Binding specificities of sera from VLP-immunized mice. (A) VP4-binding activities of individual antisera. (B) VP1-N75-binding activities of individual antisera. (C) SP70 peptide-binding activities of individual antisera. Each symbol represents an individual mouse, and the horizontal lines indicate the geometric mean values of the groups. Statistical significances were determined by one-way ANOVA using GraphPad Prism version 5. ns, P ≥ 0.05; *, P < 0.05; **, P < 0.01; ***, P < 0.001.