Whereas spontaneous viral clearance is associated with long term maintenance of tetramer+ CD4+ T cells, early loss of function followed by depletion of tetramer+ CD4+ T cells is observed in patients with evolving chronic hepatitis C. The impact of such T cell loss may be very significant, undermining both CD8+ T cell-mediated and B cell mediated immune responses in the long term which can be associated with accentuated escape from CD8+ T cells as has been observed in model and natural infection [20], [24]. This evidence concerns the gene CD4 and infection.