ANTI-HIV ANTIBODY TITER - AN ALTERNATIVE SUPPLEMENTARY TEST FOR DIAGNOSIS OF HIV-1 INFECTION

The diagnosis of HIV infection is based on screening of HIV antibodies and confirmed by a more specific supplementary test. The most common confirmation test is Western blot, which is expensive, time consuming and subject to technical skill. The present study was carried out to e valuate whether the anti-HIV-1 antibody titer is valid as a supplement ary test for diagnosis of HIV-1 infection. Anti-HIV-1 antibody titers of 2,414 anti-HIV-l positive sera determined by the particle agglutina tion (PA) method were analysed in comparison with the Western blot ana lysis. The Western blot negative result was found in 11 of 2,414 (0.46 %) anti-HIV-l positive sera, these sera also gave negative anti-HIV by ELISA. The PA titers of these sera were found in the range of 16 to 6 4. Seventeen samples (0.70%) with anti-HIV-l in the titer range of 16 to 256 showed indeterminate Western blot analysis. The rest, 2,386 of these 2,414 sera (98.84%), were shown to be positive by Western blot. However, all of the 2,356 sera with antibody titers greater than or eq ual to 512 (97.6%) demonstrated positive Western blot results. Five ca ses among the 17 (29.4%) indeterminate sera were examples of early ser oconversion of HIV infection, which were confirmed in follow up specim ens. The results suggest that only the samples with antibody titers < 512 are required to be confirmed for HIV infection by Western blot. It is possible that early seroconversion may be inferred from anti-HIV t iters. Therefore, in order to reduce time and cost, the PA anti-HIV ti ter can be used as an alternative supplementary test for diagnosis of HIV-1 infection in most positive screened anti-HIV samples. Western bl ot is needed for testing in only a few cases.