CD4 and HIV infectious disease: In particular, as CD4+ T cells are the target cells of HIV infection, HIV infection leads to an extensive increase in m6A levels in both host and viral mRNAs, thereby influencing HIV replication and viral RNA nuclear export.316 During the latent phase of HIV-1 infection, NSUN1 binds with HIV-1 TAR RNA at the 5′ long terminal repeat and generates its m5C methylation, and NSUN1 binding with TAR competes with Tat–TAR interaction, leading to hampered HIV-1 transcriptional elongation and viral latency in CD4+ T cells.317