After infection with the PRRSV SX-1 strain, PSF and P54 protein expression was upregulated (Fig. 2A), and the antisense pathway was the most variable of all the significant signaling pathways for the highly virulent SX-1 strain; however, this finding was not observed in the signaling pathways for the moderately virulent ZCYZ strain or the mildly virulent SD1 strain (Fig. 2A). The gene discussed is SFPQ; the disease is infection.