By contrast to TZM-gfp co-cultures at 48 h, equal numbers of PBMC from this patient co-cultured with Molt4-CCR5 cells had no detectable p24 antigen at the same timepoint (Fig. 5B, blue data points), arguing that increases in p24 at 48 h of TZM co-culture was due to transfer and productive infection of TZM-gfp cells, and not sustained release of virions from infected primary PBMC. Here, CCR5 is linked to infection.