FIG. 3.
(A) Effect of envelope protein mutation on HTLV-1 infectivity in cell-free and cell-to-cell transmission assays. Virus particles were generated by transfection of pACH clones into 293T cells. Inoculation of the target B5 cells was initiated with filtered cell-free virus supernatants (Cell-Free) or by coculture with lethally irradiated 293T cells transfected with pACH clones as indicated (Cell-to-Cell). At 3 weeks postinfection, virus infectivity was determined by a p19 antigen ELISA. Representative data from three independent experiments are shown. cont, control. (B) Effect of the residue 101 mutation in SU protein on virus entry. Pseudotyped viruses were generated by cotransfection of 293T cells with pNL4-3SV-40Luc+Env- and pHTE, pHTE101, or VSV-G. Inoculation of HOS cells was initiated with each cell-free pseudotyped virus particle. At 2 days after infection, virus entry was monitored by luciferase activity (normalized for HIV-1 p24 antigen levels). Representative data are shown.