Comparison Of WaaF Gene Of Guillain-Barré Syndrome-associated Campylobacter Jejuni Strains

Objective: To investigate the pathogenic mechanism of Campylobacter jejuni (C.jejuni) associated with Guillain-BarréSyndrome (GBS) and the phylogenic relationship of it, the waaF gene of 3 GBS-associated C.jejuni strains were sequenced, results were compared with the C.jejuni strain NCTC11168 to find the base and amino acid mutations, the change of secondary structure.Methods: Select and culture 3 GBS-associated C.jejuni strains isolated from stools of GBS patients in Hebei province, China. The 3 C.jejuni strains had been confirmed as GBS-associated by animal model test. After sequencing the genome sequences of them, each of the results were spliced and assembled into a complete sequence by the terminals overlapped each other. The 3 waaF sequences were compared with the corresponding sequence of NCTC11168 in GenBank to find the base and amino acid mutations, the change of secondary structure, and also construct phylogenic relationship with bioinformatics software, such as NCBI BLAST, SequenceAlignment, DNASTAR Editseq, MegAlign, Protean.Results: The waaF gene of 3 GBS-associated C.jejuni strains all had 960 base pairs. The alignment with the related sequence of NCTC11168 showed that there were 18 base mutations in zhanxing strains, which cause 5 amino acid mutations, in qiaoyuntao strain were 14 base mutations and 5 amino acid mutations, in lulei strain were 16 base mutations and 6 amino acid mutations. The 5 same mutation sites in waaF gene of the 3 GBS-associated C.jejuni stains were 1081162C→T, 1081273T→C, 1081630 A→T, 1081384T→C, 1081462 lulei, qiaoyuntaoT→G, zhanxingT→A, which caused 1 same amino acid mutation in the predicted protein: 185D→E, and changes in alpha regions of secondary structure. Except for this, there were 3 same base mutations between zhanxing and lulei strains: 1080974A→G, 1081226T→C, 1081129A→G, which caused 1 same amino acid change: 107 Y→H, and changes in coil of secondary structure; there were 2 same base mutations between qiaoyuntao and lulei strains: 1081773C→T, 1081808C→T, which caused 1 same amino acid change: 289 T→I. These mutations of base and amino acid may relate with the pathogenesis of GBS-associated C.jejuni strains. The phylogenic analysis demonstrated that the genetic distance between zhanxing and qiaoyuntao strains was 2.5%, zhanxing and lulei was 2.0%, qiaoyuntao and lulei was 1.7%. The genetic distance of predicted amino acid sequences between zhanxing and qiaoyuntao was 1.9%, zhanxing and lulei was 2.6%, qiaoyuntao and lulei was 2.2%.Conclusions: Compared waaF gene of 3 GBS-associated strains with NCTC11168, there is 1 same base mutation site 1081462lulei, qiaoyuntaoT→G, zhanxingT→A and corresponding amino acid mutation 185D→E, which may be related to the pathogenesis of GBS. Relation between the variations and GBS pathogenesis remains to be confirmed. The mutations found in the three C.jejuni strains establish the foundation for exploring the biological characteristics of GBS-associated C.jejuni strains and demonstrate that the GBS-associated C.jejuni strains of Hebei province have its regional features.