Our evidences that unstimulated CD4+ T lymphocytes became susceptible to HIV-1 infection when the exosome-mediated stimulus was applied before but not after HIV-1 infection are highly reminiscent of previously published data on resting CD4+ T lymphocytes stimulated with anti-CD3/CD28 antibodies before or after HIV-1 challenge[33]. Here, CD4 is linked to HIV-1 infection.