Immunogenicity and Efficacy of Digitally Immune Optimised H1N1 Vaccine Candidates in Swine and Murine Animal Models

Influenza A virus (IAV) zoonotic transmission and constant evolution in multiple species heightens the risk of emerging novel strains at the human-animal interface. Composite antigens including hemagglutinin (HA), neuraminidase (NA), and matrix-2 (M2) proteins were computationally designed to maximize the breadth of the immune response elicited to human seasonal, pandemic, and zoonotic H1N1 IAVs. Mouse hyperimmune serum raised against these antigens demonstrated broad H1 neutralization and N1 inhibition activity. To enhance immunogenicity, the antigens were combined as a single DNA expression construct (DVX-H1N1). Studies in the well-recognized swine model for human influenza demonstrated that DVX-H1N1 immunization induced broad, neutralizing antibody responses and markedly reduced nasal shedding of viral RNA following challenge with 1A.3.3.2 subclade strain A/swine/England/1353/2009 (H1N1). An effective immune response and reduction in virus shedding was observed in pigs immunized with a whole inactivated virus (WIV) vaccine homologous to the challenge strain but not with a human-origin seasonal WIV vaccine. Overall, we demonstrated broad immunogenicity and efficacy of the DVX-H1N1 vaccine candidate, benchmarked against relevant IAV H1N1 strains in vitro and in vivo in mice and pigs. IMPORTANCEThe zoonotic potential of swine-origin IAVs is a recognized global health threat. Vaccination remains the most effective intervention against influenza; protecting at the population level by preventing nasal shedding and transmission, but also in individuals by limiting clinical disease, particularly by reducing the severity of lung infection. The World Health Organization (WHO) spearheads biannual surveillance efforts to review evolving virus strains and vaccine antigens at Vaccine Candidate Meetings (VCM) to recommend strain updates for the human seasonal influenza vaccine and for pandemic preparedness purposes. However, the strain selection approach is complex and efficaciousness of seasonal influenza vaccines still varies significantly based on the accurate matching of the predicted strains in circulation with the manufactured vaccine antigens. This emphasizes the need for next-generation influenza vaccines that improve the breadth and longevity of immunity. We describe a computationally optimized DNA vaccine with broad immunogenicity and robust efficacy in the pig model.