Mean CD4 cell count and mean log10 viral load were significantly different between recent and non-recent infections (CD4 count, 543 v 451 cells/mm3; log10 viral load, 4.9 v 4.3; p < 0.001, Welch's t-test, with recency cut-off of 12 months) (Fig. 3A, B), but with high variance and substantial overlap between the distributions. This evidence concerns the gene CD4 and infection.