Abstract Title
Different Patterns of Pathogenicity and Transmission of Infection with Highly Pathogenic Avian Influenza A(H5Nx) Virus in Herring Gulls
Abstract
The evolution of novel clade 2.3.4.4b H5 viruses has led to highly transmissible variants with severe impacts to poultry, wildlife, mammals, and recently dairy cows. As natural hosts, gulls contribute to the genetic diversity and spread of influenza A viruses (IAVs). In Canada, most index HPAI H5Nx viruses documented from 2021 to 2023 were initially isolated from gull species, especially Great Black-Backed Gulls (Larus marinus). In this study, we evaluated the pathogenicity and transmission dynamics of three clade 2.3.4.4b H5 viruses in Herring Gulls (Larus argentatus).
We observed significant differences in mortality and clinical signs among gulls infected with theses viruses. The bovine-origin B3.13 H5N1 virus caused 10% mortality and mild clinical disease, whereas fox-origin reassortant H5N1 virus led to notable pathologies and higher mortality. The H5N5 virus isolated from Nova Scotia from a herring gull was the most virulent, causing over 75% mortality and prominent neurological signs. All three viruses efficiently transmitted to naïve contacts in a co-habitation experiment, with virus replication confirmed in respiratory and digestive systems through elevated virus titres in oropharyngeal and cloacal swabs.
All contact gulls exposed to B3.13 H5N1 survived with mild clinical signs, while high mortality occurred among those exposed to the other two viruses. Notably, a rapid decline in antibody titres across all 3 viruses in recovered gulls suggests a potential for recurrent infection and further virus dispersal by gulls. Should viruses like B3.13 spill over into wild bird/mammal populations, they may persist and spread within diverse ecological niches.
We observed significant differences in mortality and clinical signs among gulls infected with theses viruses. The bovine-origin B3.13 H5N1 virus caused 10% mortality and mild clinical disease, whereas fox-origin reassortant H5N1 virus led to notable pathologies and higher mortality. The H5N5 virus isolated from Nova Scotia from a herring gull was the most virulent, causing over 75% mortality and prominent neurological signs. All three viruses efficiently transmitted to naïve contacts in a co-habitation experiment, with virus replication confirmed in respiratory and digestive systems through elevated virus titres in oropharyngeal and cloacal swabs.
All contact gulls exposed to B3.13 H5N1 survived with mild clinical signs, while high mortality occurred among those exposed to the other two viruses. Notably, a rapid decline in antibody titres across all 3 viruses in recovered gulls suggests a potential for recurrent infection and further virus dispersal by gulls. Should viruses like B3.13 spill over into wild bird/mammal populations, they may persist and spread within diverse ecological niches.
Co-Author(s)
Jolene A. Giacinti1, Tamiru Alkie2, Carissa Embury-Hyatt2, Anthony Signore2, Frank Baldwin3, Janet Ng3, Trevor Thomson3, Darwin Ramos2, Richard Webby4, Yohannes Berhane2
1.Science and Technology Branch, Environment and Climate Change Canada, Government of Canada
2.National Centre for Foreign Animal Disease, Canadian Food Inspection Agency, Government of Canada
3.Canadian Wildlife Service, Environment and Climate Change Canada, Government of Canada
4.Department of Infectious Diseases, St. Jude Children's Research Hospital
Abstract Category
Transmission pathways, pathobiology, immune responses