SRSF1 and HIV-1 infection: Taken together, the results found for cellular splicing factors in macrophages suggest that HIV-1 infection changes the splicing factor milieu in these cells in such a way that might be expected to aid virus replication in the first week or two i.e. increased levels of splicing enhancing factor(s), including SC35 but probably not ASF/SF2, and lower levels of the competing inhibitory hnRNPs A/B and H, leading to increased tat mRNA expression and ultimately virus production.