The viruses were isolated from the blood of sentinel cattle and Culicoides biting midges in the Kyushu district, southwestern Japan, in 1999 and identified by neutralization tests as Peaton (PEA) viruses. Before this study, PEA virus had been isolated in Australia only. The nucleotide identity of the nucleocapsid (N) protein encoded by the S segment ranged from 91.1 to 91.6% between the Australian and Japanese strains. A phylogenetic analysis of the N protein sequence revealed that the PEA virus strains are closely related to Aino (AIN) virus and suggested reassortment events for PEA and AIN viruses.

The Japanese isolates of Palyam serogroup viruses isolated from 1985 to 2001 were investigated for the genome sequence of segments 2 and 7 and were phylogenetically analyzed in comparison with Australian and African isolates of the same serogroup. The nucleotide sequences of segment 7 were highly conserved within Japanese isolates (95.1 to 100%) and between Japanese and Taiwanese isolates (96.0 to 100%), whereas the identities between Japanese and Taiwanese isolates and Australian and African isolates were fairly conserved (84.2 to 92.0%). Phylogenetic analysis based on segment 7 revealed three clusters according to geographical origin. As a result of the nucleotide sequence analysis of segment 2, which encodes a serotype-specific antigen, Japanese isolates were classified into two groups by genome length and nucleotide identities. Four of the nine Japanese isolates were categorized into the same group as prototype strain K