CPSF4 and infection: Primer extension analysis of total B2 RNA levels also confirmed that depleting CPSF30 but not CPSF73 prevented infection-induced SINE ncRNA accumulation during infection (Fig. 3G), further suggesting that polyadenylation, which is known to stabilize B2 SINE ncRNA (21), promotes the increased abundance of these Pol III transcripts during MHV68 infection.