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بسم الله الرحمن الرحيم

بسم الله الرحمن الرحيم. Detection of HIV infection In : Medical, health and social aspects of HIV/AIDS. Sayad B. M.D, MPH 2003. HIV structure:. 1-Core: Genome,Pr.,Enz. 2-envelope: Host C.M. ,Pr. HIV genom:. 1-env: gp41,gp120,gp160 2-gag: p7,p9,p17,p24 3-pol: p11, p66,p32,p51.

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بسم الله الرحمن الرحيم

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  1. بسم الله الرحمن الرحيم Detection of HIV infection In : Medical, health and social aspects of HIV/AIDS Sayad B. M.D, MPH 2003

  2. HIV structure: 1-Core: • Genome,Pr.,Enz. 2-envelope: • Host C.M. ,Pr

  3. HIV genom: 1-env: • gp41,gp120,gp160 2-gag: • p7,p9,p17,p24 3-pol: • p11, p66,p32,p51

  4. HIV typing: • HIV1: • Group: M (Include eight subgroup or clad:A,B,C,…) • Group: O • Group: N • HIV2

  5. HIV life cycle: • Replication products: • Structural Pr. • HIV RNA • Proviral DNA

  6. HIV infection trend: • Direct assays in first 2-8 W. • Serologic assays after 8W.

  7. Laboratory assays for HIV detection: 1.Serologic assays 2.Direct assays

  8. Serologic assays: • Advantages • Disadvantages • Kinds of serologic assay: 1-ELISA 2-Western blot

  9. ELISA: • Methodology • Sensitivity :99% • Specificity :99%

  10. Causes of false negative ELISA for HIV infection: • Primary HIV infection • Immunosuppressed patient • Errors in specimen labeling or handling • HIV2 infection

  11. Causes of false positive ELISA for HIV infection: • Human error • Hemodialysis • Reactive rapid plasma reagin test • Autoimmune disorders • Multiple myeloma • Hemophilia • Alcoholic hepatitis • Rabies vaccination • Influenza vaccination • Viral infections

  12. Western blot: • Methodology • Sensitivity :> 90% • Spesificity :>99%

  13. Causes of false negative western Blot for HIV infection: • 20% of HIV2 positive sera • 10% of HIV1 group O sera

  14. Causes of false positive western Blot for HIV infection: -Hyperbilirubinemia -Connective tissue disorders -Polyclonal gammopathies

  15. Answer the questions: 1.Who is HIV-positive? 2-Why do we repeat ELISA? 3.Why do we perform W.B after positive double ELISA?

  16. Predictive value: PPV=a/a+b

  17. What do you do in the following conditions: 1.First ELISA(HIV1/HIV2) is negative? 2.First ELISA(HIV1/HIV2) is positive and the second is negative? 3.Double ELISA(HIV1/HIV2) is positive and W.B is negative? 4.Double ELISA(HIV1/HIV2) is positive and W.B is indeterminate?

  18. Direct assays: • Advantages • Disadvantages • Kinds of direct assays: • P24 Ag detection • Proviral DNA detection • HIV-RNA DETECTION • HIV-culture

  19. P24 Ag detection: • Methodology • Sensitivity: • Acute inf : 50-75% • Asymptomatic: 4% • AIDS: 70% • Specificity: >90%

  20. Proviral DNA detection: • Methodology • Sensitivity : 95% • Specificity : 98%

  21. HIV-RNA detection: • Methodology • Sensitivity : >95% • Specificity : >90%

  22. HIV culture: • Methodology • Sensitivity : per case • Specificity :100%

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