Thus, biologically active IL-1 is dramatically upregulated in bronchoalveolar fluids during PRRSV and LPS-driven respiratory disease (30); serum cytokine levels of IL-1 are upregulated early after PRRSV infection and are correlated with virus persistence (31); exacerbation of disease symptoms after PRRSV challenge is correlated with higher IL-1beta levels in serum (32). This evidence concerns the gene IL1B and respiratory system disorder.