CD4 and HIV infectious disease: In contrast to serum viral DNA analyses, no significant difference was observed in the overall prevalence of anti-PyV antibodies to the five PyVs tested between HIV-positive and -negative groups (Fig. 1), While seroreactivities might be impaired in the subset of HIV + individuals with low CD4 count and therefore the interpretation of the results should be limited, it appears that anti-PyV IgGs are potentially induced and maintained by antigenic stimulation through primary and latent infection with PyVs regardless of HIV infection.