Abstract
During 2014–2016 HPAI outbreak in South Korea, H5N8 viruses have been mostly isolated in western areas of the country, which provide wintering habitats for wild birds and have a high density of poultry. Analysis of a total of 101 Korean isolates revealed that primitive H5N8 viruses (C0 group) have evolved into multiple genetic subgroups appearing from various epidemiological sources, namely, the viruses circulating in poultry farms (C1 and C5) and those reintroduced by migratory birds in late 2014 (C2 and C4). No C3 groups were detected. The results may explain the possible reasons of the recent long-term persistence of H5N8 viruses in South Korea, and help to develop the effective measures in controlling HPAI viruses.