reports that viral polymerase complex and cellular splicing factor SF2/ASF jointly regulate the utilization of alternative 5’ splice sites in M pre-mRNA and control the M2 expression during infection [68, 69].Other study finds that cellular hnRNP K and NS1-BP proteins direct M segment splicing through binding 5’ splice site of M2 mRNA. Here, SRSF1 is linked to infection.