Furthermore, the omission of C-T-C transmission from the HIV-1/HTLV-I co-infection model leads to an under-evaluation of the basic HIV-1 mono-infection reproductive ratio [[3]]. The authors have shown that humoral immunity does not play the role of clearing an HIV-1 infection, but it can control HIV-1 infection. During the early 1980s, the first 3 human retroviruses were identified: human T-lymphotropic virus 1 and 2 (HTLV-1 and HTLV-2) and human immunodeficiency virus (HIV). [Extracted from the article]