Our findings that M-CSF production was a common feature of HIV-1 and HIV-2 infection imply a greater role of M-CSF in the establishment and maintenance of lentivirus infection, including a role in the re-activation of virus reservoirs [75], and the above effects may be associated with the ability of M-CSF to facilitate macrophage differentiation into an M2 phenotype [65,66,75]. Here, CSF1 is linked to lentivirus infection.