EVALUATION OF A QUANTITATIVE DOUBLE ELISA STRATEGY FOR CONFIRMATION AND DIFFERENTIATION OF HIV-INFECTION

The current HIV pandemic is complicated by the spread of distinct type s and subtypes of HIV. The currently used conventional diagnostic test s have shown limitations in the detection of antibodies against all HI V-1 subtypes, as demonstrated by recent identification of HIV-I subtyp e O. To evaluate quantitatively the diagnostic potential of a double E LISA strategy for the detection and partial differentiation of HIV-1, HIV-I subtype O and HIV-2 infections blood samples were examined at fi ve different test centers: Blantyre, Malawi; Abidjan and Daloa, Ivory Coast; Yaounde, Cameroon, Munich, Germany. All tests results, includin g ELISA extinction values and Western blot profiles, were forwarded to Munich for final interpretation. An indirect anti-HIV-1/2 ELISA and a competitive anti-HIV-l ELISA were used in combination for the initial screening of blood specimens. All anti-HIV positive and anti-HIV nega tive samples were subjected to immunoblot analysis. Independent of the diversity of the extinction profiles, and of the test manufacturer, t he quantitative evaluation of the ELISA extinction values could define two extinction areas with a 100% predictive value for HIV-I seroposit ivity and HIV seronegativity: extinction values >2 by the indirect ELI SA and <0.2 by the competitive ELISA for an anti-HIV-l subtype A to I positive result; extinction values <0.2 by the indirect ELISA and >1.0 by the competitive ELISA for an anti-HIV negative result. Additionall y, the quantitative evaluation of the extinction profile provides part ial information on the HIV-1 subtype as far as the distiction in group M and group O is concerned. In conclusion, the quantitative evaluatio n of this double ELISA strategy can reduce the number of blood specime ns that require additional confirmatory testing in developing countrie s and can be superior to the immunoblot method during early seroconver sion. (C) 1997 Elsevier Science B.V.