Diverse infectivity, transmissibility, and pathobiology of clade 2.3.4.4 H5Nx highly pathogenic avian influenza viruses in chickens

• Published in: Emerging microbes & infections Vol. 12; no. 1; p. 2218945
• Main Authors: Kwon, Jung-Hoon, Bertran, Kateri, Lee, Dong-Hun, Criado, Miria Ferreira, Killmaster, Lindsay, Pantin-Jackwood, Mary J., Swayne, David E.
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 31-12-2023; Taylor & Francis Group
• Subjects: Animals; Avian influenza virus; chicken; Chickens; clade 2.3.4.4; Disease Outbreaks; highly pathogenic avian influenza virus; infectivity; Influenza A virus; Influenza A Virus, H5N1 Subtype; pathogenicity; Sepsis; transmissibility; pathogenicity; chicken; transmissibility; Avian influenza virus; highly pathogenic avian influenza virus; clade 2.3.4.4; infectivity
• ISSN: 2222-1751; 2222-1751
• DOI: 10.1080/22221751.2023.2218945

Clade 2.3.4.4 Eurasian lineage H5Nx highly pathogenic avian influenza virus (HPAIV) has become the globally dominant clade and caused global outbreaks since 2014. The clade 2.3.4.4 viruses have evolved into eight hemagglutinin subgroups (2.3.4.4a-h). In this study, we evaluated the infectivity, pathobiology, and transmissibility of seven clade 2.3.4.4 viruses (two 2.3.4.4a, two 2.3.4.4b, one 2.3.4.4c and two 2.3.4.4e) in chickens. The two clade 2.3.4.4e viruses caused 100% mortality and transmissibility in chickens. However, clade 2.3.4.4a and c viruses showed 80-90% mortality and 67% transmissibility. Clade 2.3.4.4b viruses showed 100% mortality, but no transmission to co-housed chickens was observed based on lack of seroconversion. All the infected chickens died showing systemic infection, irrespective of subgroup. The results highlight that all the clade 2.3.4.4 HPAIVs used in this study caused high mortality in infected chickens, but the transmissibility of the viruses in chickens was variable in contrast to that of previous Eurasian-lineage H5N1 HPAIVs. Changes in the pathogenicity and transmissibility of clade 2.3.4.4 HPAIVs warrant careful monitoring of the viruses to establish effective control strategies.