FIG. 7.

Complement kinetics and components. (A and B) Kinetics of VACV EV neutralization activity in vitro of murine anti-B5 MAbs (B126 and B96) at 10 μg/ml in the absence or the presence of rabbit complement. Data are shown as plaque numbers. One of three independent experiments is shown. VACV EV is fully neutralized by anti-B5 MAb B126 within 5 min of the addition of complement. (C) VACV EV neutralization by the anti-B5 MAb and the addition of normal human serum (NHS) complement or C1q-, C3-, or C5-depleted serum. Specific VACV EV neutralization in the absence of C3 was statistically significant compared to the value for normal human serum (P < 0.003). One of three independent experiments is shown. Error bars indicate SEM for each group.