To test the possibility that P. clara might inhibit intestinal infection of coronavirus through degradation of trypsin and TMPRSS2, we used murine hepatitis virus-2 (MHV-2), a mouse-tropic coronavirus that requires trypsin or TMPRSS2 to facilitate cleavage of S protein and fusion with cells4,5, like SARS-CoV and SARS-CoV-232–34. The gene discussed is TMPRSS2; the disease is digestive system infectious disorder.