CXCR4 and infection: The analysis of the efficiency of cis-infection of CD4+ T lymphocytes, Mø, and DCs by our panel of HIV-1 and HIV-2 primary isolates led us to conclude that the ability to productively infect Mø and DCs (i.e., to complete the viral replication cycle, allowing de novo production of viral particles) is independent of co-receptor usage (namely, CCR5, CXCR4, or CCR8).