Efficacy of Type 2 PRRSV vaccine against challenge with the Chinese lineage 1 (NADC30-like) PRRSVs in pigs.

The objective of the present study was to determine the cross-protection of Ingelvac PRRS MLV against challenge with the new lineage 1 PRRSV emerged in China in pigs. Two lineage 1 PRRSV strains (FJZ03 and FJWQ16 originated from recombination event between NADC30 and JXA1-like strain). We found that pigs vaccinated with the vaccine were protected against challenge with the FJZ03 as shown by fewer days of clinical fever, reduced lung pathology scores, lower PRRS virus load in the blood and developed broadly neutralizing antibodies with high titers to FJZ03. In contrast, vaccine provided limited protection against challenge with FJWQ16 with higher fever, lower antibody titers, lower neutralizing antibodies and higher viral loads in blood. These results demonstrate PRRSV-MLV provides incomplete protection against new lineage 1 PRRSVs.