Reliable screening anti HIV with a new ultrasensitive ELISA procedure

Based on the competitive principle a new enzyme linked immunosorbent assay (ELISA) was developed for the reliable detection of Anti HIV. By introducing a sequential competitive procedure a detection limit of Anti HIV was achieved, which exceeded Western blot analysis by factor 8 to 16 as measured with dilutions of 14 well characterized sera. The relevance of this ultrasensitive feature could be demonstrated by a sensitivity value of 100% as evaluated by testing a total of 218 confirmed Anti HIV positive sera as well as by clear cut positive results obtained with 3 specimens derived from early stages of HIV infection. Among a total of 1571 Anti HIV negative blood donations only 1 specimen turned out to be repeatable positive without staining of virus specific bands in Western blot. 117 potentially false positive reacting specimens, which tend to show false positive or ambiguous results in commercial ELISAs were all found negative with the ultrasensitive research assay. An interference of rheumatoid factors could not be demonstrated. The new research assay described in this study appears to represent a technique which combines all advantages of the competitive principle, namely excellent specificity and ease of handling and in addition shows a sensitivity, which significantly stands out against current assays and even confirmatory testing with Western blot.