While most anti-gp120-directed antibodies, and in particular those directed against the gp120 CD4 binding site displayed a reduced activity during viral cell-to-cell transmission, the same group reported that the T20 fusion inhibitor targeting the gp41 transmembrane glycoprotein as well as neutralizing antibodies directed against gp41 maintained their activity and were thus able to block both cell-free and cell-to-cell infection with the same efficiency. This evidence concerns the gene CD4 and infection.