CD44 and HIV-1 infection: It is tempting to speculate that in the context of HIV-1 infection Tat conceals itself, an ability that may relate to the highly unstructured and very flexible conformation of the protein [63], as well as to its known ability to bind through the basic region the heparan sulfate proteoglycans present in the extracellular matrix and on the cell membrane [64], thus avoiding antibody recognition and priming (or boosting) of B cell responses.