Journal of Virological Methods, 4 1 (I 993) I 8l-l 92 0 1993 Elsevier Science Publishers B.V. / All rights reserved / Ol66-0934/93/$06.00 I81 VIRMET 01435 Enzyme-linked immunosorbent assays for the measurement of human immunodeficiency virus, type 1 reverse transcriptase antigen and antibodies Clive Loveday and Richard S. Tedder Division of Virology, Department of Medical Microbiology. University College and Middlesex School of Medicine, London (UK) (Accepted 8 September 1992) zyxwvutsrqponmlkjihgfedcbaZYXWV Summary Enzyme-linked immunosorbent assays (ELISA), using recombinant HIV-l reverse transcriptase (RT; p66), are described for the measurement of RT antigen and serum antibodies to RT (anti-RT). The ELISA for anti-RT was developed in qualitative and quantitative forms, both were highly specific (lOO%, O/859; 99.6%, 3/859), the former was sensitive (loo%, 364/364) detecting the highest dilution of a standard high titre anti-HIV-l RT antibody positive control serum. The latter was less sensitive (97.2%, 354/364) detecting lower dilutions of the antibody control, but had the advantage of producing highly reproducible optical density/concentration curves for the quantification of unknown anti-RT samples. In a cross-sectional study of 191 patients with HIV-l infection, all patients developed anti-RT antibodies in CDC disease group II and III that declined but persisted in all cases into CDC disease group IV. The RT antigen assay was specific (loo%, O/772) and sensitive detecting 6 to 15 pg/ml of recombinant RT antigen diluted in normal human serum. No cross-reactivity using the RT antibody and antigen assays was seen in sera from 85 patients with current or previous hepatitis B infection or 21 sera from patients with HIV-2 infection. Further, no reactivity was demonstrated with the assays in a cohort of 20 seronegative partners (320 samples) exposed to HIV-l infection over a 4-yr period. In samples from a patient with documented seroconversion, RT antigen was the first detectable marker of HIV-l infection and was followed by a prompt anti-RT response. Serum RT antigen disappeared or remained low in most patients during CDC disease group II Correspondence to: C. Loveday, Division of Virology, University College and Middlesex School of Medicine, Windeyer Building, 46 Cleveland Street, London WIP 6DB, UK.