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1.
The F17 antigen from bovine enterotoxigenic Escherichia coli strain (E coli 25KHO9), which adhered to calf intestinal villi, was isolated. An enterotoxin-negative derivative (25KHO9st) was used for further studies. Using an immunogold-labeling technique, the F17 antigen was characterized as a fimbrial protein. Pure fimbriae with a subunit molecular weight of 20,000 were obtained by homogenization and use of a sucrose gradient. The adhesion of E coli 25KHO9st was mediated by the F17 fimbriae, as both F17 antibodies and F17 protein blocked the adhesion of the strain 25KHO9st. The F17 fimbriae were serologically distinct from K88, K99, F41, and 987P fimbriae and did not agglutinate bovine, ovine, guinea pig, human, or chicken erythrocytes. Peptide fingerprint analysis revealed F17 and F(Y) adhesins to be homologous, if not identical.  相似文献   

2.
采用PCR-RFLP方法检测了江苏苏太断奶仔猪FUT1基因M307位点等位基因多态性分布,在所检的49头仔猪中,GG基因型个体16头,AG基因型19头,AA基因型14头。在此基础上,制备上述不同基因型个体仔猪小肠上皮细胞,分别与表达F18ab菌毛的野生型大肠杆菌、表达F18ac菌毛含fed操纵子全基因的重组大肠杆菌和V型系统表面分泌表达F18abFedF亚单位的重组大肠杆菌进行体外黏附试验和黏附抑制试验。研究结果表明:FUT1基因M307位点中GG型和AG型仔猪小肠上皮细胞均能黏附上述3种大肠杆菌,而AA型个体小肠上皮细胞则不能黏附。将上述3种大肠杆菌分别与抗F18ab菌毛高免血清、F18ac菌毛高免血清及抗F18abFedF亚单位单因子血清作用后,则失去黏附仔猪肠上皮细胞能力。上述结果对苏太猪从体外试验上证明了FUT1基因M307位点多态性与断奶仔猪腹泻和水肿病存在着直接的相关性。  相似文献   

3.
致病性F18大肠杆菌黏附素受体易感性仔猪的体外鉴定   总被引:5,自引:0,他引:5  
在PCR-RFLP方法分析了不同猪个体FUT1基因M307位点等位基因多态性的基础上,制备M307位点为GG和AG2种类型仔猪小肠上皮细胞分别与表达F18ab菌毛的野生型大肠杆菌、表达F18ac菌毛含fed操纵子全基因的重组大肠杆菌及表面分泌表达F18ab菌毛FedF亚单位的重组大肠杆菌进行体外黏附和黏附抑制试验。结果表明,上述野生菌或重组菌对GG和AG2种基因型的30~35日龄断奶仔猪小肠上皮细胞均具有较好的黏附能力。上述3种大肠杆菌分别与抗F18ab纯菌毛血清、F18ac纯菌毛血清及抗F18ab菌毛FedF亚单位单因子血清作用后.则丢失黏附小肠上皮细胞能力。而GG基因型的3日龄仔猪小肠上皮细胞不能很好的黏附上述野生菌或重组菌.但是可以很好地黏附表达987P菌毛的大肠杆菌。  相似文献   

4.
Pyometra is a potentially life-threatening condition in bitches and is often caused by Escherichia coli infection. Both pathogenic and non-pathogenic E. coli strains commonly carry the genes for type 1 fimbriae that mediate bacterial adhesion onto host epithelium. To investigate whether the type 1 fimbrial adhesin, FimH, facilitates the binding of uropathogenic E. coli to canine endometrium, the fimH gene was insertionally inactivated in a pathogenic E. coli strain. The ability of E. coli to bind to canine endometrial epithelial cells was determined in vitro using canine uterine biopsies. Binding of the fimH mutant was only 0.3% of that of the wild type. Complementation of the mutation restored the phenotype to that of the parent. This study has developed an in vitro model that allows quantitative and qualitative assessment of bacterial binding to canine endometrium and has demonstrated that the fimH gene plays a role in adherence of pathogenic E. coli to canine endometrium.  相似文献   

