| Campylobacter spp. continues to be a major problem in large parts of the world, including China. It has been one of the most common causes of human bacterial gastroenteritis. The species most frequently associated with human disease are C. jejuni and C. coli.In this study, whole genome of 28 Chinese isolates of C. jejuni were sequenced and carried phylogenetic analysis with other sequenced whole genome of 10 isolates from several countries downloaded from the GenBank. We observed that the influence of geographical is not the main factor of popμlation structure for C. jejuni. However, the same serotype of the isolates clusters at the same branch of the phylogenetic tree, which indicates that the genetic-related factors of serotype may have an important influence on the popμlation.The polysaccharide capsμle (CPS) of C. jejuni is a virμlence factor linked to cell surface carbohydrate diversity which mainly determines the serotypes. Thirty-four CPS gene cluster structures have been published and some of them can be distinguished by mμltiple-PCR. Capsμlar types HS1/44c, HS2, HS4c, HS19, HS23/36c and HS41 are markers for Guillain-Barre syndrome (GBS). Alongside a crucial role for sialylatedlipooligosaccharides (LOS) of C. jejuni in GBS pathogenesis, the capsμles may contribute to GBS susceptibility. Analysis of 18 CPS loci revealed high gene content diversity and a mosaic nature of the capsμle loci, which are possibly due to gene gain/loss events, and demonstrated a high degree of conservation of genes within serotypes/serotype complexes Gene analysis of CPS biosynthesis-related revealed that the major function of those genes is sugar biosynthesis genes, suger transferase and O-methyl phosphoramidate. Our study shows that there are some relatively conservative genes (such as O-methyl phosphoramidate and hepotose biosynthesis genes in certain serotypes of capsμlar polysaccharide gene clusters). A method of mμltiple-PCR was developed to distinguish five specific serotypes and three GBS-related serotypes. Primers specific for each capsμle type were designed on the basis of paralogs or a unique DNA region of the CPS locus. The mμltiple-PCR can distinguish the eight serotypes in two PCRs with sensitivity and specificity of 100% using 31 strains of known Penner type. The mμltiple-PCR method will help to distinguish serotypes simply and rapidly.The method of mμ lti locus sequence typing (MLST) has been carried out in several countries and regions for the analysis of host attribution, but the host attribution china was not clear. In this study, the analysis of molecμ lar variance and the attribution model of 777strains of MLST in China were implemented, to clarify the source attribution in China., including 272 clinical isolates,309 chicken-source isolates,119 swine-source isolates,11 cattle-source isolates,18 goose-source isolates and 7 duck-source isolates. Alequin software is used for molecp lar variance and Structure software is used for the attribution model. Meanwhile, we also compared the Chinese isolates and 9 external countries-source isolates (3695 isolates) to verify the correlation of genetic distances among different groups and MLST.From the Results of ARLEQUIN, we observed that Chinese isolates of C. jejuni are mainly attributed to chicken-source isolates while Chinese isolates of Campylobacter coliare mainly attributed to swine-source isolates. Compared with external-source isolates, we found that Chinese isolates of C. jejuni are mainly attributed to chicken-source isolates and Zelanian cattle-source isolates. Meanwhile we found that Chinese isolates of C. coli are mainly attributed to British swine-source isolates and American chicken-source isolates. Compared with Chinese hosts and external isolates, we observed that there are some differences between Chinese host popμ lation structure and external host popμ lation structure. Our research constructs the methods for host attribution of Campylobacter and it is an important way to prevent and intervene the disease from the food chain from the chicken farm to the retail. |
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