Molecular epidemiological analyses of the teratogenic Aino virus based on the sequences of a small RNA segment

The sequences of a small RNA segment of Aino virus isolates were analyzed to define the molecular epidemiology and genetic relationships to other species in the genus Orthobunyavirus in the family Bunyaviridae. The nucleotide and amino acid sequences of the segment were highly conserved among strains isolated from 1964 to 2002 in Japan. These Japanese isolates were segregated into two distinct lineages, one containing the prototype strain JaNAr28 isolated in 1964 and the other containing strains isolated after 1986, by phylogenetic analysis based on the nucleocapsid gene sequences. Japanese strains isolated after 1986 were rather more closely related to Kaikalur virus isolated in India in 1971 than to strain JaNAr28. On the other hand, an Australian strain, B7974, was closely related to Peaton virus. The B7974 strain might have been generated by inter-serotype genetic reassortment between Aino and Peaton viruses in Australia during their evolution. However, recent Aino virus strains isolated in Japan appear to be genetically stable.