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Ten hybridomas secreting monoclonal antibodies (Mab) against recombinant HIV-1 and HIV-2 antigens were produced (3 Mab anti-gag protein, 2 anti-env1, and 5 anti-env2). In the immunoblotting assay all the anti-gag Mabs reacted with HIV capsid protein p24, whereas one of them reacted also with p55 protein and with 7 other polypeptides. Another anti-gag Mab cross-reacted with the antigen of subpopulation of human peripheral blood lymphocytes. The third one interacted with the antigen of both HIV-1 and HIV-2. All the 10 Mabs interacted with natural HIV antigens and can be used for identification and differentiation of HIV-1 and HIV-2.

A test system using monoclonal antibodies to HIV p24 was developed for solid-phase ELISA for detection of HIV antigen (AG) which helped detect the content of AG in samples with trace concentrations, less than 25 pg/ml. The test system can be used for AG monitoring in natural specimens (serum of HIV-infected patients and culture medium of infected cells) and for determination of antigen-recombinant product of HIV gag gene.

Three modifications of ELISA test system for HIV antigen detection are described. They are based on IgG from HIV-1 and HIV-2-infected human sera and monoclonal antibodies against HIV-1 p24 used as immunosorbents. The peroxidase/anti-HIV-IgG conjugate was used in all the test systems. A possibility of quantitative detection of viral antigen in native culture fluids, lysates, and purified virus preparations was demonstrated. The test system for HIV-1 antigen detection cannot be used for HIV-2 antigen detection and vice versa. The diagnostic value of HIV-1 p24 antigen detection consists in the possibility of earlier AIDS identification and monitoring of the disease at various stages. The sensitivity of "p24" assay is 0.5 ng/ml.

Using a panel of sera from HIV-infected persons and donors, the authors showed that radioimmunoprecipitation assays compare favourably with immunoblotting assays. With radioimmunoprecipitation, cross reactions were observed between HIV-2 antigens and HIV-2 antibodies, and that the nature of cross reactivity differs from that observed with immunoblotting. Potentials of radioimmunoprecipitation assays as a confirmatory test for use with sera that have given indeterminate results in immunoblotting assays and contradictory results in enzyme immunoassays are examined.

The results of the development and trials of two variants of EIA test system for the detection of HIV-1 antigen using biotinated HIV-antibody and streptavidin-peroxidase or biotin-beta-lactamase enzyme complexes are presented. These diagnostic preparations proved to be highly sensitive and specific allowing the detection of the antigen in the blood of HIV-infected subjects.

Cells from anti-HIV-positive persons were used in experiments for virus isolation. The RT-activity, viral antigen, nucleic acids, electron microscopic morphology, and infectivity were studied. The data presented allow a conclusion that the virus was isolated. These data confirmed the previous diagnosis of HIV infection.