Apparent re-emergence of serotype G9 in 1995 among rotaviruses recovered from Japanese children hospitalized with acute gastroenteritis

Serotype G9 rotaviruses have been detected in about 0.5% of the circulating strains worldwide. However, G9 strains emerged globally in the middle of t he 90s and thereafter. A rotavirus, contained in stool specimen 95H11.5, po ssessing a G9 VP7 emerged in Japan in the 1994-1995 season for the first ti me after a 9-year interval since prototype G9 strains AU32 and F45 were dis covered in the 1985-1986 season. In comparison with other G9 VP7 genes thus far published, the sequencing of the VP7 genes of AU32 and 95H115 revealed that the 95H115 VP7 gene did not directly evolve from the AU32 VP7 gene bu t was much more closely related to the contemporary G9 VP7 genes found in t he United States of America. Thus, recently emerging G9 VP7 genes were not direct descendants of the VP7 genes of the prototype strains in the 80s, ra ther they evolved independently into 4 phylogenetic clusters from a common ancestor.