Reassortant Clade 2.3.4.4 Avian Influenza A(H5N6) Virus in a Wild Mandarin Duck, South Korea, 2016

The wide geographic spread of Eurasian Goose/Guangdong lineage highly pathogenic avian influenza (HPAI) clade 2.3.4.4 viruses by wild birds is of great concern. In December 2014, an H5N8 HPAI clade 2.3.4.4 Group A (2.3.4.4A) virus was introduced to North America. Long-distance migratory wild aquatic birds between East Asia and North America, such as Northern Pintail (Anas acuta), were strongly suspected of being a source of intercontinental transmission. In this study, we evaluated the pathogenicity, infectivity and transmissibility of an H5N8 HPAI clade 2.3.4.4A virus in Northern Pintails and compared the results to that of an H5N1 HPAI clade 2.3.2.1 virus. All of Northern Pintails infected with either H5N1 or H5N8 virus lacked clinical signs and mortality, but the H5N8 clade 2.3.4.4 virus was more efficient at replicating within and transmitting between Northern Pintails than the H5N1 clade 2.3.2.1 virus. The H5N8-infected birds shed high titre of viruses from oropharynx and cloaca, which in the field supported virus transmission and spread. This study highlights the role of wild waterfowl in the intercontinental spread of some HPAI viruses. Migratory aquatic birds should be carefully monitored for the early detection of H5 clade 2.3.4.4 and other HPAI viruses.

Section: Resultsmentioning

confidence: 99%

Experimental infection of H5N1 and H5N8 highly pathogenic avian influenza viruses in Northern Pintail (Anas acuta )

Kwon

Lee

Swayne

et al. 2018

“…Since 2003, a total of 7 Gs/GD‐like HPAIV outbreaks have reported in South Korea. Previous studies suggested that wild waterfowl played a major role in the spread of these HPAIV between China, South Korea and Japan (Kanehira et al, ; Kim et al, ; Kim et al, ; Kwon et al, ; Kwon et al, ; Lee et al, ; Mase et al, ; Sakoda et al, ; Uchida et al, ; Wee et al, ). Consistent with these findings, our phylogenetic analysis suggests that the outbreak in South Korea was initiated through multiple independent introductions with wild waterfowl origin clade 2.3.4.4A H5N8 HPAIV.…”

Section: Discussionmentioning

confidence: 99%

Domestic ducks play a major role in the maintenance and spread of H5N8 highly pathogenic avian influenza viruses in South Korea

Kwon

Bahl

Swayne

et al. 2019

Self Cite

The H5N8 highly pathogenic avian influenza viruses (HPAIVs) belonging to clade 2.3.4.4 spread from Eastern China to Korea in 2014 and caused outbreaks in domestic poultry until 2016. To understand how H5N8 HPAIVs spread at host species level in Korea during 2014–2016, a Bayesian phylogenetic analysis was used for ancestral state reconstruction and estimation of the host transition dynamics between wild waterfowl, domestic ducks and chickens. Our data support that H5N8 HPAIV most likely transmitted from wild waterfowl to domestic ducks, and then maintained in domestic ducks followed by dispersal of HPAIV from domestic ducks to chickens, suggesting domestic duck population plays a central role in the maintenance, amplification and spread of wild HPAIV to terrestrial poultry in Korea.

“…Complete genome analysis of the H5N6 HPAIVs isolated from poultry and wild birds in Japan between 2016 and 2017 demonstrated that 12 strains of the H5N6 HPAIVs isolated from poultry during this time could be classified according to their gene constellations into four groups (C1, C2, C4 and C6) by following the criteria established by Kwon et al. (Kwon et al., ). In addition, a single isolate from a mute swan in Kyoto, Japan belonged to another genotype (C5) (Takemae et al., ).…”

Section: Introductionmentioning

confidence: 99%

Comparative pathogenicity of H5N6 subtype highly pathogenic avian influenza viruses in chicken, Pekin duck and Muscovy duck

Uchida

Mine

Takemae

et al. 2019

Summary In Japan during the 2016–2017 winter season, clade 2.3.4.4 highly pathogenic avian influenza viruses (HPAIVs) of the H5N6 subtype caused 12 outbreaks in chicken and Muscovy duck farms. These viruses have been circulating in Vietnam and China since 2014. In this study, we evaluated the susceptibility of chicken, Pekin duck (Anas platyrhynchos domesticus) and Muscovy duck (Cairina moschata) to H5N6 HPAIVs that originated in Japan, Vietnam and China. The H5N6 HPAIVs examined in this study were highly lethal to chickens compared with their pathogenicity in Pekin duck and Muscovy duck. One of five chickens infected with A/Muscovy duck/Aomori/1‐3T/2016 (MusDk/Aomori) survived despite viral shedding, although all of the chickens infected with the other viruses died. The 50% chicken lethal dose differed among the Japanese strains that shared the same gene constellation indicating that gene constellation was not a major determinant of pathogenicity in chicken. MusDk/Aomori, A/chicken/Niigata/1‐1T/2016 (Ck/Niigata) and A/duck/Hyogo/1/2016 (Dk/Hyogo) infected all Muscovy ducks inoculated; Ck/Niigata killed 50% of the ducks it infected whereas the other two did not kill any ducks. A/chicken/Japan/AnimalQuarantine‐HE144/2016 (HE144) isolated from chicken meat that originated in China was highly pathogenic to Pekin duck: all of the ducks died within 3.75 days of inoculation. This study shows that the pathogenicity of the clade 2.3.4.4 H5N6 HPAIVs differs not only between hosts but also within the same host species.