However, a small proportion of EC developed declining number of CD4+ T cells despite undetectable levels of HIV-1 viremia as HIV-1 patients with progressive disease, that was associated to reduced thymic output mirrored by thymic dysfunction during untreated progressive HIV-1 infection (Hunt et al., 2008; Okulicz et al., 2009; Sedaghat et al., 2009; Yang et al., 2012). Here, CD4 is linked to HIV-1 infection.