Genetic characterization of Aino and Peaton virus field isolates reveals a genetic reassortment between these viruses in nature.

Sequence determination and phylogenetic analysis were conducted using the S, M and L RNA segments of the 10 Aino, 6 Peaton and 1 Sango virus (AINOV, PEAV and SANV) field isolates of the genus Orthobunyavirus in the family Bunyaviridae, respectively. The Japanese AINOV strains were genetically stable, but the sequence differences between the Japanese and Australian AINOV strains were considerably larger than those among the Japanese AINOV strains. A similar result was found in the genetic relationship among Japanese and Australian PEAVs, and SANV which was isolated in Nigeria and was thought as a synonym of PEAV, suggesting that geographic separation contributed significantly to the evolution of those viruses. The Australian AINOV strain B7974 is more closely related to the Australian PEAV strain CSIRO110 than to the Japanese AINOV strains in the S and L RNA segments, while the phylogenetic position of the M RNA segment of the B7974 strain was clustered with those of the Japanese AINOV strains. Our findings indicate that the B7974 strain is a reassortment with the M RNA segment derived from AINOV and the S and L RNA segments derived from an Australian PEAV.