Determination of Antibodies to Double-Stranded RNA by Enzyme-Linked Immunosorbent Assay (ELISA)

Abstract

A sensitive enzyme-linked immunosorbent assay (ELISA) for antibodies to double-stranded RNA has been developed using polyinosinic acid . polycytidylic acid (I _n C _n ) as antigen. Bound antibody was detected using alkaline phosphatase-conjugated goat antiimmunoglobulin and ρ-nitrophenylphosphate as substrate. The assay, as demonstrated for rabbit, NZB/NZW mouse, and grivet monkey sera, was far more sensitive and reproducible than quantitative complement fixation. I _n C _n complexed with poly-L-lysine and adsorbed to polystyrene tubes resulted in optimal uptake of antibodies to double-stranded RNA. I _n -C _n without added poly-L-lysine or with other cationic substances adsorbed poorly, as measured by reduced antibody uptake. Specificity of the assay for antibodies to double-stranded RNA was demonstrated by reduction of antibody binding to antigen-coated tubes following adsorption of sera with double-stranded, but not single-stranded RNAs. Similar adsorption studies indicated that this method could be used also to assay for double-stranded RNA. Therefore, a simple ELISA can be used for quantitative determination of either antibodies to double-stranded RNA or double-stranded RNA antigen.