Figure 2: Factors that enhance cis infection of APC also enhance trans infection. Inflammatory cytokines produced in response to HIV-1 infection and co-infections enhance various stages of HIV-1 infection of APC, including maturation of DC and activation of B cells. This in turn is essential for transfer of HIV-1 to CD4+ T cells and conferring them with the ability to produce prodigious amounts of HIV-1. *CXCR4 and CD209 expressed on activated APC.