The use of radioimmune western blotting to evaluate indeterminate western blotting results in blood donor HIV serodiagnosis.

The serodiagnosis of HIV infection is sometimes puzzling due to questionable "indeterminate" results obtained by western blotting (wb), the confirmatory test used world-wide after a positive or borderline ELISA result. These situations cause anxiety in the person being tested and determine additional laboratory costs. We showed that radioimmune western blottting (riwb) an improved and sensitive modification of conventional wb, was able to resolve most "indeterminate" results in individuals who later fully seroconverted. We report in this paper the use of riwb in sera of 20 uninfected blood donors with an indeterminate wb continuing for at least 6 years, to verify the serological status in indeterminate not at risk individuals. Thirteen out of the 20 were indeterminate with conventional wb due to the presence of antibodies to p 24, two to p 17, two to p 55, two to p 51 and p 55 and one to p 24 and p 51 antibodies. The presence of all these bands was confirmed using riwb; moreover, in comparison with wb, the intensity of all bands was clearly enhanced. Despite the use of this highly sensitive method no new bands were found with riwb in indeterminate sera; negative results were obtained when sera borderline or positive with ELISA but negative with wb, were subjected to riwb.