Of interest, this rule does not apply for 3 isolates (#28, #9 and #39) that, in T-CD4+ cultures, poorly replicated (p24 production at 7 days post infection <12.5 pg/ml), but reached high levels of HIV DNA copies (406,714 copies/106 cells; 78,869 copies/106 cells; 76,049 copies/106 cells, respectively (Figure 5, panel B). This evidence concerns the gene CD4 and infection.