FIG. 1.

Immunogenicity and protection against NP challenge by intranasal immunization with 3P-CT in wild-type mice. (A) Serum antibody concentrations in response to proteins PsaA, PspC, and PdT in immunized mice. Serum antibody concentrations in response to these proteins were measured in C57BL/6 mice that were immunized intranasally with CT alone, 3P-CT, or WCV-CT. Serum samples were obtained 3 weeks after the last immunizations. Antibody concentrations were determined by ELISA; median concentration and interquartile range are shown. (B) Results of nasopharyngeal challenge of immunized mice. Mice immunized as described above were challenged with strain 0603 4 weeks after the last immunization. Tracheal aspirates obtained 1 week later were serially diluted and plated for quantification of colonization. Density of colonization of each individual mouse is shown; lines represent the median densities of colonization.