FIG. 7.

Reextending the C terminus of p14 with scrambled sequences, but not random sequences, restores pore formation and syncytiogenesis. (A) The nonfusogenic p14c78 truncation was reextended to full length with either a scrambled version of the deleted amino acids (Sc) or the same number of random amino acids (Ra). These constructs, along with p14, p14c105, and p14c78, were transfected into QM5 cells using amounts of DNA to give equalized surface expression levels. Transfected cells were fixed and Giemsa stained at the indicated times posttransfection, and a syncytial index based on the numbers of syncytial nuclei/microscopic field was determined. Results are the means ± SD from one of three experiments conducted in triplicate. (B) QM5 cells were cotransfected with pEGFP and the indicated p14 constructs at plasmid doses that yielded equivalent cell surface expression levels, and transfected cells were cocultured with Vero target cells labeled with calcein red-orange. Cells were resuspended and fixed 7 h posttransfection, and the percent pore formation was determined by flow cytometry and Overton subtraction as described in the legend of Fig. 5. Results are the means ± SD from one of two experiments conducted in triplicate.