FIG. 3.

Virus entry mediated by mutant glycoprotein constructs. (A) A trans-complementation assay measuring expressed CAT activity was utilized (21). Subsequent to single-round infection with an Env-complemented defective NL4-3-CAT vector, CEMx174 cells were lysed and the CAT activity was measured. Acetylated and nonacetylated forms of [¹⁴C]chloramphenicol were resolved using thin-layer chromatography. (B) For each construct, CAT activity was calculated from the percent conversion of nonacetylated to acetylated forms. The CAT activity, relative to that in the wild type (WT), for the chromatogram in panel A is shown. Mock, mock-transfected supernatants.