Extensive Epitranscriptomic Methylation of A and C Residues on Murine Leukemia Virus Transcripts Enhances Viral Gene Expression

The data presented in the present study demonstrate that MLV RNAs bear an exceptionally high level of the epitranscriptomic modifications m 6 A, m 5 C, and Nm, suggesting that these each facilitate some aspect of the viral replication cycle. Consistent with this hypothesis, we demonstrate that mutational removal of a subset of these m 6 A or m 5 C modifications from MLV transcripts inhibits MLV replication in cis , and a similar result was also observed upon manipulation of the level of expression of key cellular epitranscriptomic cofactors in trans . Together, these results argue that the addition of several different epitranscriptomic modifications to viral transcripts stimulates viral gene expression and suggest that MLV has therefore evolved to maximize the level of these modifications that are added to viral RNAs.