Multiple Homology Analyses of the flaA Gene of Campylobacter Jejuni
The sequences of the flaA gene of three strains of Campylobacter jejuni and one strain of C. coli have been published to date. PCR-RFLP analyses of the flaA gene have shown enough variation of the gene to be useful for epidemiological tracking of the organism. The flagella is a potential target for vaccination. A recombinant pan-specific vaccine will require analyses to determine if any potential epitopes are conserved through the species. To add to the data the DNA sequence of the flaA gene of five strains of C. jejuni has been generated to date and compared. The DNA fragments were produced by PCR and cloned into pCR II in triplicate and sequential forward and reverse primers were used for sequencing. The sequences could be roughly grouped into two families. Within one family, two Lior serotype 5 strains had remarkable homology with the sequence published for the Lior serotype 6 strain 81116 published by Nuijten et al., each strain only varying by two base pairs. Up to 10% dis-homology was found. The greatest variation occurred between bases around 1000 to 1300 of the 1760 basepair sequence. This corresponds to the portion of the gene that encodes the predicted major antigenic epitopes. Except for the tight group mentioned above, the flaA genes were more closely related to the published sequences for flaB gene of the same strain than to the sequence from any other strain. This would suggest that crossover recombination is more probable within the strain than between strains.