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Is HIV Tridot an ELISA test for HIV / AIDS?

Wednesday, 21 November 2007
Answered by: Dr. Anuj Sharma
Senior Consultant Microbiologist
Sir Ganga Ram Hospital
Delhi
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Q. Is HIV Tridot the same as ELISA test? Or are these two tests different from one another? What does the term ERS (ELISA / Rapid / Spot) mean? Is ERS a single term?

A.  HIV Tridot is a simple and rapid screening test for HIV/AIDS. It is a visual enzyme immunoassay (EIA) to detect antibodies to HIV 1 (against gp120 and gp41) and HIV 2 (against gp36). In this test the HIV antigens are immobilised on a membrane in a special pad, and patients serum is added to it. After a brief incubation period, and washing steps, other reagents are added and the presence of HIV antibodies by a colour change. A positive result is seen as a red dot. It can also be used to differentiate between HIV1 and HIV 2 infection, since the dots for these antigens are at clearly demarcated separate spots on the membrane pad. Traditionally ELISA (Enzyme Linked Immuno-Sorbent Assay) is a microwell test requiring an ELISA reader. However, the distinction is blurring since the newer rapid and simple EIAs have nearly as good a sensitivity as traditional ELISA for diagnosis of HIV/AIDS. The commonest HIV test is the ELISA test. The result of a single ELISA (or Rapid / Spot tests) should never be taken to indicate infection but merely as an indication for repeated tests to confirm the result. The results of any screening test (ELISA / Rapid / Spot) are only presumptive and should not be reported without being validated by a supplemental test. The WHO recommends that ERS always be repeated to confirm the diagnosis, preferably using a different make of test kit. A negative test does not guarantee that a person is not infected where the risk exposure has occurred recently. In blood-banking only donated blood is screened by a single ERS as per recommendations of Govt. of India. Therefore, these results are not used to identify the individuals. In serosurveillance studies, since the positive results of first ERS are validated by a second ERS and not by a supplemental test, these results are also not used to identify the asymptomatic individuals.

A.  HIV Tridot is a simple and rapid screening test for HIV/AIDS. It is a visual enzyme immunoassay (EIA) to detect antibodies to HIV 1 (against gp120 and gp41) and HIV 2 (against gp36). In this test the HIV antigens are immobilised on a membrane in a special pad, and patients serum is added to it. After a brief incubation period, and washing steps, other reagents are added and the presence of HIV antibodies by a colour change. A positive result is seen as a red dot. It can also be used to differentiate between HIV1 and HIV 2 infection, since the dots for these antigens are at clearly demarcated separate spots on the membrane pad. Traditionally ELISA (Enzyme Linked Immuno-Sorbent Assay) is a microwell test requiring an ELISA reader. However, the distinction is blurring since the newer rapid and simple EIAs have nearly as good a sensitivity as traditional ELISA for diagnosis of HIV/AIDS. The commonest HIV test is the ELISA test. The result of a single ELISA (or Rapid / Spot tests) should never be taken to indicate infection but merely as an indication for repeated tests to confirm the result. The results of any screening test (ELISA / Rapid / Spot) are only presumptive and should not be reported without being validated by a supplemental test. The WHO recommends that ERS always be repeated to confirm the diagnosis, preferably using a different make of test kit. A negative test does not guarantee that a person is not infected where the risk exposure has occurred recently. In blood-banking only donated blood is screened by a single ERS as per recommendations of Govt. of India. Therefore, these results are not used to identify the individuals. In serosurveillance studies, since the positive results of first ERS are validated by a second ERS and not by a supplemental test, these results are also not used to identify the asymptomatic individuals.

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