Emergence of a natural reassortant between Shamonda and Sathuperi viruses of the species Orthobunyavirus schmallenbergense in Japan.

The whole-genome sequences of orthobunyaviruses isolated from cattle reared on Yonaguni Island (the western-most point of Japan's territory) were determined. The sequences of their S and L RNA segments were observed to be almost identical to those of Shamonda virus (SHAV) isolates identified in Japan, whereas the sequences of their M RNA segments were very similar to those of Japanese isolates of Sathuperi virus (SATV). Our findings indicate that the two novel isolates are natural reassortants between SHAV and SATV, which share a genome segment organization similar to that of Schmallenberg virus. The nucleotide sequence of the 5' non-coding region of the novel isolates differs from those of previously sequenced SATV isolates, suggesting that the M RNA segments of the reassortants were not derived from SATV strains that were detected recently in Japan.