Pro-inflammatory cytokine gene expression can be differently modulated by the PRRSV isolate causing infection;
PRRSV infection can increase FoxP3 gene expression as a marker of Treg activation;
PRRSV vaccination could maintain FoxP3 lower expression overtime;
FoxP3 modulation does not appear strictly associated with IL-10 gene expression;
Treg activation could be a suitable parameter to evaluate the immunomodulatory effect of different PRRSV isolates.