Efficacy of a combined inactivated porcine reproductive and respiratory syndrome virus vaccine using North American and European strains in specific pathogen free pigs

• Types 1 and 2 porcine reproductive and respiratory syndrome virus (PRRSV) cause disease in pigs in Korea.
• A vaccine composed of one type 1 strain and two type 2 strains of PRRSV was developed.
• The vaccine was inactivated with binary ethylenimine (BEI).
• The inactivated multi-strain vaccine protected against challenge with the same virulent type 1 and type 2 strains of PRRSV.

In Korea, porcine reproductive and respiratory syndrome (PRRS) is caused by European (type 1) and North American (type 2) strains of PRRS virus (PRRSV). In the present study, the efficacy of a multi-strain PRRSV vaccine inactivated with binary ethylenimine (BEI) was evaluated in pigs. The vaccine contained one type 1 strain (GCEU0907) and two type 2 strains (GC4019 and GC6262). Three vaccinated groups (four pigs per group) and three mock vaccinated groups (four pigs per group) were challenged with infectious PRRSV (strains GC4019, GC6262 or GCEU0907), then euthanased at 28 days post-infection. Mean anti-PRRSV neutralising antibody titres were significantly higher in the vaccinated groups than in the mock vaccinated groups. Mean blood virus titres in the mock vaccinated groups were significantly higher than those in the vaccinated groups from 5 to 28 days post-infection. On pathological examination, there were less severe macroscopic and microscopic lesions in vaccinated pigs compared with mock vaccinated pigs.