Penggunaan antigen p24, IDR-Gp41 dan ID2-Pol dalam uji aviditas untuk identifikasi kasus baru pada infeksi HIV-1

Abstract

AIDS is a severe immunodeficiency disease caused by HIV. Identification of new HIV infection in a population is required for the evaluation of intervention strategy of HIV-1 transmission. The avidity assay has been promoted for HIV-1 detection. Avidity assay is based on affinity strength of the epitopes of the HIV antigen against its specific corresponding antibodies. The binding of the antigen the antibody formed in the initial phase of infection is relatively weak and easy to break with chaotropic reagents. In contrary, the antigenantibody binding formation in long-term infection is strong and not easily broken by addition of chaotropic reagents. Commercial avidity assays are available, however the antigens used might not be compatible with the circulating HIV strains in Indonesia. This research aimed to identify the most appropriate antigen candidate for avidity assay, three structural proteins from HIV were used i.e., p24, IDR-gp41 and ID2-Pol employed from the HIV strains circulating in Indonesia. The avidity assay was performed based on ELISA with pH 3 sodium citrate as chaotropic reagent. Serum samples was previously determined as positive and negative reactive by the Indonesian Red Cross. Each sample was tested in triplicates. The results of the avidity index were compared with the corresponding pattern of reactivity shown by Western Blotting. Comparative analysis of the avidity index using the IDR-Gp41 antigen showed correlation with increased value of avidity index with the completeness of the Western Blot reactivity pattern. This finding is not true in antigen ID2-Pol, and p24. Based on the results of the study, it can be concluded that IDR-Gp41 antigen has potential to be used in HIV avidity assay that is based on circulating strains of HIV in Indonesia.