FIG. 1.

Serum F1-V-, F1-, or V-specific IgG titers following i.m. immunization with F1-V fusion protein in a Swiss Webster mouse plague model. Mice were given two immunizations at day 0 and day 28 (d28) with 10 μg F1-V fusion protein by i.m. injection. Unimmunized mice were used as negative controls. Each group contained 10 mice. (A) Anti-F1-V IgG titers at day 28. (B) Anti F1-V IgG titers at day 42. (C) Anti-F1 IgG titers at day 42 and protection efficacy following challenge with 1,000 LD₅₀ Y. pestis via the s.c. route. (D) Anti-V IgG titer at day 42. The bars represent means, and the circles represent titers for individual mice. AL, Alhydrogel.