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ID 6.18


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40 million worldwide (undiagnosed > diagnosed ?)
Worldwide, leading killer of young-mid adults
Majority of people who require treatment do not get it
New HIV Infections
(leading demographic)
Heterosexual women who are minorities
Family, capable of reverse transcription
7 genera, but only concerned w/two: Human T Cell Lymphotrophic Virus and Lentivirus
Genus, includes HIV 1/2 and Simian Immunodeficiency Virus
HIV 1/2
Zoonotic (specifically acquired from primates)
HIV1: Central Africa/chimpanzee SIV
HIV2: West Africa/sooty mangabey SIV
Transmitted to humans ~1930
Envelope (outer membrane protein: gp120; transmembrane protein: gp41)
Nucleocapsid (of p24) contains 2 ssRNAs and RT, integrase and protease
Repeating protein of HIV nucleocapsid (the "p" vs. "gp" should tip you off that it's an internal and non-membrane protein)
"0" for "outer"
It's the outer membrne protein of the HIV envelope responsible for binding CD4+ T cells
Transmembrane glycoprotein of HIV envelope responsible for docking manoever of virion and CD4 T cells
(entry into cell)
gp120 binds CD4 and 1 of 2 coreceptors (CCR5, CXCR4)
CD4 coreceptors required for viral entry into cell
Which coreceptor is implicated in intitial stages of HIV infection?
If abnormal, which coreceptor confers some degree of resistance to HIV?
Which coreceptor is implicated in later stages of HIV infection?
GP-receptor mediated entry into host cell
RT creates dsDNA from ssRNA
Integrase incorporates dsDNA into host geneome
Protease cleaves long, non-functional viral proteins to be assembled into new virions
Even w/HAART, viral reservoirs exist. What are they?
Lymphoid tissue
Dendritic cells
HTLV 1/2
HTLV 1: Endemic in southern Japan and Carribean
HTLV 2: IVDU and some Native American populations
HTLV 1/2
(Transmission route)
ALL VIA INFECTED CELLS (blood, breastfeeding, sexual contact)
HIV works through fluid, NOT HTLV
<5% Will Develop the following . . .
1) Adult T cell Leukemia/Lymphoma (following 30-50 years of latency)
2) HTLV-1 Associated Myelopathy (HAM)
HTLV-1 Associated Myelopathy
Progressive, chronic demyelination of Spinal Cord and CNS white matter
Does NOT wax/wane (unlike MS) but more prevalent in females (like MS)
(Transmission: major points to consider)
Highest frequency of transmission: anal sex
Recipient more at risk of acquiring disease
*Presence of ulcers/STDs heightens risk for transmission
*High viral loads increase chance of transmission
HIV Positive Mothers
(risk of transmitting to child)
Transmission may occur in utero, intrapartum or postpartum
To minimize risk, decrease mom's viral load, do elective caesarean section before membranes rupture and discourage breastfeeding (in developed countries)
Primary Infection
If symptomoatic, Acute Retrovirus Syndrome
High viral load and low CD4
Acute Retrovirus Syndrome
Primary, symptomatic HIV infection
Resembles mono: fever, pharyngitis, lymphadenopathy
HIV: Clinical Latency
Persistent, generalized lymphadenopathy
Constitutional symptoms (fatigue, low grade fevers, diarrhea) and wasting
What predicts immune susceptibility to opportunistic infections?
CD4 Count
CD4 count <200
NOTE: other clinical symptoms (in an HIV positive person) may be used diagnostically to define AIDS
Survival? from < year (Africa) to indefinite (developed countries)
More difficult to transmit w/slower progression
Endemic West African stain (few cases in US)
HIV Transmission: Counseling Pearl
Inform patients with HIV that if they do not practice safe sex, they are at risk for acquiring a SUPERINFECTION (other strains of HIV) which can make them worse!
(1) Enzyme Immunoassay (tests for antibodies to HIV)
(2) Western Blot
Enzyme Immunoassay
Screening test used to determine HIV status
Method: HIV antigens fixed to surface. Wash w/patients serum, followed by enzyme-labeled anti-human antibodies. If bind human Ig, will change color = positive
If positive, a duplicate test is performed
If duplicate is also positive, do a Western Blot
Time frame: will get positive results w/in first 6 weeks post-infection
Western Blot
(1) Viral proteins are run on a gel
(2) Wash gel w/patient's serum
(3) Add enzyme indicator-linked anti-human Ig
Interpreting a Western Blot
Positive: 2+ bands
Indiscriminate: 1 band (must repeat test 1 month later)
Rapid HIV Tests
Basically a hyper-EIA
Positive results should be repeated w/a Western Blot
Takes 20 minutes!
HIV viral load
Measures [viral] plasma
Uses PCR/branched-chain technology
Great predictor of disease progression and effectiveness of therapy
Monitoring a patient w/known HIV
Check CD4 and viral load every 3-4 months
NOTE: even most sensitive test cannot detect <50 copies HIV/mL serum

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