Tetanus toxin fragment C-specific priming by intranasal infection with recombinant Bordetella pertussis.

As an alternative to parenteral administration, mucosal administration offers several advantages including the ease of administration, safety and the ability to induce mucosal immunity. As a first step towards nasal administration of important childhood vaccines, we have previously developed attenuated Bordetella pertussis strains able to protect mice against pertussis upon nasal vaccination. Since pertussis vaccines are generally combined with tetanus and diphtheria vaccines, we constructed recombinant B. pertussis strains producing the non-toxic protective tetanus toxin fragment C (TTFC). TTFC was genetically fused to the N-terminal domain of the B. pertussis filamentous haemagglutinin. The hybrid gene was introduced into B. pertussis both on a multi-copy replicative plasmid and as a single copy inserted into the chromosome of a pertussis toxin-producing strain and a toxin-deficient attenuated strain. The hybrid protein was secreted by the recombinant strains. However, the recombinant multi-copy plasmid was unstable in vivo, and immunisation could only be carried out with the strains containing the single-copy chromosomal integration. Both the toxin-producing and the toxin-deficient recombinant B. pertussis strains were able to prime mice for the production of anti-TTFC serum antibodies upon intranasal administration, suggesting the feasibility of using recombinant attenuated B. pertussis for the development of combined childhood vaccines.