CD4 and HIV infectious disease: However, variations in CCL3L1-CCR5 by impacting on (i) risk of acquiring HIV infection, (ii) viral load, (iii) rate and extent of CD4+ T cell depletion, and (iii) time from seroconversion to thresholds of CD4+ T cell counts at which antiviral therapy is initiated might confound the assessment of the currently used surrogates of vaccine endpoints.