HIV

ByR.Parthasarathy

History of HIV/AIDSIn 1981

Kaposi’s sarcoma Pneumocystis cariniipneumoniaIn 1983

Luc Montagnier and Françoise Barré-Sinoussi isolated retrovirus from lymphadenopathic patients.

Named it as lymphadenopathy associated virus (LAV).

History of HIV/AIDSIn 1984

In 1986

Robert Gallo and colleagues, isolated and cultured certain retrovirus.

Named it as human T cell lymphotrophic virus – IIIor HTLV - III

International Committee on Virus Nomenclature give a generic name

Human immunodeficiency virus (HIV)

StructureSubgroup: lentivirus.

Lenti means slow (greek)

It is 32000 years old.

Family: Retroviridae.

Sperical enveloped virus. 90-120nm

2 identical +ve sense ssRNA,

Three enzymes

Reverse transcriptase (RT)

Protease (PR)

Integrase (IN)

Viral gens and antigenStructural genes Functions

GagDetermines the core and shell of the virus.P55 (p15,p18,p24) -p24 detected in the early stage of infection (before antibodies)

pol Codes polymerase reverse transcriptase and proteaseP31,p51,p66

envDetermines the synthesis of envelope glycoprotein gp160 - gp120 which forms the surface spike (72) - gp 41 which forme transmembrane protein.

Non structural genes FunctionsTat (trans activating gene) Enchance all viral genes

Nef ( -ve factor gene)Rev ( regulator of viral gene)

Regulates viral replicationEnchace the expression of structural protein

Vif (viral infectivity factor) Influence infectivity of viral particles.

Vpu and vpx (1&2) Enchance maturation and release of virus

Viral gens and antigenNon structural genes Functions

vpr Stimulate promoter region

LTR sequence Contain sequence giving promoter, enhancer and integration signals.

Viral classification and subtypes

M – majorN – newO – outlierP – pending

Mode of transmission

Types of exposure Chance of infection per exposure(ApproX)

Blood and blood products >90%Tissue and organ donation 50-90%Sexual transmission 0.1 – 1.0%Through injections and injuries 0.5 – 1.0%Mother to fetal baby 30%

Clinical symptoms are classified as mentioned below:

Lab dignosis

Screening, measuring the antibodies to Hiv using ELISA

Confirmed by western Blot

Treatment

1. Nucleoside and non nucleoside analogues - inhibits reverse transcriptase enzyme.

Eg: Zidovudine (Azidothmidine, AZT), Didanosine, Zalcitabine, lamivudine

2. Protease inhibitors

- inhibits protease enzyme

Eg: sanquinavir, Ritonavir, indinavir

HAART(highly active antiretroviral therapy)

- combined therapy(Both)

- This method is currently used.

Treatment

References

• Anathanarayan and paniker’s, Text book of microbiology, 7th edition.

• Sherrai medical microbiology, 5th edition.• Net sources

www.avert.com

www.cdc.gov

www.unaids.org