Entry efficiency, PSC-RANTES and sCD4 sensitivity of R5 viruses evolving over time in BT78, CC39 and DN57. Entry of luciferase reporter viruses expressing CCR5-using Envs into TZM-bl cells expressed as relative light unit (RLU) (A), and susceptibility of the reporter viruses to neutralization with PSC-RANTES (B) and sCD4 (C) were determined. The numbers in the brackets indicate the number of clones analyzed at each time point and values above the bars indicate fold increase in sCD4 sensitivity relative to that of the w2 viruses. * P<0.05 (Mann-Whitney U test). Data are representative of 2-3 independent experiments (error bars, s.d.).