In the HIV-1 genome, the single stranded positive sense RNA contains m6A modifications at multiple sites in both the untranslated and coding regions.
[8] The modification in respiratory syncytial virus families showed a positive role and enhanced viral replication and infection.
[5] Most of the RNA viruses carry out their cycles in the cytoplasm, away from the required machinery for writing and erasing m6A modifications which are housed in the nucleus.
[5] For DNA viruses, that cycle in the nucleus with direct access to said machinery, no clear general positive or negative regulatory role can be attributed to m6A modifications.
[10] These modifications regulate important functions of viral RNA such as metabolism and immune system interactions.
NSUN2 is the complex that codes the cytidine methyltransferases credited with m5C formation in cells and amplification in viral epitranscriptomes.
[13] Viral RNA modifications play important roles in interactions with the immune system of host cells.
The m6A modification of viral RNAs allows for the viruses to escape recognition by the retinoic acid inducible gene-I receptor (RIG-I), in the type 1 IFN response, a crucial pathway of innate immunity.
The cap structures help viral RNA to blend in among modified cellular mRNA and avoid triggering immune response systems.