Protection and immune response in pigs intradermally vaccinated against porcine reproductive and respiratory syndrome (PRRS) and subsequently exposed to a heterologous European (Italian cluster) field strain.

The purpose of this study was to assess the immune response in pigs intradermally vaccinated with a commercially available attenuated porcine reproductive and respiratory virus (PRRSV) vaccine (Porcilis PRRS) and subsequently exposed to a heterologous (Italian cluster) field strain of virulent PRRSV. A total of 18, 4-week-old pigs seronegative for PRRSV were allocated to 1 of 3 groups (groups A, B, and C). At 5 weeks of age, pigs of groups A (n=6 pigs) and B (n=6 pigs) were vaccinated intramuscularly and intradermally, respectively, with Porcilis PRRS.