Marika Koszegi, Université de Montréal

Marika Koszegi, Centre de Diagnostic Vétérinaire de l'Université de Montréal (CDVUM), Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada, Mehdi Maury Lajouedj, Swine and Poultry Infectious Diseases Research Center (CRIPA-FRQ), Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada, Vincent Baby, Centre de Diagnostic Vétérinaire de l'Université de Montréal (CDVUM), Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada, Carl A. Gagnon, Centre de Diagnostic Vétérinaire de l'Université de Montréal (CDVUM) and Swine and Poultry Infectious Diseases Research Center (CRIPA-FRQ), Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada

Discovering & Evolving

Fowl aviadenoviruses (FAdV) species D and E are the etiological agents of inclusion body hepatitis (IBH) in poultry. No treatment is available to cure infected fowls, but autogenous vaccines are widely used in Quebec, Canada, to prevent IBH. The autogenous vaccine's efficacy, however, depends on its genomic/antigenic similarity to the field-involved virus strain, which is usually identified using partial hexon gene sequencing. This region represents only 1.24% of the whole genome. The hypothesis for this study is that whole-genome sequencing (WGS) will give more information to veterinarians to adjust their vaccination strategies. Liver samples were either directly sent to the Molecular Diagnostic Laboratory of CDVUM for FAdV qPCR analysis by Québec poultry veterinarians, or by the Quebec Ministry of Agriculture, Fishery and Food following the necropsy of dead birds. Positive samples were then selected, and whole-genome sequencing of FAdV was carried out using Illumina's MiSeq platform. Out of 134 qPCR FAdV-positive cases, 106 complete and 5 partial FAdV sequences were obtained. Among those sequences, 73, 24, and 9 sequences were classified as genotypes E/8b, E/7, and D/2, respectively. Only type E strains were found between 2020 and 2023, while type D/2 strains were newly identified in 2024. Interestingly, WGS changed the classification of 31.13% FAdV strains compared to the partial hexon gene sequencing method. This study gives us a better insight into the genomic diversity of FAdV strains present in Quebec poultry flocks. Rapid identification of new strains could help practitioners adapt their autogenous vaccine strategy.