Genome sequence of a clinical isolate of Campylobacter jejuni from Thailand

Abstract

Campylobacter jejuni CG8486, which belongs to the HS4 complex, was isolated from a patient with inflammatory diarrhea in Thailand. This strain caused a diarrheal disease in ferrets comparable to that caused by C. jejuni strain 81-176, but it was much less invasive for epithelial cells in vitro than 81-176. Complete genome sequencing of CG8486 revealed a 1.65-Mb genome that was very similar to the other two published genomes of clinical isolates of C. jejuni, the genomes of 81-176 and NCTC 11168, with a limited number of CG8486-specific genes mapping outside the hypervariable carbohydrate biosynthesis loci. These data suggest that the genes required for induction of inflammatory diarrhea are among the genes shared by CG8486 and 81-176 but that either major changes in the carbohydrate loci and/or more subtle changes in other genes may modulate virulence.

FIG. 1.

Venn diagram comparing the gene contents of C. jejuni strains CG8486, NCTC 11168, and 81-176. The gene content of 81-176 is based on the results of Hofreuter et al. (17). These estimations exclude the capsule, LOS, and flagellin posttranslational modification loci. The two genes present in both strain CG8486 and strain 81-176 are Cj8486_0771 (cju16) and Cj8486_0774 (cju20) coding for a type I R-M system (HsdM and HsdR, respectively). The eight genes unique to strain NCTC 11168 are listed in Table S2 in the supplemental material.

FIG. 2.

LOS region of CG8486. (A) Diagram of the LOS genes. Each gene name is indicated below the arrow, and the CG8486 locus tag is indicated above the arrow. The cgtA gene between neuC and neuA apparently undergoes slipped-strand mismatch repair at the site indicated by the vertical line. (B) Characterization of the LOS core of CG8486 (lane 2) by silver staining and binding to cholera toxin. The cores of 81-176 (Parker class B) (lane 1), which is a mixture of GM2 and GM3 ganglioside mimics (29), and OH4384 (lane 3), which expresses a GM1 (11) mimic, are compared. CT, cholera toxin.

FIG. 3.

Schematic representation of C. jejuni CG8486 R-M loci. Zone 4 corresponds to a type III R-M system. In the CG8486 genome this locus appears to be localized between the genes corresponding to Cj0288c and Cj0289c of NCTC 11168. Zone 6 corresponds to a type I R-M system localized between the genes corresponding to Cj0759 and Cj0760 of NCTC 11168. Zone 13 corresponds to a type I R-M system and replaces the NCTC 11168 type I R-M system located between Cj1548 and Cj1555. M. Tfase, DNA methyltransferase; Dcarb., putative 4-carboxymuconolactone decarboxylase; Trsp., putative transporter.