HIV Flashcards
HIV
human immunodeficiency virus
HIV1 HIV2
HIV1 = retrovirus responsible for most HIV infections HIV2 = similar illness but has a longer latent period
how many people HIV +ve in the world
30 mil
2.5mil/yr
2mil deaths/yr
most in africa
Immunology
HIV binds via its gp120 envelope to CD4 receptors on helper t lymphocytes, monocytes, macrophages and neural cells
CD4 +ve cells migrate to lymphoid tissue where the virus replicates = billions of new virions which infect more CD4 +ve cells
impaired function or deletion of CD4 cells = decrease in immune func
virology of HIV
RNA retrovirus - 9 subtypes
after cell entry viral reverse transcriptase makes a DNA copy of the RNA genome
viral integrase enzyme then integrates this into DNA host
the core viral proteins are synthesised as polypeptides to make the building blocks of the virus
viral load
the number of circulating viruses (viral load) predicts progression to AIDS
acute primary infection
seroconversion
transient immunosuppression and fall in CD4 count followed by rise
acute rise in viral load then fall to set point
symptoms: fever, malaise, myalgia, pharyngitis, maculopapular rash
phase 2 infection
- asymptomatic phase (years)
progressive loss of CD4 T cells resulting in poor immunity, clinical latency (+/- progressive generalised lymphadenopathy) - Early symptomatic HIV (‘AIDs related complex’)
phase 3 infection
AIDS!!!
symptoms of immune deficiency
CD4
PGL
persistent generalised lymphadenopathy
nodes >1cm diameter and 2 or more extra inguinal sites persisting for >3mo
what are AIDs related symptoms?
inc temp night sweats diarrhoea decreased weight minor opportunistic infection eg oral candida, herpes zoster
AIDS CD4 count
CD4
HAART
highly active antiretroviral therapy
Diagnosis HIV
serum or salivary HIV antibodies by ELISA
if recent infection?
HIV-antibodies might be negative
check for HIV RNA (PCR) or core p24 protein antigen in plasma
or repeat ELISA 6w and 3mo
which subtypes common in UK
A and B
which subtype common in Africa
D
which types have a worse prognosis
hybrid / recombinant types as they bind to immune cells more readily
HIV prevention
blood screening
disposable equipment
antenatal retrovirals if HIV +ve and C sec bith and bottle feeding
PEPSE - post exposure prophylaxis following sexual exposure
HAART rx as protection
behavioural - sex ed, reduce freq of partner change, condom use
TB and HIV
if pt has cough, fever, night sweats or weight loss they have TB until proven otherwise
long term non progressors
those infected with the virus but dont get ill as they have alterations in immune system which are protective
where does the virus often sit latent for a long time
genital tract
CNS
GI system
bone marrow
UN AIDS aim
90/90/90 goals
90% of people living with HIV being diagnosed
90% diagnosed on antiretroviral therapy (ART)
90% viral suppression for those on ART by 2020
AIDS
latent period?
acquired immune deficiency syndrome
latent period 5-10 y - HIV2 slower / long term non progressors can be longer
more rapid in rapid progressors, children and elderly
