Emergence of Novel Highly Pathogenic Avian Influenza Virus A(H5N1) Clade 2.3.4.4b in Commercial Poultry, Bangladesh
Abstract
Background The high‐pathogenicity avian influenza (HPAI) viruses represent a main threat to animal and human health, poultry productivity, and ecosystems. The newly evolved A(H5N1) clade 2.3.4.4b has become a worldwide concern for its expanding multihost ecology, including poultry and a wide range of mammalian species. Methods Avian influenza virus (AIV) was isolated from an outbreak in commercial quail farms associated with severe respiratory signs and high mortality. Molecular characterization of the detected virus was performed through gene sequencing via whole‐genome sequencing technology and phylogenetic analysis. Results Genetic and phylogenetic analyses revealed that the hemagglutinin (HA) gene clustered closely with a recent HPAI A(H5N1) clade 2.3.4.4b strain from live bird markets (LBMs) in Bangladesh, with a most recent common ancestor dated to July 2023. The NA gene and four internal genes (PB1, NP, MP, NS) were derived from contemporary A(H5N1) viruses of ducks in LBMs, while the PB2 and PA segments exhibited similarity to low pathogenicity avian influenza (LPAI) viruses, suggesting reassortment events within avian hosts. The presence of a multibasic cleavage site (PLREKRRKR↓GLF) with avian‐specific receptor‐binding residues (Q224 and G226) and five conserved glycosylation motifs, consistent with high‐pathogenicity phenotypes and strong avian receptor affinity. The PB2 gene harbored a rare I147T substitution; however, key mammalian adaptation markers such as E627K and D701N were absent. Conclusion The reassortant A(H5N1) clade 2.3.4.4b virus with high pathogenicity and genetic links to LBM‐origin strains is now circulating in the commercial poultry population in Bangladesh, increasing the risk of viral adaptation, the potential for cross‐species transmission, and threatening the poultry sector and public health.
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BibTeX
@article{samad2026emergence,
title = {{Emergence of Novel Highly Pathogenic Avian Influenza Virus A(H5N1) Clade 2.3.4.4b in Commercial Poultry, Bangladesh}},
author = {Mohammed A Samad and Md Rezaul Karim and Amelia Coggon and Anowar Hossen and A S M Ashab Uddin and Md Golbar Hossain and Guillaume Fournie and Nicola S Lewis and Alexander M P Byrne},
journal = {Influenza and Other Respiratory Viruses},
year = {2026},
month = sep,
doi = {10.1111/irv.70324},
url = {https://hal.inrae.fr/hal-05778205v1},
note = {CC BY-NC 4.0},
}
RIS
TY - JOUR
TI - Emergence of Novel Highly Pathogenic Avian Influenza Virus A(H5N1) Clade 2.3.4.4b in Commercial Poultry, Bangladesh
AU - Mohammed A Samad
AU - Md Rezaul Karim
AU - Amelia Coggon
AU - Anowar Hossen
AU - A S M Ashab Uddin
AU - Md Golbar Hossain
AU - Guillaume Fournie
AU - Nicola S Lewis
AU - Alexander M P Byrne
PY - 2026
DA - 2026/09/21
JO - Influenza and Other Respiratory Viruses
DO - 10.1111/irv.70324
UR - https://hal.inrae.fr/hal-05778205v1
AB - Background The high‐pathogenicity avian influenza (HPAI) viruses represent a main threat to animal and human health, poultry productivity, and ecosystems. The newly evolved A(H5N1) clade 2.3.4.4b has become a worldwide concern for its expanding multihost ecology, including poultry and a wide range of mammalian species. Methods Avian influenza virus (AIV) was isolated from an outbreak in commercial quail farms associated with severe respiratory signs and high mortality. Molecular characterization of the detected virus was performed through gene sequencing via whole‐genome sequencing technology and phylogenetic analysis. Results Genetic and phylogenetic analyses revealed that the hemagglutinin (HA) gene clustered closely with a recent HPAI A(H5N1) clade 2.3.4.4b strain from live bird markets (LBMs) in Bangladesh, with a most recent common ancestor dated to July 2023. The NA gene and four internal genes (PB1, NP, MP, NS) were derived from contemporary A(H5N1) viruses of ducks in LBMs, while the PB2 and PA segments exhibited similarity to low pathogenicity avian influenza (LPAI) viruses, suggesting reassortment events within avian hosts. The presence of a multibasic cleavage site (PLREKRRKR↓GLF) with avian‐specific receptor‐binding residues (Q224 and G226) and five conserved glycosylation motifs, consistent with high‐pathogenicity phenotypes and strong avian receptor affinity. The PB2 gene harbored a rare I147T substitution; however, key mammalian adaptation markers such as E627K and D701N were absent. Conclusion The reassortant A(H5N1) clade 2.3.4.4b virus with high pathogenicity and genetic links to LBM‐origin strains is now circulating in the commercial poultry population in Bangladesh, increasing the risk of viral adaptation, the potential for cross‐species transmission, and threatening the poultry sector and public health.
SN - 1750-2640
SN - 1750-2659
ER -