In line with their high affinity for CD4, the CD4low adapted envelopes already established a firm CD4 binding during the 30 minute spinoculation at 4°C, reaching a mean of > 40% of the maximal infection (CD4low.c21 at 47.4% and CD4low.c24 at 42.4%; Fig 6C). This evidence concerns the gene CD4 and infection.