replicate inside cells?
Reverse Transcriptase
How many genes are inside the HIV genome?
9 genes that encode 15 proteins
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 (initial binding)
gp41( conformational change)
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?
by affecting the function of CD4+ T-cells and antigen presenting cells that are required for proper CD8+ T-cell maturation, HIV is able to decrease the circulating pool of effector and memory CD8+ T-cells that are able to combat viral infection
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 (2)?
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?
lacks proof-reading mechanisms from cellular DNA polymerases
Why is HIV mutation within the host problematic (3)?
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 drug classes are capable of inhibiting the action of reverse transcriptase in HIV infection?
- Nucleoside analogues reverse transcriptase inhibitors
- Non-nucleotide reverse transcriptases inhbitors
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?
individuals who are infected with HIV, but control the infection without antiretroviral therapy (ART).
individuals who have been living with HIV for at least 7 to 12 years and have stable CD4+
How can HIV be diagnosed (2)?
anti-HIV antibodies (ELISA) - screening test
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 = viral replication is measured in cell cultures under selective pressure of increasing concentrations of antiretroviral drugs (compared to wildtype)
Genotypic = mutations detected by sequencing amplified HIV genome (limited to sequencing RT and P)
Which drugs make up a HAART regimen?
Three or more ART drugs
