Relative frequency of human rotavirus subgroups 1 and 2 in Japanese children with acute gastroenteritis.

Recently developed monoclonal antibodies against the 42,000-dalton major inner capsid protein were used in an enzyme immunoassay to subgroup a total of 156 rotavirus specimens obtained from Japanese infants and young children with acute gastroenteritis during the period between December 1981 and April 1983. Only 2 specimens (1.3%) were identified as subgroup 1, whereas 154 specimens (98.7%) were identified as subgroup 2. The percentage of subgroup 2 rotaviruses obtained in this study was the highest among similar studies thus far performed in different areas of the world. One of the subgroup 1 isolates had fast-moving 10th and 11th gene segments (the "long" pattern) typical of the subgroup 2 human rotaviruses.