Surveillance of whooper swan migration is important for monitoring avian
influenza transmission risk potential from east to west China between
the East Asian--Australasian and Central Asian flyways. Here, we
characterised the evolutionary and reasssortment history of H5N2 viruses
isolated from 1866 fresh faeces samples of wintering whooper swans
collected in the Sanmenxia Reservoir area, China. This was combined with
information on the migration routes of whooper swans in Eastern Asia to
elucidate the role of whooper swans in spreading the virus. All segments
of the new H5N2 isolates belong to the Eurasian avian-like lineage and
are closely related to wild-bird viruses from China, Korea and Mongolia
covering the wintering, stopover and breeding grounds in migration
routes of whooper swans. We further found that the temporal-spatial
migration process of whooper swans was identical with the virus
transmission and reassortment pathway in Eastern Asia particularly.