Endoribonuclease activities of porcine reproductive and respiratory syndrome virus nsp11 was essential for nsp11 to inhibit IFN-β induction.

Previous studies have shown that PRRSV nsp11, which was an endoribonuclease, was an interferon antagonist, however, the mechanism that nsp11 inhibited IFN-β production was unclear. To explore whether the endoribonuclease was required for nsp11 to disrupt the IFN-β production, substitutions of the presumed catalytic histidine and lysine residues of nsp11 were introduced into plasmid pcDNA 3.1-FLAG. The results showed that mutation that inactivated endoribonuclease made nsp11 lose its ability to inhibit Poly(I:C)-induced IFN-β promoter activity. In conclusion, our present work indicated that the endoribonuclease activity of nsp11 was essential for nsp11 to inhibit the IFN-β induction.