| Summary: | 碩士 === 國立中興大學 === 獸醫病理生物學研究所 === 105 === Clostridium difficile is an important human gut pathogen. After long-term antibiotic treatment and destruction of intestinal flora, C. difficile became dominant and caused symptoms such as pseudomembranous colitis. Several research discovered that pigs in Taiwan carried C. difficile, and of note, most of them belonged to ribotype (RT) 078 lineage including RT 078, 126, and 127. To investigate the gene diversity in these strains, we performed whole genome sequencing of C. difficile RT 127 strain P73, following by aligning with publicly available sequences of other strains, focusing on several virulence associated factor. We found that in pathogenicity locus, gene tcdA of P73 had approximately 700 bp deletion in A3 region, assuming that the RT 127 strains belonged to toxinotype VI. Previous studies on cdtR showed that point mutation at site 322 occurred, resulting in formation of truncated CdtR in RT 078 strains. In P73, no point mutation occurred at site 322 in cdtR, and we assumed that in contrast to the RT 078 strains, RT 127 strains might produce intact CdtR. We also looked into several adhesion-associated factors and found that the most divergent regions were cwp66 and slpA. According to phylogenetic analysis, P73 possessed the highest similarity to RT 078 strain QCD-23m63. Previous studies showed that RT 078 strains were aflagellated due to the deficiency of flagellar operon F2 region. Our study indicated that P73 possessed full length of flagellar operon. However, phenotypic analysis revealed that P73 was aflagellated and non-motile. In conclusion, this is the first study aiming at RT 127 strains using whole genome sequencing which might contribute to revealing the gene feature of this hyper-virulent family.
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