5.
Fimbriae in Escherichia coli isolated from the small intestine of piglets   总被引:1,自引:0,他引:1  
Ninety E. coli strains, isolated from piglets which had died from neonatal diarrhea, were tested for the presence of K88, K99, 987P and type 1 fimbriae. Two or more types of fimbriae were demonstrated in 14 of the strains, a single fimbria! type in 44 strains while in 32 strains no fimbriae were detected. Of the 14 E. coli strains with more than 1 type of fimbriae, 12;, 10, 8 and 4 strains showed K88, K99, 987P and type 1, respectively.Twelve E. coli strains were isolated from piglets which had died in the neonatal period without showing signs of neonatal diarrhea at necropsy. One strain showed 987P and 3 strains showed type 1 fimbriae, while the remaining 8 strains were unfimbriated.Sixteen fimbriated E. coli strains were subcultured in order to examine the stability of fimbrial expression in the strains. The K88 and the type 1 fimbriae were regularly expressed, while the K99 and 987P were inconsistently demonstrated.  相似文献   

6.
以产志贺毒素样大肠杆菌(SLTEC)F18ab血清型标准菌株107/86基因组DNA为模板,利用PCR技术成功扩增出编码F18ab完整菌毛操纵子fed基因,克隆入表达载体pBR322,经限制性内切酶酶切分析,DNA琼脂糖电泳鉴定并结合序列测定分析,构建和筛选出含fed完整基因正确插入的pBR322-fed重组质粒,将上述重组质粒转化至不含任何菌毛结构的大肠杆菌SE5000,该表达重组菌能分别与兔抗F18ab亚单位蛋白FedF高免血清、鼠抗F18ab菌毛a单因子单克隆抗体、兔抗F18ab菌毛高免血清和抗F18ab菌毛IgG抗体产生明显的凝集反应。用热抽提法分别抽提和纯化SLTEC F18ab标准株107/86和重组菌SE5000(pBR322-fed)体外表达的F18ab菌毛,纯化菌毛经SDS-PAGE电泳和考马斯亮蓝染色获单一相对分子质量约为15 000蛋白条带。Western-blotting结果表明:兔抗F18ab菌毛高免血清能特异性识别SLTEC F18ab标准株107/86和重组菌SE5000(pBR322-fed)所提纯的单一主要结构蛋白。用重组菌SE5000(pBR322-fed)进行易感仔猪小肠上皮细胞体外黏附试验和黏附抑制试验,结果表明:重组菌SE5000(pBR322-fed)和SLTEC F18ab标准株107/86一样具有较强的黏附易感仔猪小肠上皮细胞的能力,而兔抗F18ab菌毛高免血清能有效地抑制上述重组菌SE5000(pBR322-fed)和SLTEC F18ab标准株107/86对易感仔猪小肠上皮细胞的黏附结合。  相似文献   

7.
Two strains of Streptococcus bovis (A1 and A5) and one strain of Escherichia coli (0141: H28) isolated from the surface of bovine ruminal mucous epithelium were examined for adherence to isolated and cultured ruminal epithelial cells. The E. coli adhered to the target cell by means of fimbriae, which had several common properties with type 1 common fimbriae and caused mannose-sensitive haemagglutination. The A1 strain of S. bovis was devoid of fimbriae and its adherence to the epithelial surface was not inhibited by treatment with sugars or phenol-treated bacterial membrane from the same organism. It was therefore postulated that the bacterial glycocalyx of the S. bovis organisms acted as ligand. The extent of bacterial adherence depended on the state of differentiation of the target cell in both the isolated and the cultured ruminal cell systems. The receptors for both adherent bacterial species were in all probability associated with the glycocalyx of the target cells.  相似文献   

8.
The possibility of adherence of Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli or Streptococcus agalactiae to the epithelium of the mammary gland was investigated by inoculating them into this gland of mice. S. aureus, S. epidermidis and E. coli did not adhere to alveolar epithelium in suckling or non-suckling mice. S. agalactiae adhered to alveolar epithelium in non-suckling mice but adhesion was not sufficiently strong to withstand suckling. Bacterial adherence probably does not play a significant role in the establishment of mastitis by these organisms.  相似文献   

9.
Enterotoxigenic colibacillosis was experimentally produced in four colostrum-deprived calves given 10(10) Escherichia coli strain 210 (serotype 09+:K30+:K99-:F41-:H-) orally and the histopathological changes compared to those seen in colostrum-fed calves infected in an earlier study with strain B44 (serotype 09+:K30+:K99+:F41+:H-). Escherichia coli strain 210 caused diarrhea, atrophic villi with cuboidal epithelium, and focal accumulations of a few neutrophils in the dome villi above Peyer's patches but neither the clinical nor the histopathological changes were as pronounced as with strain B44. The extent and distribution of adherence to the mucosal surface differed between the two strains. Strain B44 adhered as a continuous layer over most of the absorptive epithelial surface of both the jejunum and ileum. Adherence of strain 210 was restricted to the ileum and the bacteria often adhered focally in "clumps" rather than as a continuous layer, especially on the distal half of the villous surface.  相似文献   

