Genetic diversity of the Campylobactergenes coding immunodominant proteins

Three Campylobacter jejuni72Dz/92 genes (cjaA(ompH1), cjaC(hisJ) and cjaD(omp18)) encoding immunodominant proteins are considered to be potential chicken vaccine candidates. The presence and conservation of cjaA, cjaCand cjaDgenes among different Campylobacterclinical isolates were determined. The genes were detected in thirty Campylobacterstrains using hybridization as well as Western blot analysis. However, PCR products of the predicted size were amplified only from ten out of thirty examined strains regardless of the employed primer pair. The nucleotide sequence of the C. jejuni72Dz/92 genes was compared with the nucleotide sequences of their homologs cloned from other Campylobacterstrains as well as with the whole genome sequence of C. jejuniNCTC 11168. The examined sequences revealed 0 to 16% divergence. Strain‐dependent levels of divergence were observed. The polymorphism detected in cjaCwas mainly within the 5′ region of the gene, while the nucleotide substitutions in cjaAand cjaDare distributed uniformly along the whole genes. Most of the observed nucleotide substitutions occurred at the third base of the codons. This observation is consistent with the results of Western blot experiments.