HIV - Virus AnOverview Acquired Immunodeficiency syndrome...

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    Human Immunodeficiency  Virus An Overview
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Human Immunodeficiency Virus Acquired Immunodeficiency syndrome first described in 1981 HIV-1 isolated in 1984, and HIV-2 in 1986 Belong to the lentivirus subfamily of the retroviridae Enveloped RNA virus, 120nm in diameter HIV-2 shares 40% nucleotide homology with HIV-1 Genome consists of 9200 nucleotides (HIV-1): gag core proteins - p15, p17 and p24 pol - p16 (protease), p31 (integrase/endonuclease) env - gp160 (gp120:outer membrane part, gp41: transmembrane part) Other regulatory genes ie. tat, rev, vif, nef, vpr and vpu
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HIV particles
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HIV Genome
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Replication The first step of infection is the binding of gp120 to the CD4 receptor of the cell, which is followed by penetration and uncoating. The RNA genome is then reverse transcribed into a DNA provirus which is integrated into the cell genome. This is followed by the synthesis and maturation of virus progeny.
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HIV-1 Genotypes There are 3 HIV-1 genotypes; M (Main), O (Outlayer), and N (New) M group comprises of a large number subtypes and recombinant forms Subtypes - (A, A2, B, C, D, F1, F2, G, H, J and K) Recombinant forms - AE, AG, AB, DF, BC, CD O and N group subtypes not clearly defined, especially since there are so few N group isolates. As yet, different HIV-1 genotypes are not associated with different courses of disease nor response to antiviral therapy. However, certain subgroups may be difficult to detect by certain commercial assays.
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Schematic of HIV Replication
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Clinical Features 1. Seroconversion illness - seen in 10% of individuals a few weeks after exposure and coincides with seroconversion. Presents with an infectious mononucleosis like illness. 2. Incubation period - this is the period when the patient is completely asymptomatic and may vary from a few months to a more than 10 years. The median incubation period is 8-10 years. 3. AIDS-related complex or persistent generalized lymphadenopathy. 4. Full-blown AIDS.
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Opportunistic Infections Protozoal pneumocystis carinii (now thought to be a fungi), toxoplasmosis, crytosporidosis Fungal candidiasis, crytococcosis histoplasmosis, coccidiodomycosis Bacterial Mycobacterium avium complex, MTB atypical mycobacterial disease salmonella septicaemia multiple or recurrent pyogenic bacterial infection Viral CMV, HSV, VZV, JCV
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Opportunistic Tumours The most frequent opportunistic tumour, Kaposi's sarcoma, is observed in 20% of patients with AIDS. KS
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HIV - Virus AnOverview Acquired Immunodeficiency syndrome...

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