EWSR1 and infection: In contrast, the level of EWSR1 in B cells infected with mutant virus carrying anti-EWSR1 shRNAs was reduced to a level below that of wild-type virus, demonstrating effective shRNA-mediated repression of EWSR1 in vivo. Together, these results demonstrated that anti-EWSR1 shRNAs expressed downstream of vtRNA5 in the TMER5 transcriptional unit are fully functional during MHV68 infection.