FIG 1.
Neutralization of HIV-1 and SIV by huCD4, rhCD4-Ig, and rhCD4-Ig variants. (A) HIV-1 pseudotyped with the Env protein of the ADA isolate or wild-type SIVmac239 was preincubated for 1 h with human CD4-Ig, rhesus CD4-Ig, or rhesus CD4-Ig with the indicated amino acid substitution. TZM-bl cells were then added and incubated for 48 h. Luciferase expression was measured and normalized to expression in the absence of any CD4-Ig variant. (B) Experiment similar to that shown in panel A except that the SIVs (SIVmac1A11, SIVmac251, SIVsmE543-3, and SIVmac316) were preincubated with human CD4-Ig, rhesus CD4-Ig, or rhesus CD4-IgI39N. The results of each experiment are representative of at least two experiments with similar results. Error bars represent standard errors of the means (SEM).