摘要
为了探究猪源肠外致病性大肠杆菌(extraintestinal pathogenic Escherichia coli,ExPEC)的致病机制,本研究通过小鼠感染模型筛选强毒菌株,以PU-1为强毒代表株进行全基因组测序(染色体登录号CP042246,质粒登录号CP042245)及分析,以铁摄取系统及自分泌毒素为关注点探究上述毒力因子在PU-1株中的编码情况,并构建单基因或多基因缺失株,探究摄铁系统及自分泌毒素在猪源ExPEC致病过程中的作用。结果显示:摄铁系统及自分泌毒素基因在血液定殖的细菌中不同程度上调,最高上调可达11倍;铁摄取系统相关基因缺失株fyuA-ybtQFX、ΔiroBCDEN、Δfur及ΔsitABCD_(Both)对感染小鼠的致病力与野生株相比显著减弱,在感染动物血液载菌量不同程度下降,最高下降至野生株的1/15左右;自分泌毒素相关基因缺失株Δvat及ΔcdtABC对感染小鼠的致病力与野株相比显著减弱,在感染动物血液载菌量下降至野生株的1/2左右。上述结果表明,摄铁系统FyuA-YbtQFX、IroBCDEN、SitABCD及SitABCD-Plasmid的有效组装,及空泡形成毒素Vat和Cdt-I型细胞致死膨胀毒素的成功转运对猪源ExPEC分离株PU-1的毒力有影响。本研究结果有助于更好地理解猪源ExPEC的致病机制,上述被鉴定的毒力因子可作为防控猪源ExPEC引起猪肠道外感染的潜在药物靶标,为防控猪群ExPEC感染方案的制定提供参考。
To investigate the effect of the pathogenic mechanisms of porcine extraintestinal pathogenic E.coli(ExPEC),its virulent strains were screened based on the mouse infection model,an ExPEC strain PU-1 was selected to sequence the whole genome(chromosome ID:CP042246;plasmid ID:CP04224)and subjected to a comprehensive analysis,the prevalence and genetic characteristics of the iron uptake systems and autotransporter toxins in the PU-1 strain were determined,and the deletion mutants targeting the above predicted virulence factors were constructed to explore their potential pathogenic roles.The results showed that the genes of iron uptake systems and autotransporter toxins were significantly upregulated(to as high as 11 folds approximately)during the blood infection of the PU-1 strain;the virulence of the mutantsΔfyuA-ybtQFX,ΔiroBCDEN,Δfur andΔsitABCD_(Both) was significantly decreased,compared with the wild-type strain in the infected mice,and their bacterial loads was also significant reduced in comparison with the wild-type strain in the blood of the infected animals;the virulence of the mutantsΔvat andΔcdtABC was also significantly decreased,compared with the wild-type strain in the infected mice,and their bacterial loads in the blood of the infected mice was reduced to about half of that of the wild-type strain.These results indicated that the effective assembly of the iron uptake systems FyuA-YbtQFX、IroBCDEN、SitABCD and SitABCD-Plasmid and the export of the vacuolating autotransporter toxin and the cytolethal distending toxin type I are essential for the virulence of the porcine ExPEC strain PU-1.This study helps to better understand the pathogenic mechanism of porcine ExPEC,and the identified virulence factors may serve as therapeutic targets for porcine ExPEC,providing potential strategies against porcine ExPEC infection.
作者
于勇
泮欣铭
章雅婷
任方勋
姚火春
马家乐
YU Yong;PAN Xinming;ZHANG Yating;REN Fangxun;YAO Huochun;MA Jiale(College of Veterinary Medicine/OIE Reference Laboratory for Streptococcosis suis,Nanjing Agricultural University,Nanjing 210095,China)
出处
《畜牧与兽医》
北大核心
2022年第5期113-120,共8页
Animal Husbandry & Veterinary Medicine
基金
国家自然科学基金青年项目(31802187)。
关键词
肠外致病性大肠杆菌
摄铁系统
自分泌毒素
毒力
extraintestinal pathogenic E.coli
iron uptake system
autotransporter toxin
virulence
