Pathogenicity and genetic characterisation of a novel reassortant, highly pathogenic avian influenza (HPAI) H5N6 virus isolated in Korea, 2017

Abstract

We investigated influenza A(H5N6) viruses from migratory birds in Chungnam and Gyeonggi Provinces, South Korea following a reported die-off of poultry in nearby provinces in November 2017. Genetic analysis and virulence studies in chickens and ducks identified our isolate from December 2017 as a novel highly pathogenic avian influenza virus. It resulted from reassortment between the highly virulent H5N8 strain from Korea with the N6 gene from a low-pathogenic H3N6 virus from the Netherlands.

Novel H5N6 avian influenza virus reassortants with European H5N8 isolated in migratory birds, China

“…Clade 2.3.4.4B H5N6 viruses were detected in the Netherlands, South Korea and China in 2017–2018. The H5N6 virus detected in the Netherlands was a reassortant of H5N8 Clade 2.3.4.4B viruses that obtained novel PB2 and NA segments derived from Eurasian LPAIVs (Beerens, ), and the viruses isolated in South Korea were obtained from a reassortment that occurred between Clade 2.3.4.4B H5N8 viruses and Eurasian LPAIVs circulating in wild birds (Kim, ). The virus isolated in China was a reassortant of Clade 2.3.4.4B H5N8 viruses with novel NA segments derived from Asian LPAIVs and was genetically similar to H5N6 HPAIVs identified from Japan (Liu, ).…”

“…Based on the phylogenetic analysis of the PB2 and M genes, the novel H5N6 HPAIVs grouped into Clade 2.3.4.4B and belonged to three clusters designated Cluster I, Cluster II and Cluster III. The novel H5N6 HPAIVs were successively isolated from domestic poultry and wild birds in Japan, China (Cluster I), the Netherlands (Cluster I and III), Korea, Germany and England (Cluster I) during the 2017–2018 winter (Beerens, ; Kim, ; Liu, ). In addition to the H5N6 HPAIVs, one H5N6 LPAIV, which was also detected in Ningxia, China, was a reassortant influenza virus carrying the HA and NA gene segments originating from LPAIVs and all six internal gene segments from H5N8 HPAIVs and is classified as Cluster IV.…”

“…Two viruses can replicate in the lung and nasal turbinate, and the capacity of replication in the lung was stronger than that in the other organs. Survival percentage of (b) SBD-87 and (c) SBD-83 was calculated by observing infected mice [Colour figure can be viewed at wileyonlinelibrary.com] wild birds in Japan, China (Cluster I), the Netherlands (Cluster I and III), Korea, Germany and England (Cluster I) during the 2017-2018 winter (Beerens, 2018;Kim, 2018;Liu, 2018). In addition to the H5N6 HPAIVs, one H5N6 LPAIV, which was also detected in Ningxia, China, was a reassortant influenza virus carrying the HA and NA gene segments originating from LPAIVs and all six internal gene segments from H5N8 HPAIVs and is classified as Cluster IV.…”

Avian influenza overview November 2017 ‐ February 2018

“…DetectionsBesides the novel zoonotic reassortant HPAI A(H5N6) belonging to clade 2.3.4.4c, which was detected in domestic and wild birds in China, Japan, Myanmar, the Philippines, the Republic of South Korea, Taiwan and Vietnam since 2016, another novel reassortant HPAI A(H5N6) closely associated to clade 2.3.4.4b mainly circulating in Eurasia was isolated in December 2017 in Chungnam and Gyeonggi province from faecal samples of mallards (Anas platyrhynchos)(Kim et al, 2018). In the relevant time period for this report the Republic of South Korea confirmed 25 outbreaks of A(H5N6) HPAIV in large poultry and duck farms until February 2018, but no new cases of the zoonotic reassortant of HPAI A(H5N6) (2.3.4.4c) were reported from China.…”

Novel Highly Pathogenic Avian Influenza A(H5N6) Viruses in the Netherlands

“…H5N6 subtype viruses have been identified in multiple Eurasian regions and have shown diverse genotypes since the beginning of 2017. Clade 2.3.4.4 group B H5N6 subtype viruses were reported to have affected migratory birds and poultry in South Korea in December 2017 ( 2 ). The viruses from South Korea have PB2 and polymerase acidic genes distinct from those of viruses from the Netherlands.…”