6th International AIDS Conference San Francisco, California, USA — June 20-23, 1990

Int Conf AIDS 1990 Jun 20-23; 6:320 (abstract no. 1027)
Gilbert M, Kirihara J, Mills J; University of California, San Francisco, California, USA

OBJECTIVES: A test that can measure gp120 concentration would be useful in laboratory and clinical studies with HIV.

METHODS: Recombinant, soluble CD4 (rsCD4) immobilized in microtiter trays was used to capture gp120, which was then detected with a three-layer detector-amplification system consisting of polyclonal sheep anti-gp120, biotinylated rabbit anti-sheep IgG, and avidin-alkaline phosphatase. Samples were incubated with p-nitrophenyl-phosphate and absorbance read at three and thirty-three minutes.

RESULTS: The assay showed a linear relationship between optical density and reference gp120 (recombinant, full-length, glycosylated gp120) concentration from 60 to 6000 pg/ml; the precision of the assay varied with the sample size, and ranging from +/- 50% with concentrations below 200 pg, to +/- 10% at concentrations above 200 pg/ml. In a group of replicate coded samples containing 60 pg/ml (approximately 10(7) molecules of gp120), the assay correctly identified the samples as containing gp120 90% of the time, with no false positives recorded in blank samples. Recombinant gp120 prepared in another cell culture system showed a binding coefficient which was 13-fold less than the reference gp120. With the assay system we were able to detect gp120 in HIV-1 suspensions prepared from cultured lymphoblastoid cells, and in the sera of HIV-1 infected patients.

CONCLUSIONS: This gp120 ELISA should be useful for studying the biology of gp-120 in HIV-1 infection.

900620
1027

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