History of HIV/AIDSIn 1981 Kaposi’s sarcoma Pneumocystis carinii pneumoniaIn 1983Luc Montagnier and Françoise Barré-Sinoussiisolated retrovirus from lymphadenopathic patients.Named it as lymphadenopathy associated virus (LAV).
History of HIV/AIDSIn 1984Robert Gallo and colleagues, isolated and culturedcertain retrovirus.Named it as human T cell lymphotrophic virus – IIIor HTLV - IIIIn 1986International Committee on Virus Nomenclature give a generic nameHuman immunodeficiency virus (HIV)
StructureSubgroup: lentivirus. Lenti means slow (greek) It is 32000 years old.Family: Retroviridae.Sperical enveloped virus. 90-120nm2 identical +ve sense ssRNA,Three enzymes Reverse transcriptase (RT) Protease (PR) Integrase (IN)
Viral gens and antigenStructural genes Functions Determines the core and shell of the virus. P55 (p15,p18,p24) Gag -p24 detected in the early stage of infection (before antibodies) Codes polymerase reverse transcriptase and protease pol P31,p51,p66 Determines the synthesis of envelope glycoprotein gp160 env - gp120 which forms the surface spike (72) - gp 41 which forme transmembrane protein.Non structural genes FunctionsTat (trans activating gene) Enchance all viral genesNef ( -ve factor gene) Regulates viral replicationRev ( regulator of viral gene) Enchace the expression of structural proteinVif (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 Contain sequence giving promoter, enhancer and LTR sequence integration signals.Viral classification and subtypes M – major N – new O – outlier P – pending
Mode of transmissionTypes 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 Treatment1. Nucleoside and non nucleoside analogues - inhibits reverse transcriptase enzyme.Eg: Zidovudine (Azidothmidine, AZT), Didanosine, Zalcitabine, lamivudine
Treatment2. Protease inhibitors - inhibits protease enzymeEg: sanquinavir, Ritonavir, indinavirHAART(highly active antiretroviral therapy) - combined therapy(Both) - This method is currently used.
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