Virus-like particles as a vaccine against porcine reproductive and respiratory syndrome virus

Porcine reproductive and respiratory syndrome (PRRS) is the most significant infectious disease currently affecting the swine industry worldwide. Several inactivated and modified live vaccines (MLV) have been developed to curb PRRSV infections. The unsatisfactory efficacy and safety of these vaccines, drives for the development of new generation PRRS universal vaccines. Virus like particles (VLPs) based vaccines are gaining increasing acceptance compared to subunit vaccines, as they present the antigens in more veritable conformation and are even readily recognized by the immune system. Hepatitis B virus (HBV) core antigen (HBcAg) is very well studied and has been successfully used as a carrier for more than 100 other viral sequences. In this study, hybrid HBcAg VLPs are generated by fusion of the conserved protective epitopes of PRRSV and expressed in E. coli. An optimized purification protocol that overcomes issues from ultracentrifugation is developed to obtain hybrid HBcAg VLP protein from the inclusion bodies. This hybrid HBcAg VLP protein self assembled to 23nm VLPs that were shown to block virus infection of susceptible cells when tested on MARC 145 cells. Therefore, the safety of non-infectious and non-replicable VLPs and production through low-cost E. coli fermentation may make this vaccine competitive against current vaccines on both efficacy and cost.