CD4 and infection: HIV transcription was detectable only in a small number of CD4+ T cells—less than 0.000016% or 16.4 per million cells—of people with HIV with viral suppression on ART (Finzi et al, 1997; Wong et al, 1997), whereas another study suggested an infection frequency of 0.01–0.001% (Siliciano et al, 2003).