Comparison of five ELISA assays for IgG antibody against coxsackievirus B1

Enterovirus type and group specificities of five different IgG ELISA methods were compared, using neutralization titration tests as an indicator of the presence or absence of antibodies to coxsackie B (CB) viruses. One of the ELISA assays was a "standard" IgG assay, where the solid phase was coated directly with the purified virus, followed by incubations with human serum, biotinylated anti-human-IgG, streptavidin-peroxidase, and the substrate/chromogen. In a modified standard assay, blocking of common epitopes was attempted by incubating the CB1 virus antigen on the solid phase with a rabbit antiserum to CB5 before the human serum was added. In another modification the serum dilution buffer contained heat-denatured heterologous enteroviruses in an attempt to consume human antibodies reacting with common epitopes. In one assay the purified CB1 virus was captured by purified horse anti-CB1 IgG on the solid phase, before incubation with human serum. In the last of the five assays the serum specimen was incubated with CB1 virus (in the liquid phase) before the virus or virus-antibody complex was captured with purified horse anti-CB1-IgG. Reactions against common antigens dominated in the first three assays. The antigen-capture assay appeared to be at least predominantly type specific. Our data indicate that the liquid-phase assay may be type specific, but more studies are needed. The method of virus purification was critical for the type specificity of the antigen-capture and liquid-phase assays.