Abstract
Since 2014, H5Nx high pathogenicity avian influenza (HPAI) belong to clade 2.3.4.4 caused outbreaks around world. During the 2022–2023 winter season in South Korea, novel clade 2.3.4.4b H5N1 HPAI viruses were first detected in wild birds and subsequently caused multiple outbreaks on poultry farms and in wild birds. Here, we examined the genetic characteristics of H5N1 HPAI viruses isolated in 2022–2023, and its pathogenicity and transmissibility in chickens and ducks. Phylogenetic analysis of HA genes showed that the Korean H5N1 HPAI isolates were closely related to Eurasian and American HPAI viruses isolated in 2022–2023. Twenty-one distinct genotypes (22G0–22G20) were identified from Korean HPAI virus isolates by gene constellation analysis; among these, the 22G7 was dominant genotype. The 22G1 genotype (A/duck/Korea/H493/2022(H5N1)) caused virulent pathogenicity, with 100% mortality in SPF chickens. Ducks inoculated with genotypes 22G1 or 22G7 (A/duck/Korea/H537/2022(H5N1)) showed neurological signs and 60-80% of mortality. In the contact groups of both chicken and ducks, 100% of transmissibility were observed. Moreover, 22G7 inoculated ducks showed longer viral shedding via the cloacal route, and virus replication in cecal tonsil was higher than those of 22G1 group, which may be one of the reasons for 22G7 became the dominant genotype. Therefore, it is important to understand the genetic and pathogenic characteristics of HPAI viruses for effective virus control in the field.
Co-Author(s)
Ra Mi Cha, Min-Ji Park, Yunyoung Jang, Gyeong-Beom Heo, Se-Hee An, Kwang-Nyeong Lee, Youn-Jeong Lee, and Eun-Kyoung Lee
Avian Influenza Research & Diagnostic Division, Animal and Plant Quarantine Agency
177,Hyeoksin 8-ro, Gimcheon-si, Gyeongsangbuk-do, 39660, Republic of Korea
Abstract Category
Notable outbreaks, field and molecular epidemiology, and surveillance in poultry