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HIV ANTIBODY TESTING. HIV INFECTION. triggers an HIV antibody production in an HIV-infected person’s blood. HIV INFECTION. is diagnosed largely by the detection of antibodies against HIV in the blood of infected patients. HIV ANTIBODY TEST.
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HIV ANTIBODY TESTING
HIV INFECTION triggers an HIV antibody production in an HIV-infected person’s blood
HIV INFECTION is diagnosed largely by the detection of antibodies against HIV in the blood of infected patients
HIV ANTIBODY TEST is a blood test which looks for HIV antibodies
MEDICAL tECHNOLOGISTS cLINICALlABORATORY
Screening Test Enzyme Linked Immunosorbent Assay (ELISA) Rapid Test Confirmatory Test Western Blot Assay
Enzyme Linked Immunosorbent Assay (ELISA) Screening Test
Spectrophotometer Spectrophotometer
elisa Chromogen or substrate para-nitrophenyl phosphate (PNPP) Anti-human immunoglobulin coupled to an enzyme alkaline phosphatase or horse radish peroxidase Patient’s HIV antibody Inactivated HIV antigen POSITIVE NEGATIVE
False Positives ● False Negatives ● People (especially women who have had multiple pregnancies) may possess antibodies directed against human leukocyte antigens (HLA) HLA are present on the host cells used to propagate HIV. As HIV buds from the surface of the host cell, it incorporates some of the host cell HLA into its envelope Window period (seroconversion)
Rapid Test Screening Test
Rapid test Inactivated HIV antigen Patient’s HIV antibody Conjugate Color development reagent
Advantages quicker to perform do not require batching do not require specialized equipment results delivered on the same day *Only ‘WHO recommended’ rapid HIV antibody tests should be used to ensure quality
Western Blot Assay confirmatory Test
Viral proteins that confirm HIV positivity
Western blot Substrate solution • Strips are washed with distilled water BCIP+NBT 5-Bromo-4-Chloro-3'-Indolyphosphate p-Toluidine Salt and Nitro-Blue Tetrazolium Chloride Color Reaction (10-15 minutes incubation) Anti-human immunoglobulin conjugated with an enzyme Wash 4 times for 5 minutes each alkaline phosphatase or horse radish peroxidase 2nd Incubation (1 hour) Patient’s antibody to specific HIV viral proteins Wash 3 times for 5 minutes each 1st Incubation (Overnight) Specific HIV viral proteins gp160 viral envelope precursor (env) gp120 viral envelope protein (env) binds to CD4 p31 Reverse Transcriptase (pol) P24 viral core protein (gag)
Western blot *Insoluble black-purple bands develop at the sites on the test strip occupied by antibodies Specific HIV viral proteins gp160 viral envelope precursor (env) gp120 viral envelope protein (env) binds to CD4 p31 Reverse Transcriptase (pol) P24 viral core protein (gag)
Criteria for the band pattern interpretation of HIV Western Blot test established by the Centers for Disease Control with several other organizations in 1987
What is an Indeterminate HIV Result? A neither positive nor negative result.
What happens if one has an Indeterminate HIV Result? ● ● return for follow up testing counsellors can serve as one’s support in this stressful period
“A person infected by HIV/AIDS is Jesus among us. How can we say “no” to Him? ” - Mother Teresa of Calcutta Bro. John Jay C. Magpusao, MI RMT, MA Theology Order of the Ministers of the Infirm (Camillians)