NSUN4 and infection: Among the host factors responsible for m5C modification, infection with influenza A virus downregulated NOP2 (two out of six experiments, also called NSUN1); upregulated NSUN3 (one of six experiments), NSUN6 (one of six experiments), and NSUN7 (three of six experiments but downregulated in one experiment), and did not affect the expression levels of NSUN2, NSUN4, or NSUN5.