CCR5 and infection: Interestingly, as mentioned in the introduction, a two-phase trans-infection model has already been proposed for CCR5-tropic HIV-1 strains with the late phase being virus replication-dependent in in vitro-generated MDDCs and in mucosal DCs studied ex vivo (Turville et al., 2004; Harman et al., 2009; Nasr et al., 2014).