Genetic and Phenotypic Variation of Campylobacter jejuni NCTC11168 Caused by flhA Mutation during Laboratory Passage / 生物医学与环境科学（英文）

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.

Comparison of the Pathogenicity of Isolates of Hyperinvasive Sequence Type 7 Belonging to Serogroups A, B, C, and X / 生物医学与环境科学（英文）

Objective@#To compare the pathogenicity of isolates of sequence type 7 (ST-7) ( ) belonging to four different serogroups (A, B, C, and X).@*Methods@#Four ST-7 isolates serogrouped as A, B, C, and X and characterized by different capsule structures, were examined for their adhesion and invasion properties, and their ability to induce cytokine release and apoptosis in the host cell (the A549 cell line).@*Results@#Among the four ST-7 isolates, the serogroup A isolate possessed the strongest adhesion and invasion ability. This isolate also induced the release of the highest levels of the pro-inflammatory mediators interleukin-6, interleukin-1β, and interferon, and the highest apoptosis rate in the host cells. However, there was no significant difference in interleukin-8 and tumor necrosis factor-α secretion between the four isolates. Based on the findings, the serogroup X isolate had the weakest pathogenicity, whereas there was almost no difference in the pathogenicity of the isolates from serogroups B and C.@*Conclusions@#The differences in the capsular structure of the four isolates of ST-7 affected their pathogenic capacities. The findings also imply that the hyperinvasive ST-7 lineage may include hypoinvasive isolates.