Abstract Title
Avian influenza HxN5: Evolution, Characterization, and Pathobiology in Different Bird Species
Abstract
Neuraminidase (NA) is a key glycoprotein of avian influenza viruses (AIVs) crucial for the viral life cycle. Its primary function is cleaving sialic acid receptors on host cells, facilitating the release of newly formed virions from infected cells. NA also plays significant roles in the virulence and adaptation of AIVs in poultry. Currently, nine NA subtypes (N1 to N9) are recognized, with the N5 subtype being one of the rarest.
In recent years, we have observed a notable increase in the prevalence of H5N5 viruses of clade 2.3.4.4B in wild birds, poultry, and mammals. In this study, we analyzed the prevalence of HxN5 subtypes, comparing the sialidase activity, replication efficacy, and antiviral susceptibility of 14 distinct HxN5 AIVs isolated from 1976 to 2024, including H2, H5, H6, H10, H12, and H14 subtypes. We further assessed the pathobiology of four different H5N5 viruses in chickens and ducks.
Phylogenetic and sequence analyses of Eurasian and American lineages indicated intercontinental spread, particularly from Europe to Canada and Japan. Recent H5N5 viruses, especially those isolated in 2023/2024, formed a distinct cluster characterized by a notable deletion in the NA stalk domain. We found that NA activity in the recent H5N5 viruses since 2020 was significantly higher than that of earlier H5N5 and other HxN5 subtypes, except for H2N5. Our studies revealed high susceptibility to NA inhibitors, despite significant variations in antigenicity, and demonstrated robust virus replication in avian cells in vitro, along with pathobiology and transmissibility in experimentally infected chickens and ducks.
In recent years, we have observed a notable increase in the prevalence of H5N5 viruses of clade 2.3.4.4B in wild birds, poultry, and mammals. In this study, we analyzed the prevalence of HxN5 subtypes, comparing the sialidase activity, replication efficacy, and antiviral susceptibility of 14 distinct HxN5 AIVs isolated from 1976 to 2024, including H2, H5, H6, H10, H12, and H14 subtypes. We further assessed the pathobiology of four different H5N5 viruses in chickens and ducks.
Phylogenetic and sequence analyses of Eurasian and American lineages indicated intercontinental spread, particularly from Europe to Canada and Japan. Recent H5N5 viruses, especially those isolated in 2023/2024, formed a distinct cluster characterized by a notable deletion in the NA stalk domain. We found that NA activity in the recent H5N5 viruses since 2020 was significantly higher than that of earlier H5N5 and other HxN5 subtypes, except for H2N5. Our studies revealed high susceptibility to NA inhibitors, despite significant variations in antigenicity, and demonstrated robust virus replication in avian cells in vitro, along with pathobiology and transmissibility in experimentally infected chickens and ducks.
Co-Author(s)
Maryna Kuryshko1, Elsayed M. Abdelwhab1
1Friedrich Loeffler Institute, Institute of Molecular Virology and Cell Biology (IMVZ), Greifswald - Insel Riems, Germany
Abstract Category
Transmission pathways, pathobiology, immune responses