FIGURE 6.

Interference of low concentrations of PI with cleavage at the NC-SP2 processing site. A, virus was prepared from the supernatant of HeLa cells grown in the presence of the indicated concentrations of LPV. Virus samples were separated by SDS-PAGE on 16.5% Tris-Tricine gels and analyzed by quantitative immunoblotting using the indicated antisera. The positions of NC-SP2 and NC as well as CA-SP1 and CA are marked. B, relative infectivities of the respective virus samples were determined by titration as described previously (47). Data represent mean values and standard deviations from triplicate measurements. The curve shows nonlinear regression to a standard dose-response equation.