IMMUNE-RESPONSES AND PROTECTION AGAINST BORDETELLA-PERTUSSIS INFECTION AFTER INTRANASAL IMMUNIZATION OF MICE WITH FILAMENTOUS HEMAGGLUTINININ SOLUTION OR INCORPORATED IN BIODEGRADABLE MICROPARTICLES

The intranasal (i.n.) immunization of mice with Bordetella pertussis f ilamentous haemagglutinin (FHA) either as a solution or incorporated i n biodegradable microparticles induced very similar immune responses. Both resulted in strong systemic IgG responses to FHA and good levels of anti-FHA IgG and IgA in the lungs of immunized mice. In comparison, the intraperitoneal (i.p.) immunization of mice with FHA, as a soluti on, engendered anti-FHA antibody responses which were stronger for ser um IgG, similar for lung IgG and lower for lung IgA. The anti-FHA anti body levels, as measured by immunosorbent assay, were shown to correla te with their functional activity in the blocking of B. pertussis adhe sion to HeLa tissue-culture cells. All three forms of immunization app eared to stimulate T-cell responses as assessed by in vitro antigen-sp ecific spleen cell proliferation and IL-2 secretion indicative of a Th 1 type response, however, cells from i.p. immunized mice only secreted low levels of IL-5. All three methods of FHA immunization provided mi ce with significant protection against subsequent aerosol challenge wi th virulent B. pertussis. Mice which had been immunized intra-nasally eliminated the bacteria from their lungs slightly more rapidly than i. p. immunized mice, demonstrating the efficacy of intranasal administra tion of FHA in solution and in the more practical biodegradable microp article form.