Conserved HA-peptides expressed along with flagellin in Trichoplusia ni larvae protects chicken against intranasal H7N1 HPAIV challenge

•Extracts of T.ni larvae expressing flagellin-NG34/CS17 protected chickens against a heterologous H7N1 IV strain.•Flagellin-NG34/CS17 vaccinated chickens saved from flu-like clinical signs.•Flagellin-NG34/CS17 vaccinated chickens limited oropharyngeal and cloacal shedding.•Flagellin-NG34/CS17 induced an increase in IgM and improved IgY response. The immunization of poultry where H5 and H7 influenza viruses (IVs) are endemic is one of the strategies to prevent unexpected zoonoses. Our group has been focused on conserved HA-epitopes as potential vaccine candidates to obtain multivalent immune responses against distinct IV subtypes. In this study, two conserved epitopes (NG-34 and CS-17) fused to flagellin were produced in a Baculovirus platform based on Trichoplusia ni larvae as living biofactories. Soluble extracts obtained from larvae expressing “flagellin-NG34/CS17 antigen” were used to immunize chickens and the efficacy of the vaccine was evaluated against a heterologous H7N1 HPAIV challenge in chickens. The flagellin-NG34/CS17 vaccine protected the vaccinated chickens and blocked viral shedding orally and cloacally. Furthermore, no apparent clinical signs were monitored in 10/12 vaccinated individuals. The mechanism of protection conferred is under investigation.