Previous studies implicated resting and activated CD4+ T cells (Gupta et al., 2002; Hu et al., 2004; Veazey et al., 2003; Zhang et al., 1999), while others concluded that Langerhans cells (LC), dendritic cells, and macrophages (Collins et al., 2000; Hu et al., 2000, 2004; Kawamura et al., 2000; Spira et al., 1996) were the likely first targets of HIV-1 infection in the human lower reproductive tract. Here, CD4 is linked to HIV-1 infection.