PIP: A group of infectious disease specialists developed an indirect immunofluorescence assay (IFA) to confirm HIV-1 reactivity. They compared its efficacy and cost with those of 2 other HIV serodiagnostic tests to determine whether it would be a feasible confirmatory test in developing countries. In Guinea Bissau, the HIV serodiagnostic test ELAVIA MIXT was used to screen serum samples from 205 people. This test showed that 70% of the samples were seropositive for either HIV-1 or HIV-2. The samples were next tested by the group's IFA (an immunoenzymatic assay using synthetic peptides [PEPTILAV 1.2]) and by then by the Western Blot (WB) test. They used WB as the gold standard. Neither PEPTILAV 1.2 nor the IFA yielded any false positives or false negatives. IFA detected cross-reactivity with HIV-1 in 11 HIV-2 positive serum samples, yet WB did not detect HIV-1 in these 11 samples. The researchers concluded that laboratories in countries with scarce resources and HIV-2 infected individuals, such as Guinea Bissau, should routinely use the more affordable IFA to confirm HIV-positive serum samples.