Serological evidence of H5-subtype influenza A virus infection in indigenous avian and mammalian species in Korea

In Korea, H5-subtype highly pathogenic avian influenza (HPAI) has caused huge economic losses in poultry farms through outbreaks of H5N1 since 2003, H5N8 since 2013 and H5N6 since 2016. Although it was reported that long-distance migratory birds may play a major role in the global spread of avian influenza viruses (AIVs), transmission from such birds to poultry has not been confirmed. Intermediate hosts in the wild also may be a potential factor in viral transmission. Therefore, a total of 367 serum samples from wild animals were collected near major migratory bird habitats from 2011 to 2016 and tested by AIV-specific blocking ELISA and hemagglutination inhibition (HI) test. Two mammalian and eight avian species were seropositive according to the ELISA test. Among these, two mammalian (Hydropotes inermis and Prionailurus bengalensis) and three avian (Aegypius monachus, Cygnus cygnus, and Bubo bubo) species showed high HI titres (> 1,280) against one or two H5-subtype AIVs. As H. inermis (water deer), P. bengalensis (leopard cat), and B. bubo (Eurasian eagle owl) are indigenous animals in Korea, evidence of H5-subtype AIV in these animals implies that continuous monitoring of indigenous animals should be followed to understand interspecies transmission ecology of H5-subtype influenza viruses.