Detection of antibodies to the HIV-1 p25/24 and gp120 proteins by sphere-linked immunodiagnostic assay (SLIDA).

In this paper, we have used the technique known as sphere-linked immunodiagnostic assay (SLIDA) for the detection of antibodies to HIV-1 p25/24 and gp120 proteins. In this technique, the p25/24 and gp120 proteins were covalently bonded to 0.5 micron carboxylated microspheres. They were then exposed to serial dilutions of rabbit antiserum to HIV-1 p25/24, sheep antiserum to gp120 and dilutions of the corresponding normal sera. Specific immunolabeling was monitored by using gold-labeled secondary antibody. The gold particles bound to the microspheres were an indication for the presence of specific antibody in the serum sample. The gold-labeled microspheres were photographed using a transmission electron microscope, and the number of gold particles bound to the microspheres were counted manually using the electron micrographs. The specificity and sensitivity of the technique were then compared to enzyme-linked immunosorbent assay (ELISA) and Western blotting.