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The purpose of the present investigation was to comparatively evaluate the performance characteristics of the test systems designed to verify the positive results of screening survey for HIV infection, such as the solid-phase immunoassay DS-EIA-HIV-AB/AG-SPECTR (Diagnosticheskiye Sistemy (Diagnostic Systems) Research-and-Production Association, Nizhni Novgorod) and tests based on immune blotting (IB). The investigation examined 15 seroconversion panels produced by ZeptoMetrix (USA) and BBI (USA). The use of the DS-EIA-HIV-AB/AG-SPECTR test system determined 88 of the 167 seroconversion panels as HIV positive. The IB-based tests revealed only 45 of the 167 samples as positive. Consequently, the application of the DS-EIA-HIV-AB/AG-SPECTR test system is more effective than the IB-based tests in early HIV infection.

Aim: To evaluate diagnostic value of p24 antigen detection for algorithm of confirmatory diagnostics of HIV-infection., Materials and Methods: Concurrently with Western blot assay (WB, "New Lav Blot1", Bio-Rad), tests for detection of p24 antigen of HIV (Genetic Systems HIV-1 Ag EIA", "VectoHIV-1 p24-antigen confirming test", and "DS-EIA-HIV-AG-SCREEN") were used for confirmation of first-positive result of immuno-enzyme assay., Results: p24 HIV antigen was detected in serum samples in 8.4% of patients with equivocal result of WB and in 4.2% of patients with negative and positive results of WB. Presence of p24 was correlated with high viral load, and, in patients with confirmed diagnosis, with low CD4 cells count (<500 cells/ml). p24 was detected in more than 30% of persons with confirmed seroconversion after primary testing., Conclusion: In groups of persons with negative and equivocal results of WB assay, detection of HIV p24 antigen points to the presence of infection and could be the reason for the final diagnosis. Detection of p24 in patients with positive result of WB assay allows to consider them as probable candidates for highly active antiretroviral therapy.

A "DS-EIA-HIV-AG-Screen" enzyme immunoassay system has been devised to detect HIV-1 p24 antigen with a sensitivity of 0.5 pg/ml the use of which permits reduction of a seronegative window phase as compared with the tests showing a lower sensitivity threshold. The "DS-EIA-HIV-AG-Screen" system developed may be used to screen donor blood and to examine risk-group individuals for the early diagnosis of HIV infection.

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.