The early-transmitting HIV-1 virions that succeed to establish a productive infection in vivo are CCR5 tropic and the ability to infect the α4β7 integrin+CD4+ CCR5+ T cell population in the mucosa (Nawaz et al., 2011; Peachman et al., 2015; Joseph et al., 2015). This evidence concerns the gene CCR5 and infection.