Genetic Characteristics of Lipooligosaccharide and Capsular Polysaccharide of Campylobacter jejuni from Different Sources in China

Objective To determine the distribution of two important virulence factors[lipooligosaccharide(LOS)and capsular polysaccharide(CPS)]in Campylobacter jejuni(C.jejuni)isolated from different sources in China and to develop a rapid screening method for Guillain–Barrésyndrome(GBS)-associated strains.Methods Whole-genome sequencing was carried out for 494 C.jejuni strains.The Ortho MCL software was used to define the LOS/CPS gene clusters.CPS genotyping was performed with serotype-specific sequence alignment using the BLAST software.Real-time Polymerase chain reaction(PCR)was developed with the unique sequences of specific CPS types.Results Nine novel and 29 previously confirmed LOS classes were identified.LOS classes A,B,and C were the most common(48.2%,238/494)among the 494 strains.Twenty-six capsular types were identified in 448 strains.HS2,HS4c,HS5/31,HS19,and HS8/17 were the most frequent CPS genotypes(58.7%,263/448).Strains of 17 CPS genotypes(strain number>5)had one or two prevalent LOS classes(P<0.05).Multiplex real-time PCR for rapid identification of HS2,HS19,and HS41 was developed and validated with strains of known serotypes.Conclusion Our results describe the genetic characteristics of the important virulence factors in C.jejuni strains in China.The multiplex real-time PCR developed in this study will facilitate enhanced surveillance of GBS-associated strains in China.

Genetic and Phenotypic Variation of Campylobacter jejuni NCTC11168 Caused by flhA Mutation during Laboratory Passage

Objective Campylobacter jejuni NCTC11168 is commonly used as a standard strain for flagellar biosynthesis research.In this report,two distinguished phenotypic isolates(CJ1Z,flhA mutant strain,lawn;CJ2S,flhA complemented strain,normal colony)appeared during laboratory passages for NCTC11168.Methods Phenotypic assessments,including motility plates,transmission electron microscopy,biofilm formation assay,autoagglutination assay,and genome re-sequencing for these two isolates(CJ1Z,flhA mutant strain;CJ2S,flhA complemented strain)were carried out in this study.Results Transmission electron microscopy revealed that the flagellum was lost in CJ1Z.Phenotypic assessments and genome sequencing of the two isolates were performed in this study.The capacity for biofilm formation,colony auto-agglutination,and isolate motility was reduced in the mutant CJ1Z.Comparative genomic analysis indicated a unique native nucleotide insertion in flhA(nt,2154)that caused the I719Y and I720Y mutations and early truncation in flhA.Conclusion FlhA has been found to influence the expression of flagella in C.jejuni.To the best of our knowledge,this is the first study to describe the function of the C-terminal of this protein.