Objective:To investigate clinicopathological,bacteriological and pathological aspects of an experimental infection with Yersinia pseudotuberculosis(Y.pseudotuberculosis)in hares in order to verify the efficacy of sero...Objective:To investigate clinicopathological,bacteriological and pathological aspects of an experimental infection with Yersinia pseudotuberculosis(Y.pseudotuberculosis)in hares in order to verify the efficacy of serology for the in vivo diagnosis.Moreover,the pathogenicity of two Y.pseudotuberculosis strains was investigated in order to detect potential differences.Methods:Twelve European brown hares(Lepus europaeus,Pallas)were experimentally infected per os and via conjunctival mucosae with Y.pseudotuberculosis:six subjects were infected with a strain isolated from a naturally infected hare(YpH)and six subjects with a strain isolated from a naturally infected rabbit(YpR).Two hares were used as negative controls.All animals were subjected to clinical,bacteriological and serological examinations during 9 weeks following the infection and,at the end of the control period,subjects still alive were euthanized and submitted to a complete post mortem examination.Results:All faecal samples collected during the control period were positive for bacteriological examinations and to a PCR for the inv gene of Y.pseudotuberculosis,while only one Yp H-infected hare showed a positive haemocultures.From the 2nd to the 9th week post infection(pi),serological analysis revealed specific antibodies with titers ranging from 1:10 to 1:160 in all YpH-infected and two YpR-infected subjects.All the Yp H-infected and two Yp R-infected hares scored positive for Y.pseudotuberculosis by means of bacteriological investigations.Grossly,suppurative multifocal lesions were detected in liver,spleen,kidney and sub-mandibular lymph nodes in both YpH-and YpR-infected hares and confirmed with histopathology.Pulmonary lesions were observed only in Yp H-infected subjects.Immunohistochemistry confirmed the presence of bacterial antigen in all infected animals.Conclusion:Results of this study revealed that YpH strain is more pathogenic for hares than the YpR strain;moreover the serological test performed in this study could be used for the diagnosis of pseudotuberculosis in hares,whereas post mortem diagnosis should be confirmed by means of bacteriological examination,PCR,histopathology and immunohistochemistry.展开更多
The flagella master regulatory gene flhDC of Yersinia pseudotuberculosis serotype III (YPIII) was mutated by deleting the middle region; replaced by a tetracycline resistant gene,; the subsequent mutant strain named Y...The flagella master regulatory gene flhDC of Yersinia pseudotuberculosis serotype III (YPIII) was mutated by deleting the middle region; replaced by a tetracycline resistant gene,; the subsequent mutant strain named YPIIIΔflhDC was obtained. Swimming assay showed that the swimming motility of the mutant strain was completely abolished. The promoter region of the flagella second-class regulatory gene fliA was fused with the lux box,; was conjugated with the mutant; the parent strains respectively for the first cross. LUCY assay result demonstrated that flhDC regulated the expression of fliA in YPIII as reported in E. coli. Biofilm formation of the mutant strain on abiotic; biotic surfaces was observed; quantified. The results showed that mutation of flhDC decreased biofilm formation on both abiotic; biotic surfaces,; abated the infection on Caenorhabdtis elegans. Our results suggest that mutation of the flagella master regulatory gene flhDC not only abolished the swimming motility, but also affected biofilm formation of YPIII on different surfaces. The new function of flhDC identified in this study provides a novel viewpoint for the control of bacterial biofilm formation.展开更多
文摘Objective:To investigate clinicopathological,bacteriological and pathological aspects of an experimental infection with Yersinia pseudotuberculosis(Y.pseudotuberculosis)in hares in order to verify the efficacy of serology for the in vivo diagnosis.Moreover,the pathogenicity of two Y.pseudotuberculosis strains was investigated in order to detect potential differences.Methods:Twelve European brown hares(Lepus europaeus,Pallas)were experimentally infected per os and via conjunctival mucosae with Y.pseudotuberculosis:six subjects were infected with a strain isolated from a naturally infected hare(YpH)and six subjects with a strain isolated from a naturally infected rabbit(YpR).Two hares were used as negative controls.All animals were subjected to clinical,bacteriological and serological examinations during 9 weeks following the infection and,at the end of the control period,subjects still alive were euthanized and submitted to a complete post mortem examination.Results:All faecal samples collected during the control period were positive for bacteriological examinations and to a PCR for the inv gene of Y.pseudotuberculosis,while only one Yp H-infected hare showed a positive haemocultures.From the 2nd to the 9th week post infection(pi),serological analysis revealed specific antibodies with titers ranging from 1:10 to 1:160 in all YpH-infected and two YpR-infected subjects.All the Yp H-infected and two Yp R-infected hares scored positive for Y.pseudotuberculosis by means of bacteriological investigations.Grossly,suppurative multifocal lesions were detected in liver,spleen,kidney and sub-mandibular lymph nodes in both YpH-and YpR-infected hares and confirmed with histopathology.Pulmonary lesions were observed only in Yp H-infected subjects.Immunohistochemistry confirmed the presence of bacterial antigen in all infected animals.Conclusion:Results of this study revealed that YpH strain is more pathogenic for hares than the YpR strain;moreover the serological test performed in this study could be used for the diagnosis of pseudotuberculosis in hares,whereas post mortem diagnosis should be confirmed by means of bacteriological examination,PCR,histopathology and immunohistochemistry.
基金Supported by the National Natural Science Foundation of China (Grant No. 30570020)
文摘The flagella master regulatory gene flhDC of Yersinia pseudotuberculosis serotype III (YPIII) was mutated by deleting the middle region; replaced by a tetracycline resistant gene,; the subsequent mutant strain named YPIIIΔflhDC was obtained. Swimming assay showed that the swimming motility of the mutant strain was completely abolished. The promoter region of the flagella second-class regulatory gene fliA was fused with the lux box,; was conjugated with the mutant; the parent strains respectively for the first cross. LUCY assay result demonstrated that flhDC regulated the expression of fliA in YPIII as reported in E. coli. Biofilm formation of the mutant strain on abiotic; biotic surfaces was observed; quantified. The results showed that mutation of flhDC decreased biofilm formation on both abiotic; biotic surfaces,; abated the infection on Caenorhabdtis elegans. Our results suggest that mutation of the flagella master regulatory gene flhDC not only abolished the swimming motility, but also affected biofilm formation of YPIII on different surfaces. The new function of flhDC identified in this study provides a novel viewpoint for the control of bacterial biofilm formation.