10.
Highly virulent (strain 1) and weakly virulent (strain 3) Escherichia coli were examined using immunofluorescent and electron microscopic techniques to determine their ability to express type 1 pili in the intestinal tract of 3-week-old gnotobiotic turkeys. Turkeys were necropsied on postinoculation day (PID) 1, 2, 5, 8, and 12. Nonpiliated forms of strains 1 and 3 were more numerous than piliated forms in cecal and colonic contents examined by negative staining electron microscopy. A piliated form of strain 1 was seen in intestinal contents on each PID and was more numerous in cecal contents than in colonic contents. The mucus blanket of the cecum and colon contained large numbers of bacteria, although organisms were rarely intimately associated with the intestinal epithelium. Immunofluorescent staining indicated large numbers of piliated forms of strains 1 and 3 within the mucus blanket of the cecum and colon on PID 2, 5, 8, and 12. Piliated bacteria were infrequently seen in the ileal mucus blanket. Serum antibody titers to type 1 pili increased markedly by PID 5 and persisted in turkeys inoculated with strain 1. In contrast, antibody titers in turkeys exposed to strain 3 increased gradually and varied markedly among birds at each PID. Type 1 pili may not be important for adherence of pathogenic E coli to intestinal epithelium of turkeys.  相似文献   

11.
Type 1 fimbriae from chicken pathogenic Escherichia coli strain PDI-386 (serotype O78) was purified and characterized. Because of the acid-induced autoagglutination (T. Sekizaki, Y. Nakasato, and I. Nonomura, J. Vet. Med. Sci. 54, 493-499, 1992), the fimbriae could be easily purified by repeating acid sedimentation, washing, and dissolving in buffer (pH 8.0). In electron microscopy, the purified fimbriae showed a filament of 8 nm in diameter and 10 microns in average length. The molecular mass of the protein subunit of the purified fimbriae estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was 19,000 daltons. The amino acid composition and its NH2-terminal sequence were similar to the previously described one of the Klebsiella pneumoniae type 1 fimbriae. Moreover, there was an immunological relatedness between them. These results indicated that a molecular diversity found between the fimbriae of E. coli and that of K. pneumoniae has already been existed among chicken pathogenic E. coli strains.  相似文献   

12.
An avian pathogenic Escherichia coli (APEC) strain designated SHS4, isolated from a chicken with clinical signs of swollen head syndrome (SHS), adhered to but did not invade Hep-2 and tracheal epithelial cells. The PCR amplified fimA, csgA and tsh gene sequences. It produced Ia, Ib, E1, E3, K, and B colicins, but not colicin V and aerobactin. It harboured two plasmids of 60 and 98MDa and was resistant to streptomycin and tetracycline. Conjugation with a nalidixic acid (Na) resistant K-12 recipient strain (MS101) showed that the 98MDa plasmid did not transfer, whereas transfer of the 60MDa plasmid resulted in concomitant transfer of adhesion to Hep-2 and tracheal epithelial cells, production of the colicins Ia, E1, E3, and K, and the tsh-related DNA sequence. Transposon (TnphoA) mutagenesis of strain TR4 gave rise to strain Mut23, which lost its adhesive capacities, but was still able to express the same colicins as did strain TR4. PCR was able to amplify the tsh-related DNA sequence in this strain and a molecular probe based on transposon TnphoA indicated that the transposon was inserted in the 60MDa plasmid. Based on these results, we suggest that the 60MDa plasmid have adhesion genes, which may be responsible for the initial colonization of the upper respiratory tract of chickens.  相似文献   

