ISOTYPE, SPECIFICITY, AND KINETICS OF SYSTEMIC AND MUCOSAL ANTIBODIES TO CAMPYLOBACTER-JEJUNI ANTIGENS, INCLUDING FLAGELLIN, DURING EXPERIMENTAL ORAL INFECTIONS OF CHICKENS

The immune response of chickens to Campylobacter jejuni infection was studied as a step in the search for vaccine candidates. One-day-old chicks orally challenged with C. jejuni strain 81116 showed significant increases in specific IgG, IgA, and IgM circulating antibodies, as detected by enzyme-linked immunosorbent assay (ELISA). These levels peaked at 9, 5, and 7 weeks postinfection, respectively. Maternal IgG antibodies were also detected over the first 2 weeks. Specific mucosal IgG and IgA antibody levels also increased significantly. All of the birds demonstrated a major response to the 62-kDa flagellin protein by Western blotting techniques. The immunodominance of flagellin was confirmed by ELISA using an antigen preparation from an aflagellate mutant. When overlapping recombinant polypeptide fragments of flagellin were used, epitopes detected by chicken antibodies were observed in region IV, between residues 95-340 of the protein. Thus flagellin may be a suitable candidate for a vaccine, although its role in protection must first be established.