A novel vaccine combined with an alum adjuvant for porcine encephalomyocarditis virus (EMCV)-induced reproductive failure in pregnant sows

Abstract

To evaluate a novel vaccine for porcine encephalomyocarditis virus (EMCV), which causes reproductive failure in pregnant sows, virus like particles (VLPs) were generated and immunized twice in 2week intervals before sow mating. Sows were divided into 4 groups (n=4, per group). Group 1 was immunized with the alum adjuvant alone, Group 2 with VLPs alone, Group 3 with VLPs mixed alum adjuvant, and Group 4 with a commercial killed vaccine. In Group 2, seroconversion was observed at very low levels, while in Group 3, neutralizing antibodies were maintained at a high level until 30days after farrowing. Similar levels neutralizing antibodies were observed in Group 4. The gestation period of the pregnant sows was on average 115days, and no injection site reaction or side effects were observed. The mean temperature of the sows after immunization increased temporarily to 38.7–39.1°C for 1day. The numbers and weights of surviving piglets were similar among the groups. These data describe a novel EMCV vaccine composed of VLPs mixed with an alum adjuvant that is safe to use during sow gestation and induces and maintains high levels of seroconversion. This vaccine could thus be a candidate for protecting against EMCV induced reproductive failure in pig farms.