13.
Avian pathogenic Escherichia coli (APEC).   总被引:14,自引:0,他引:14  
Avian pathogenic Escherichia coli (APEC) cause aerosacculitis, polyserositis, septicemia and other mainly extraintestinal diseases in chickens, turkeys and other avian species. APEC are found in the intestinal microflora of healthy birds and most of the diseases associated with them are secondary to environmental and host predisposing factors. APEC isolates commonly belong to certain serogroups, O1, O2 and O78, and to a restricted number of clones. Several experimental models have been developed, permitting a more reliable evaluation of the pathogenicity of E. coli for chickens and turkeys. Hence, virulence factors identified on APEC are adhesins such as the F1 and P fimbriae, and curli, the aerobactin iron sequestering system, K1 capsule, temperature-sensitive hemagglutinin (Tsh), resistance to the bactericidal effects of serum and cytotoxic effects. Experimental infection studies have shown that the air-exchange regions of the lung and the airsacs are important sites of entry of E. coli into the bloodstream of birds during the initial stages of infection and that resistance to phagocytosis may be an important mechanism in the development of the disease. They have also demonstrated that F1 fimbriae are expressed in the respiratory tract, whereas P fimbriae are expressed in the internal organs of infected chickens. The role of these fimbrial adhesins in the development of disease is not yet, however, fully understood. The more recent use of genetic approaches for the identification of new virulence factors will greatly enhance our knowledge of APEC pathogenic mechanisms. Diagnosis of APEC infections is based on the clinical picture, lesions and isolation of E. coli. This may be strengthened by serotyping and identification of virulence factors using immunological or molecular methods such as DNA probes and PCR. Approaches for the prevention and control of APEC infections include the control of environmental contamination and environmental parameters such as humidity and ventilation. Antibiotherapy is widely used, although APEC are frequently resistant to a wide range of antibiotics. Vaccines containing killed or attenuated virulent bacteria protect against infection with the homologous strain but are less efficient against heterologous strains. Hence, vaccination for colibacillosis is not widely practised because of the large variety of serogroups involved in field outbreaks.  相似文献   

14.
The ability of Salmonella enterica serotype Enteritidis isolates to adhere to immobilized secretions of the isthmus of the laying hen was determined in an ELISA-type assay. One-third of the 56 isolates tested in the logarithmic growth phase, adhered to the isthmal secretions. Using a binding assay of the isolates to thin paraffin sections of the oviduct, we demonstrated that the receptor of the adhesion was localized inside the tubular gland cells of the isthmus. The adhesion to immobilized isthmal secretions as well as to the paraffin sections was blocked by the addition of mannose. A fimD mutant of S. Enteritidis, lacking type 1 fimbriae, did not adhere, confirming that the adhesion was mediated by type 1 fimbriae. Mannosylated glycoproteins were demonstrated in the isthmus glandular cells using confocal laser scanning microscopy by FITC-labelled Lens culinaris lectins. It is hypothesized that the binding of S. Enteritidis to isthmal secretions could play a role in the contamination of eggs through incorporation of the bacteria in the shell membranes.  相似文献   

15.
It has been shown that Escherichia coli isolates from lesions of cellulitis belong to a limited number of clonal groups distinct from those of isolates found in the environment of these birds. In this study, different in vitro methods were used to evaluate adherence properties of E. coli isolates from cellulitis lesions and environments of high- and low-cellulitis prevalence broiler flocks. One hundred isolates were tested by hemagglutination. Adherence to frozen sections of chicken skin and binding to soluble fibronectin were examined for 40 of these 100 isolates by immunofluorescence and by immunocytofluorometry, respectively. Localization of bacterial adherence to skin tissues was confirmed by immunohistochemistry. It was demonstrated that O78:K80 isolates from cellulitis lesions adhered to skin sections to a much greater extent in deeper than in superficial tissue layers. A greater bacterial adherence following growth in TSB at 37 C was demonstrated for isolates from flocks with high prevalence of cellulitis than for isolates from flocks with low prevalence of cellulitis. MANOVA analysis results showed a significant difference between superficial and deep tissue layers only for one set of isolates from flocks with high prevalence of cellulitis. Hemagglutinating activity was variable among the O78:K80 isolates obtained from flocks with high prevalence of cellulitis. The results obtained for some O78:K80 isolates following growth in TSB suggest a role for type 1 fimbriae or F1 in adherence to skin sections. This was reinforced by the finding that adherence was inhibited by D-mannose. Poultry E. coli isolates that express F1 had no affinity for soluble fibronectin, although localization of the adherence in skin sections suggested a role for extracellular matrix components such as collagen and insoluble fibronectin.  相似文献   

