FIG. 5.

Infection kinetics mediated by CCR5(Δ18)-adapted envelopes in HeLa-CD4 cells expressing CCR5(Δ18). (A) Infection kinetics of HIV-gpt viruses pseudotyped with CCR5(Δ18)-adapted envelopes (V3 loop sequence S298N, N300Y, T315P) with or without the V4 N-glycan. Infections were terminated at each time point upon the addition of 25 μM TAK-779. Relative infectivity values were obtained by normalizing titers for each virus in CCR5(Δ18) cells at each time point to titers in HeLa-CD4 cells expressing a large amount of wild-type CCR5 at the final time point (10 h). The data were generated from the averages of three independent experiments. Error bars are standard errors of the means. (B) Mathematical analysis of the infectivity data. Infectivity data were analyzed according to the equations in reference 50. The x intercept denotes the lag phase and is the same for both viruses (∼15 min). The adapted virus lacking the V4 N-glycan has the steeper slope, indicating that it enters CCR5(Δ18) cells with a greater rate constant than the adapted virus with wild-type V4.