ENZYME-IMMUNOASSAY USING NATIVE ENVELOPE GLYCOPROTEIN (GP160) FOR DETECTION OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 ANTIBODIES

An enzyme immunoassay using the purified native gp160 for the detectio n of human immunodeficiency virus type 1 (HIV-1) antibody was develope d. This assay was determined to be highly specific, since (i) 157 seru m samples that were confirmed negative by Western blot (immunoblot) (W B) were negative, (ii) 41 serum samples from populations with medical conditions that might cause nonspecific assay reactivity were all nega tive, and (iii) all 15 serum samples that showed false-positive reacti ons in one or more commercial HIV-1 screening tests were negative. The assay gave 100% specificity with a randomly selected and unlinked pan el of 1,000 serum samples from healthy blood donors. The sensitivity o f the assay was assessed by testing 238 samples confirmed as HIV-1 ant ibody positive by a standardized WB assay. All 238 serum samples (100% ) were reactive in the native gp160 assay. Tn a dilution panel of 14 w eakly WB-positive serum samples, 7 samples reacted two- to fivefold mo re strongly in the gp160,assay than in a virus lysate-based assay; the remaining 7 samples gave comparable reactivities in the two tests, Th e reactivities of 13 of these 14 serum samples in the gp160 assay were higher than in a commercial enzyme immunoassay that uses a recombinan t envelope protein as the antigen. The native gp160 assay was more sen sitive to identify seroconversion. In a well-characterized panel of se quential blood samples from a seroconverter, the new assay detected an tibodies at least one sample ahead of the other commercial assays test ed.