16.
Avian pathogenic Escherichia coli strains are associated with a variety of extraintestinal poultry diseases, including airsacculitis, colisepticemia, and cellulitis. A number of E. coli serotypes are associated with these diseases, although the most prevalent serotype is O78. Fimbrial proteins expressed by these strains appear to be important virulence factors, including type 1 fimbriae, P fimbriae, and curli. We have been working to develop an effective vaccine to protect chickens against these diseases. We have previously shown that an attenuated Salmonella typhimurium strain expressing O78 lipopolysaccharide provides protection against challenge with an O78 avian pathogenic E. coli strain. In this work, we have constructed an attenuated S. typhimurium that expresses both the O78 lipopolysaccharide and E. coli-derived type 1 fimbriae. In these studies, chickens were vaccinated at day of hatch and again at 2 wk of age. Birds were challenged at 4 wk of age. We found that the vaccine candidate provided significant protection against airsacculitis as compared to untreated controls or birds vaccinated with an attenuated S. typhimurium that did not express any E. coli antigens. In a separate experiment, challenged vaccinates showed significant weight gain compared to challenged nonvaccinates. We were not able to demonstrate protection against E. coli O1 or O2 serotype challenge, nor against challenge with wild-type S. typhimurium.  相似文献   

17.
为研究禽致病性大肠杆菌强毒株E058的毒力相关基因在鸡体内、体外表达情况以及E058和尿道致病性大肠杆菌HEC4在LB和尿液中培养的表达情况,本研究分别提取E058株在SPF鸡体内及E058株和HEC4株在LB和尿液中静置培养的总RNA,与构建的DNA芯片杂交,检测和分析RNA的差异表达情况。芯片的检测结果表明:E058株在鸡体内和LB中培养差异表达基因共有9个,上调基因为5个,分别为neuC、iutA、cvaC、aes-15和iucCD;下调基因为4个,分别为aes-8、gyrB、aec-30和mdh。另外,芯片检测结果也显示E058株和HEC4株在LB和尿液中静置培养,具有相似的基因表达情况。  相似文献   

18.
Enterotoxigenic Escherichia coli (ETEC) infections result in large economic losses in the swine industry worldwide. The organism causes diarrhea by adhering to and colonizing enterocytes in the small intestines. While much progress has been made in understanding the pathogenesis of ETEC, no homologous intestinal epithelial cultures suitable for studying porcine ETEC pathogenesis have been described prior to this report. In the current study, we investigated the adherence of various porcine ETEC strains to two porcine (IPEC-1 and IPEC-J2) and one human (INT-407) small intestinal epithelial cell lines. Each cell line was assessed for its ability to support the adherence of E. coli expressing fimbrial adhesins K88ab, K88ac, K88ad, K99, F41, 987P, and F18. Wild-type ETEC expressing K88ab, K88ac, and K88ad efficiently bound to both IPEC-1 and IPEC-J2 cells. An ETEC strain expressing both K99 and F41 bound heavily to both porcine cell lines but an E. coli strain expressing only K99 bound very poorly to these cells. E. coli expressing F18 adhesin strongly bound to IPEC-1 cells but did not adhere to IPEC-J2 cells. The E. coli strains G58-1 and 711 which express no fimbrial adhesins and those that express 987P fimbriae failed to bind to either porcine cell line. Only strains B41 and K12:K99 bound in abundance to INT-407 cells. The binding of porcine ETEC to IPEC-J2, IPEC-1 and INT-407 with varying affinities, together with lack of binding of 987P ETEC and non-fimbriated E. coli strains, suggests strain-specific E. coli binding to these cell lines. These findings suggest the potential usefulness of porcine intestinal cell lines for studying ETEC pathogenesis.  相似文献   

19.
In order to test whether glycosphingolipids (GSLs) on the chicken intestinal mucosa serve as a receptor for Salmonella enterica serovar Enteritidis with fimbriae, we analyzed neutral GSLs and gangliosides from chicken intestinal mucosa and investigated the binding of bacteria to neutral GSLs and gangliosides. Four kinds of neutral GSLs, designated as N-1 to N-4 and four kinds of gangliosides, named G-1 to G-4, were identified on high-performance thin-layer chromatography (HPTLC) plates. In TLC immunostaining tests, fimbriated S. Enteritidis bound only to glucosylceramide (GlcCer) standard, N-1, GM3 standard and G-1, but neither to N-2, N-3, N-4, nor to G-2, G-3 and G-4. Further, the bacterial binding to N-1 and G-1 was completely inhibited by preincubation of bacteria with anti-S. Enteritidis fimbriae (SEF) 21 antibody, but not by anti-SEF14 antibody. These results suggest that both GlcCer (N-1) and ganglioside GM3 (G-1) on the epithelial cell surfaces of chicken intestine act as receptors for fimbriated S. Enteritidis.  相似文献   

20.
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