Genetic diversity of lipooligosaccharide core biosynthesis gene clusters in Campylobacter jejuni

ObjectiveTo analyze the DNA sequence characteristics of the biosynthesis gene clusters in the lipooligosaccharide (LOS) core region of Campylobacter jejuni, and obtain the specific sequence features of the LOS types.

MethodsA total of 132 whole genome sequences of C. jejuni were selected for analyzing. OrthoMCL software was used to obtain the homology of LOS core region biosynthesis gene clusters and specific sequence of the different LOS type. PCR assay was established targeting the specific sequences of specific types of the gene clusters. According to the specific primers and the size of the amplified products, the main types of LOS were identified.

ResultsAmong the 132 strains, the DNA sequences of biosynthesis gene clusters in LOS core regions of 105 strains belonged to 14 previously identified types, and those of 27 strains belonged to 10 novel types according to DNA homology, i.e. CDC1- 10. There were a large number of polyA/T, polyG/C, insertion and deletion mutations of nucleobase in the sequences of the LOS core region biosynthesis gene clusters. Some mutations could lead to the amino acid mutations of the synthetase or transferase for the LOSs, affecting the antigenicity. The type A, B, C, and CDC8 of LOS specific DNA sequences were confirmed in 50 sequenced C. jejuni strains using the PCR assays developed in this study.

ConclusionThe 10 novel LOS types are helpful for the accurate identification of C. jejuni and explaining the antigenic diversity of LOS. The DNA sequence of LOS core biosynthesis gene clusters of C. jejuni is highly variable, and there are a large number of poly-structures and DNA sequence mutations, which is the potential cause of LOS antigenic diversity. The PCR assay for LOS typing can be used to rapidly screen five specific LOS types, but more strains are still needed for the validation.