HIV Flashcards
How many people living with hiv
37m
HIV closely related to
SIV
Efffect of SIV on chimps
No harm
Humans got HIV from animals how
Bushmeat
HIV is a
Retrovirus
3 parts of a retro virus
Gag: group specific antigen
viral core proteins: MA (matrix), CA (capsid), NC (nucleocapsid)
Pol: polymerase
enzymes: PR (protease), RT (reverse transcriptase), IN (integrase)
Env: envelope glycoprotein
SU (surface), TM (transmembrane)
Retrovirus is
Virus using reverse transcription
Process of retrovirus
Reverse transcrip7on: copying of an RNA template (the viral
genome) into a double-stranded DNA copy.
2. Integration on: covalent insertion of viral cDNA into the genome of the
infected cell, to form the provirus.
HIV1 is tropic for
CD4 expressing cells: helper T cells and macrophages
Modes of HIV sequence diversification
Copying error(drift)
Recombination(shift)
Drift plus shift
Diversification results in
Immune escape drug resistance and phenotypic changes
Different subtypes of related viruses are called
Clads
Regulatory/ accessory protein
• Tat – potent ac7vator of viral transcrip7on
Rev – mediates unspliced RNA nuclear export
• Vif – cri7cal regulator of virus infec7vity
Nef – immune modulator, T-cell ac7va7on, virus infec7vity
• Vpu – immune modulator, virus release
• Vpr – cell cycle, virus nuclear import, resistance modulator
HIV resistance factors internally
Tetherin inhibits release of virus on cell surface
APOBEC3 catalysts C to U mutagenesis and inhibits RT
SAMHD1 suppresses RT in myeloid cells by hydrolysing dNTPS
SERINC interferes with viral entry
Inexorable fall of CD4 cells causes
AIDS
Risk of acquisition by exposure to HIV
Sexual transmission 0.5% (increased by other STDs)
IV drug use (0.67% per needle)
Blood transfusion (90%)
Mother to child: breast milk or at birth (25%)
Main target for acute HIV1 infection
Gut associated lymphoid tissue (GALT)
Normal progresser ?
Most people progress to AIDS in 8-10 years
Rapid progressor
1-3 years progress to aids
Long term nonprogressors
Maintain low level of detectable viral RNA in blood
AIDS free indefinitely
Elite controller
<50 copies of viral RMA
AIDS free indefinitely
Acute in controlled by
Strong 8+ T cell
Neutralising antibodies arise later
T cell responses: solutions + problems
Initial viremia controlled by CD8 cytotoxic T cells, but not cleared
HIV1 mutates and escapes adaptive immunity
Continued T cell activation lead to inflammation
Inflammation leads to immune dysfunction and pathology
Diagnosis of HIV
ELIZA test for anti-p24
Only detects those who are seroconverted (3 months)
