Research note: Use of in vitro and in ovo approaches to characterise avian influenza viruses and assess species specific responses to infection.

Circulation of avian influenza viruses (AIVs) in domestic and wild birds poses a major health threat, requiring a rapid approach to characterize and identify high-risk strains. We evaluated virus replication kinetics and host viability with low pathogenicity avian influenza (LPAI) H6N1 and genetically modified avian influenza GM-AIV09 viruses in embryonated eggs and avian cell lines. Virus titres increased steadily in a 72-hour infection in DF-1 cells and embryonated hens' eggs but peaked at 48 hours in CCL-141 cells and embryonated duck eggs. CCL-141 cells exhibited greater virus-induced cell death than DF-1 cells, whereas duck embryos maintained higher viability than chicken embryos. Additional work is needed to establish if there are breed specific differences which may impact categorisation of AIVs using embryonated eggs. Use of embryonated eggs better mirrored relative avian species survivability to AIV infection than use of avian cells.