Development of efficacious replicon particle vaccines for swine influenza virus
Swine influenza virus is endemic in the United States swine population. Vaccination of swine against influenza is the most reliable method for decreasing influenza infection in swine. Therefore, new swine influenza vaccines that can be produced rapidly to respond to emerging subtypes or clusters are needed. In these studies the alphavirus replicon technology was utilized to produce several different swine influenza vaccine candidates. A recombinant hemagglutinin (HA) protein vaccine protected against homologous pandemic H1N1 challenge at several different doses. Replicon particle (RP) vaccines expressing the HA proteins of pandemic H1N1 and an H3N2 virus also protected against subsequent homologous challenge. Further, an RP vaccine expressing the conserved nucleoprotein (NP) of an H3N2 provided a level of protection against heterologous pandemic H1N1 challenge. In addition to evaluating the efficacy, these studies also demonstrate the safety of swine influenza RP vaccines. The HA RP vaccine was not shed or spread from vaccinated animals and no reversion to virulence was detected following vaccination of both host and non-host species. Thus, these studies demonstrate that swine influenza RP vaccines are both safe and efficacious.