CD4 and infection: We infected HSC-F - a CD4+ T cell line established from cynomolgus monkey - in vitro with SHIV-KS661 at four different multiplicities of infection (MOI) and measured the concentration of Nef-negative (susceptible/target) and Nef-positive (infected/virus producing) HSC-F cells [cells/ml], and the total [RNA copies/ml] and infectious [TCID50/ml] viral load daily over nine days.