PERFORMANCE-CHARACTERISTICS OF RECOMBINANT ENZYME-IMMUNOASSAY TO DETECT ANTIBODIES TO HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 (HIV-1) AND HIV-2AND TO MEASURE EARLY ANTIBODY-RESPONSES IN SEROCONVERTING PATIENTS

We investigated the performance of a double-antigen sandwich recombina nt enzyme immunoassay (EIA; Abbott Laboratories, North Chicago, Ill.) and compared it with that of a synthetic-peptide-based EIA (Biochem Im munosystems, Montreal, Quebec, Canada) for the detection of human immu nodeficiency type 1 (HIV-1) and HIV-2 antibodies in 2,321 clinical ser um samples. The results of both EIA methods and Western blot (immunobl ot) were in agreement for 1,046 HIV-1 and 10 HIV-2 specimens from a pa nel of known positives. From a prospective panel of 1,085 specimens, 3 8 proved to be positive by both EIAs and Western blot, 3 were positive by the recombinant EIA only, and 9 were positive by the peptide EIA o nly, for calculated specificities of 99.71 and 99.04%, respectively. O f 180 specimens from a seroconversion panel collected from 77 patients , the results for 170 were in agreement by all antibody testing method s and 10 were found to be repeat reactive for HIV antibodies by the re combinant EIA only. All 10 were initial specimens of seroconverting pa tients; 7 were also reactive for HIV p24 antigen. An examination of fo ur of these sera by radioimmunoprecipitation assay showed gp120 and gp 160 bands in each. Analysis of the anti-Env antibody class in three of these samples showed that one consisted of immunoglobulin M (IgM) onl y and two contained both IgG and IgM antibodies. Although both EIA pro cedures were sensitive and specific in the detection of antibodies to HIV-1 and HIV-2 and both were capable of detecting early antibodies, t he recombinant assay was more sensitive for antibody detection during early seroconversion.