Evaluation of a truncated recombinant flagellin subunit vaccine against Campylobacter jejuni

A recombinant protein comprising the maltose-binding protein (MBP) of Esche richia coli fused to amino acids 5 to 337 of the FlaA flagellin of Campylob acter coli VC167 was evaluated for immunogenicity and protective efficacy a gainst challenge by a heterologous strain of campylobacter, Campylobacter j ejuni 81-176, in two murine models. The sequence of the flaA gene of strain 81-176 revealed a predicted protein which was 98.1% similar to that of VC1 67 FlaA over the region expressed in the fusion protein. Mice were immunize d intranasally with two doses of 3 to 50 mu g of MBP-FlaA, given 8 days apa rt, with or without 5 mu g of the mutant E. coli heat-labile enterotoxin (L TR192G) as a mucosal adjuvant, The full range of MBP-FlaA doses were effect ive in eliciting antigen-specific serum immunoglobulin G (IgG) responses, a nd these responses were enhanced by adjuvant use, except in the highest dos ing group. Stimulation of FlaA-specific intestinal secretory IgA (sIgA) res ponses required immunization with higher doses of MBP-FlaA (greater than or equal to 25 mu g) or coadministration of lower doses with the adjuvant, Wh en vaccinated mice were challenged intranasally 26 days after immunization, the best protection was seen in animals given 50 mu g of MBP-FlaA plus LTR 192G. The protective efficacies of this dose against disease symptoms and i ntestinal colonization were 81.1 and 84%, respectively. When mice which had been immunized with 50 mu g of MBP-FlaA plus LTR192G intranasally were cha llenged orally with 8 x 10(10), 8 x 10(9), or 8 x 10(8) cells of strain 81- 176, the protective efficacies against intestinal colonization at 7 days po stinfection were 71.4, 71.4, and 100%, respectively.