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Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
Laboratory diagnosis  of hiv infections
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Laboratory diagnosis of hiv infections

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  • 1. BY: Kashif Nadeem Khokhar
  • 2.  • HIV diagnosis (Antibody/Antigen testing) Enzyme Immunoassays (EIAs), Also known as Enzyme-linked Immunosorbent assays (ELISA). • Rapid tests • Western blot (WB)  Early diagnosis in infants • p24  Initiation and monitoring of ART • CD4 • Viral Load
  • 3. Enzyme Immunoassays (EIAs)  Quantitative assay to measure HIV antibodies  Most detect antibodies to HIV-1 and HIV-2  HIV Antigen / Antibody reaction is detected by color change  Intensity of color reflects amount of antibody present in serum.  Some assays can detect both HIV antibody and HIV antigen.
  • 4. (EIAs) – Cont’d  After several incubations and wash steps a color reaction occurs if HIV antibody is present  An automated reader gives a measurement of optical density (presence of color) for each well
  • 5. Western Blot / Line Immunoassays   Used as supplemental test for confirmation (only difficult cases) Detects antibodies to specific HIV antigens on cellulose strip  Issues:  Multiple standards for performance and interpretation Expensive Limited commercial availability  
  • 6. HIV p24 Antigen Core protein of the virus  EIA detects p24 antigen before antibody can be detected  Detected 2 to 3 weeks after HIV infection  Detected about 6 days before antibody tests become reactive  Used for:  Diagnosis of pediatric HIV-1 infections  Blood bank safety (high incidence countries)  Issues:  Level 4 complexity  Properly maintained equipment required 
  • 7. CD4 T-Lymphocyte      CD4 T-lymphocyte Counts are used for: Determining clinical prognosis Assessing criteria for antiretroviral therapy (ART). Monitoring therapy Manual and automated methods  Issues:  Requires high level of technical skill for test performance and interpretation
  • 8. Viral Load  Quantitative molecular assay Which measures amount of HIV in blood products  Used to: Predict disease progression  Assist with deciding when to initiate antiretroviral therapy (ART).  Monitors response to anti-retrovirals 
  • 9. HIV Rapid Tests  Qualitative assay to detect HIV antibodies  Most detect HIV 1 and HIV 2  As reliable as EIAs  Issues:  Small volumes  Validation of use  Appropriate training
  • 10. HIV Rapid Tests: (Advantages) Increases access to prevention and interventions.  Supports increased number of testing sites  Same-day diagnosis and counseling  Robust and easy to use       Test time under 30 minutes Most require no refrigeration None or one reagent Minimal or no equipment required Minimum technical skill
  • 11. Body Fluids Used for HIV Rapid Testing  Serum  Plasma  Whole blood  Oral fluids
  • 12. Three Formats of HIV Rapid Tests  Immuno-concentration (flow-through device)  Immuno-chromatography (lateral flow)  Particle agglutination
  • 13. How Immuno-concentration Works  HIV antibody links to bound HIV peptide antigens forming the color spot HIV-1 peptide Multi-spot Test & Genie-II are two Types of FlowThrough Devices. HIV-2 peptide
  • 14.      Lateral Flow Devices Determine Hema-Strip OraQuick Unigold
  • 15. Reading Results: Determine NonReactive Reactive Sample Pad Test line Control line
  • 16. How Particle Agglutination Works Anti-HIV antibodies bind to the antigen-coated latex particles Antigen Antibody
  • 17. Tests Based On Agglutination Agglutination devices:  Capillus  Serodia 
  • 18. Reading Results: Capillus Non-reactive Weak Reactive Strong Reactive
  • 19. Key Messages  HIV rapid tests can be as reliable as EIA  All tests require attention to training, supervision, and monitoring at points of service.  As testing is expanding and decentralized, training, supervision, and monitoring must follow accordingly and become all the more important.
  • 20. Thank You So Much…..!!!!

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