Moreover, Shibayama et al. [32] showed an inverse association between TTV levels and CD4 + T lymphocyte levels in HIV-1-positive persons: they investigated the prevalence and relative titer of TTV DNA among 144 patients with HIV infection by polymerase chain reaction (PCR) methods and found a higher prevalence of TTV DNA in HIV-infected patients than in controls (91% versus 27%); they also found a higher titer in HIV patients infected with AIDS, those with a low CD4 T cell count, or those with high HIV viral loads [32]. The gene discussed is CD4; the disease is AIDS.