Up-regulation of IL-10 upon PRRSV vaccination impacts on the immune response against CSFV

Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) infection negatively impacts the efficacy of classical swine fever virus (CSFV) vaccine. This paper investigates whether the PRRSV vaccine also impacts the CSFV vaccine and if the impact is time-related. Forty-eight piglets born from four sows were divided into five groups (G1-G5). The piglets in G1 to G4 were given PRRSV vaccine at 14, 21, 28 and 35 days of age. The G5 group was not vaccinated with the PRRSV. All pigs were given the CSFV vaccine at 35 days of age. Immune responses to the CSFV vaccine were evaluated by testing CSFV-specific sera antibodies, lymphocyte proliferation and cytokine secretion. The results demonstrate that the PRRSV vaccine significantly reduces the immune responses of the CSFV vaccination when immunised both vaccines at the same time or with only a one week interval. The PRRSV vaccination induced higher levels of IL-10 expression in the first week and this may be why the CSFV vaccination is immunosuppressed. The findings indicate that a time interval of more than one week is necessary for vaccinated CSF after the PRRSV immunisation.