Use of enzyme-linked immunosorbent assay for the determination of serological relationship between two comoviruses.

ELISA was used to determine the degree of serological relationship between red clover mottle (RCMV) and broad bean stain (BBSV) viruses and the optimal conditions for the differentiation of the two viruses by ELISA were established. The titres of homologous and heterologous antibodies determined by ELISA were 100- to 200-fold higher as compared with the ring precipitin test. Antigen concentrations of 0.15 and 0.075 ng/ml, respectively, could be detected. The reactions in ELISA depended on the concentration of antigen, of IgG used for coating and of conjugated IgG. In anti-RCMV IgG, the ratio of group-specific to species-specific antibody as determined by ELISA was from 1:1 to 1:2, while in anti-BBSV IgG this ratio was from 1:4--1:8. The differences between homologous and heterologous reactions in ELISA suggested a similar ratio of antigenic determinants in the two viruses.