Radio immune Western blotting: a possible solution to indeterminate conventional Western blotting results for the serodiagnosis of HIV infections.

Western blot is used worldwide as a confirmatory assay after a positive or doubtful ELISA result in the serodiagnosis of HIV infections. Despite the use of this test some results may be not definitive due to the presence in Western blot of only few or a single band to HIV protein. This result has been defined as indeterminate. To resolve indeterminate results obtained with conventional Western blotting (WB) we used radio immune Western blotting (RIWB), a method capable of detecting antibodies to HIV-1 proteins with greatly increased sensitivity with respect to conventional WB. We used RIWB to perform a retrospective survey on 20 sera belonging to individuals undergoing HIV serodiagnosis (not blood donors) with positive or borderline EIA results, and indeterminate WB results who only later fully seroconverted. Fifteen of the sera tested by RIWB showed a positive result which clarified any doubtful indeterminate WB result; all bands present in conventional WB were enhanced in intensity using RIWB and new bands, absent in the WB assay, were highlighted using RIWB. RIWB may resolve most indeterminate WB results.