How Do Rapid HIV tests work?

Multiple epitope fusion HIV-1 and HIV-2 proteins are bound to the membrane of the filtration device. When antibodies to HIV-1 and HIV-2 are present in the test serum, they react with the recombinant proteins and attach to the solid-phase. Non-reactive antibodies are filtered through with the wash buffer. Human IgGs bound on the membrane are visualized by reacting with colloidal gold Protein A. The appearance of TWO RED DOTS ( one corresponding to the procedural control and one to the recombinant HIV 1 and 2 proteins) indicates a positive reaction. The appearance of a single red dot corresponding to procedural control indicates a negative reaction.