Comparative Evaluation of HIV p24 Antigen assay and HIV Antigen-Antibody combination assay used in Thailand

Two types of HIV Test-kits, commercially available in Thailand, were evaluated for sensitivity to detect HIV-1 Infection. Seven and four products of Type 1 test-kit, a HIV Antigen-Antibody combination assay, and Type 2 test-kit, a HIV p24 antigen assay, were included in the study, respectively. The sensitivity tests were performed using 2 groups of samples. Group 1 was the 1st International Reference Reagent, HIV-1 p24 antigen (90/636) at concentrations of 60, 125, 250 and 500 mIU/ml. Group 2 was Seroconversion panels, containing 80 samples of serum from 9 HIV-infected individuals. Our results demonstrated that, using Group 1 sample, 2 and 4 products of Type 1 and Type 2 test-kits could, respectively, detect HIV p24 antigen at concentrations of 60 mIU/ml with a detection rate of 95%, while the rest of type 1 test-kit could detect the p24 antigen at concentrations ranging from 125-500 mIU/ml. The numbers of Group 2 samples detected by Type 1 and Type 2 test-kits were 23 - 36 and 34 - 37 samples, respectively. Our findings indicated that only 2 products of Type 1 test-kit had comparable sensitivity for antigen detection with the products of Type 2 test-kit. Key words : HIV p24 Antigen assay, HIV Antigen-Antibody combination assay, HIV Test-Kit Evaluation