CD4 and HIV infectious disease: Viruses coated with the vesicular stomatitis virus (VSV) G glycoprotein, which entry is CD4-independent, efficiently infected either differentiated THP-1 or THP-1-CD4R cells but not their undifferentiated monocytic counterparts, as monocytes are reported to be non-permissive to HIV infection in part because of post-entry blocks [17,18] (Figure 6).