CD4 and infection: Using the parameter values listed in Methods and initial values V(0) = 1×10−3 RNA copies/ml, T(0) = 103 cells/μl, T*(0) = 0, M*(0) = 0, and C(0) = 0 in the one-compartment model, we showed that the population of CD4+ count declines from 103 cells/μl to about 200 cells/μl around the 6th year after infection (Fig 3A).