Abstract Title
Continuous invasion of clade 2.3.4.4b H5N1 high pathogenicity avian influenza virus in an urban garden in Hokkaido, Japan, between 2022-2024
Abstract
[Objectives] Continuous introductions of clade 2.3.4.4b H5 high pathogenicity avian influenza (HPAIVs) were confirmed in Hokkaido, the northern part of Japan, every winter since 2022. Following to HPAIV introduction by bird migration, HPAIV infections in crows were confirmed in an urban garden in Sapporo, the capital city of Hokkaido. H5 HPAIVs isolated from crows in the garden were phylogenetically analyzed, and the epidemiology of HPAIV infection in crows was investigated.
[Materials and methods] Eighty-six, 47, and 82 crow carcasses probably due to HPAIV infection were reported in the spring of 2022, 2023, and 2024, respectively. After virus isolation from crows, full genome sequences were obtained to perform the phylogenetic analysis. Susceptivity to HPAIV in crows was assessed by virus recovery from the carcasses and sialoside distribution on the epithelial cells of crow organs. The case reproduction numbers (Rcs) of HPAIV-positive crows in each year were calculated to assume the HPAIV dynamics in the crow flock.
[Results and discussions] From the crows, H5N1 and H5N5 subtypes of HPAIVs were isolated. Recovery of HPAIV with high titers in the lungs, brain, and rectal contents of crows could support the wide distribution of α2-3 sialosides binding to the H5 HA of an HPAIV isolate in the garden. Nevertheless, the results of phylodynamic analysis and Rcs could conclude multiple introductions of HPAIVs into the crow flock rather than widespread internal transmission of HPAIVs in the crow flock. Further investigations about HPAIV ecology in crows at individual and flock levels will be required.
[Materials and methods] Eighty-six, 47, and 82 crow carcasses probably due to HPAIV infection were reported in the spring of 2022, 2023, and 2024, respectively. After virus isolation from crows, full genome sequences were obtained to perform the phylogenetic analysis. Susceptivity to HPAIV in crows was assessed by virus recovery from the carcasses and sialoside distribution on the epithelial cells of crow organs. The case reproduction numbers (Rcs) of HPAIV-positive crows in each year were calculated to assume the HPAIV dynamics in the crow flock.
[Results and discussions] From the crows, H5N1 and H5N5 subtypes of HPAIVs were isolated. Recovery of HPAIV with high titers in the lungs, brain, and rectal contents of crows could support the wide distribution of α2-3 sialosides binding to the H5 HA of an HPAIV isolate in the garden. Nevertheless, the results of phylodynamic analysis and Rcs could conclude multiple introductions of HPAIVs into the crow flock rather than widespread internal transmission of HPAIVs in the crow flock. Further investigations about HPAIV ecology in crows at individual and flock levels will be required.
Co-Author(s)
Norikazu Isoda1,2,3,4, Takahiro Hiono1,2,3,4, Fumihito Takaya5, Yik Lim Hew1, Tatsuru Morita1, Nguyen Bao Linh1, Daiki Kobayashi1, Yoshihiro Sakoda1,2,3,4
1Laboratory of Microbiology, Faculty of Veterinary Medicine, Hokkaido University, Japan
2One Health Research Center, Hokkaido University, Japan
3International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Japan
4Hokkaido University Institute for Vaccine Research and Development (HU-IVReD), Hokkaido University, Japan
5Botanic Garden, Field Science Center for Northern Biosphere (FSC), Hokkaido University, Japan
Abstract Category
Notable outbreaks, field and molecular epidemiology, and surveillance in wild birds