FIG. 4.

Comparison of the flow cytometric and plaque reduction neutralization assays. Purified WR-GFP was incubated with dilutions of hyperimmune rabbit serum (A and B) or human VIG (C and D) in duplicate as for Fig. 3 for the flow cytometric assay (A and C) or as described in the text for the plaque reduction assay (B and D). Experiments were done in duplicate and bars indicate standard deviations. The percentage of neutralized virus was determined by comparing the numbers of GFP-expressing cells or plaques in the presence and absence of serum.