Immunoglobulin A and G reactivities to human reovirus were investigated comparatively by Western blot and ELISA in a collection of 120 serum samples. Five different reovirus polypeptides of molecular weights of 127, 79, 54 42 and 40 kDa were visualized by polyacrylamide gel electrophoresis. Of 80 anti-reovirus ELISA-IgG positive serum samples, 97.5% and 15.0% reacted with one or more virus-specific bands in the IgG and IgA Western blot respectively. The 127 and 79 kDa proteins reacted with 100% and 96.2% of the IgG Western blot-positive serum samples (n = 78). IgG reactivities to the 40, 54 and 42 kDa proteins were detected in 96.2%, 80.8% and 20.5% of the immunoblot-positive sera. Compared to the Western blot, the ELISA had a specificity of 94.9% for IgG and 96.3% for IgA detection. The sensitivity of specific IgG and IgA detection by ELISA were 96.3% and 100%, respectively. Using the ELISA, a seroepidemiological survey was carried out on 850 sera collected from October 1989 to September 1992. The overall prevalence of reovirus IgG and IgA antibodies were 53.5% and 15.5% respectively. An age dependent increase of the seroprevalence of anti-reovirus IgG was observed. In contrast, the prevalence of IgA antibodies remained constant during childhood. Seroprevalence peak levels were observed in the 9-11, 20-29, 40-49 and > or = 60 years age group. The results of the study suggest that antireovirus IgG antibodies may persist lifelong, whereas IgA antibodies are detectable for a short time and may indicate a recent reovirus infection. The development of a sensitive and specific ELISA assay for the detection of class-specific immunoglobulins permits further investigation of reovirus infections and may contribute to improving the serological diagnosis of recent infection.