Genomic characterization of the Guillain-Barre syndrome-associated Campylobacter jejuni ICDCCJ07001 Isolate

Abstract

Campylobacter jejuni ICDCCJ07001 (HS:41, ST2993) was isolated from a Guillain-Barré syndrome (GBS) patient during a 36-case GBS outbreak triggered by C. jejuni infections in north China in 2007. Sequence analysis revealed that the ICDCCJ07001 genome consisted of 1,664,840 base pairs (bp) and one tetracycline resistance plasmid of 44,084 bp. The GC content was 59.29% and 1,579 and 37 CDSs were identified on the chromosome and plasmid, respectively. The ICDCCJ07001 genome was compared to C. jejuni subsp. jejuni strains 81-176, 81116, NCTC11168, RM1221 and C. jejuni subsp. doylei 269.97. The length and organization of ICDCCJ07001 was similar to that of NCTC11168, 81-176 and 81-116 except that CMLP1 had a reverse orientation in strain ICDCCJ07001. Comparative genomic analyses were also carried out between GBS-associated C. jejuni strains. Thirteen common genes were present in four GBS-associated strains and 9 genes mapped to the LOS cluster and the ICDCCJ07001_pTet (44 kb) plasmid was mosaic in structure. Thirty-seven predicted CDS in ICDCCJ07001_pTet were homologous to genes present in three virulence-associated plasmids in Campylobacter: 81-176_pTet, pCC31 and 81-176_pVir. Comparative analysis of virulence loci and virulence-associated genes indicated that the LOS biosynthesis loci of ICDCCJ07001 belonged to type A, previously reported to be associated with cases of GBS. The polysaccharide capsular biosynthesis (CPS) loci and the flagella modification (FM) loci of ICDCCJ07001 were similar to corresponding sequences of strain 260.94 of similar serotype as strain ICDCCJ07001. Other virulence-associated genes including cadF, peb1, jlpA, cdt and ciaB were conserved between the C. jejuni strains examined.

Figure 1. Linear genome comparisons between C. jejuni subsp. jejuni 07001, C. jejuni 81-176, 81-116, NCTC11168, RM1221 and C. jejuni subsp. doylei 269.97.

BLASTN analyses were performed between C. jejuni 07001 and five other sequenced genomes of strains: C. jejuni subsp. jejuni 81-176 (A), 81-116 (B), NCTC11168 (C), RM1221 (D) and C. jejuni subsp. doylei 269.97 (E). The length and organization of the 07001 isolate were similar to those described for NCTC11168, 81-176 and 81-116 except for the reverse insertion of CMLP1 found in strain RM1221. Genome rearrangements were found between C. jejuni subsp. jejuni 07001 and C. jejuni subsp. doylei 269.97. Specific CDS in C. jejuni subsp. jejuni 07001 are listed in Table 3 and the homologous CDS between C. jejuni subsp. jejuni 07001 and 81-176, 81-116, NCTC11168, RM1221 and C. jejuni subsp. doylei 269.97 are summarized in the supplementary materials. Colors of the lines represent the identity of the DNA sequence between different CDS. Red, 90%–100%; green, 80%–89%; gold, 60%–79%; brown, 50%–59% and blue, 35%–49%. The arrow indicates the region of the reversed CMLP1 on the C. jejeuni 07001 chromosome.

Figure 2. Venn diagram and in silico comparison between three C. jejuni strains.

Group 1 (Campylobacteriosis outbreak strains C. jejuni 81-176 and 81-116 shared 1,380 homologous genes with strain 07001, 81-176 and 81-116. Group 2 (GBS associated strains including C. jejuni 260.94, HB93-13, and CF93-6) shared 1,383 homologous genes with C. jejuni 07001, 260.94, HB93-13 and CF93-6. Group 3 (enteritis associated strains including C. jejuni NCTC11168) shared 1,384 homologous genes with strains 07001 and NCTC11168. 1,327 homologous genes were common between all groups. 27, 13 and 18 CDS were specific to the Campylobacteriosis outbreak-associated group, GBS-associated strains and enteritis strains, respectively.

Figure 3. Homologous CDS among six Campylobacter plasmids.

Circular plots demonstrating the mosaic structure of the 07001_pTet plasmid and homologous CDS between the 07001_pTet and other Campylobacter plasmids. The tracks from the outside represent: (1) the entire 37 CDS on plasmid 07001 (dark blue), (2) homologous CDS on plasmid 81-176_pTet (blue), (3) homologous CDS on plasmid HB93-13_pTet (dark green), (4) homologous CDS on plasmid PCC31_pTet (green), and (5) 81-176_pVir (yellow). 26, 21, 24 and 2 homologous CDS were identified between 07001_pTet and 81-176_pTet, HB93-13_pTet, PCC31_pTet and 81-176_pVir.

Figure 4. PCR screening results of 33 CDS for 61 C. jejuni isolates in China.

33 selected CDS were screened by PCR using three pairs of primers designed to amplify conserved regions present in the 61 Chinese isolates. C. jejuni 07001 was taken as the positive control for PCR amplification. The red and green bars indicate positive and negative results, respectively.