 Immunogenicity testing will include IgG antibody responses to each vaccine antigen, by a qualified indirect enzyme-linked immunosorbent assay ELISA, on serum or plasma obtained prior to each study vaccination and at time points after each vaccination see Appendix A; the functional activity of vaccine-induced antibodies will be assessed by in vitro enzyme neutralization assays; the induction of B cell memory will be measured by antigen-specific memory B cell responses. 