Antibody survey for Inoue-Melnick virus infections in Osaka and Houston.

: Neutralizing antibodies to the Inoue-Melnick virus were detected in healthy adults in Osaka and in Houston. For adults, the prevalence rate for the cross-reacting type 3 virus was 13.8 per cent in Osaka and 29.1 per cent in Houston. Antibodies were also found in immune serum globulin prepared from American adults, but not in sera of Osaka children under 10 years of age. The Inoue-Melnick virus isolates so far obtained in Houston could be classified into three antigenic types, but in Japan all have been type 1. Type 3 antibody tests detect all homotypic infections plus about 82 per cent of type 1 infections. Thus, the actual prevalence rates for type 1 infections in Japan are somewhat higher than those found with the type 3 assay, namely, about 14 per cent for young adults and 24 per cent for those over 50 years of age. Further studies are needed to elucidate the natural history of this virus infection.