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1.
《Veterinary microbiology》1997,54(2):133-144
Enterotoxigenic (ETEC) and enterotoxaemic (ETEEC) Escherichia (E.) coli that express F18 (F107) fimbriae colonize the small intestine and cause diarrhoea and/or oedema disease in weaned pigs. So far, two antigenic variants of F18 can be distinguished with a common antigenic factor designated ‘a’ and two specific factors called ‘b’ and ‘c’. In this study the existence of crosswise anti-colonization immunity between E. coli strains that express F18ab or F18ac fimbrial variants, respectively, was demonstrated. Weaned pigs of susceptible genotype with respect to susceptibility to adhesion of E. coli with fimbriae F18 were inoculated with E. coli strains 3064STM (O157:K-:H-:F18ab; resistant to streptomycin) and 8199RIF (O141ab:K-:H4:F18ac; resistant to rifampicin). The faecal shedding was compared subsequent to immunization and homologous or heterologous challenge. An enzyme-linked immunosorbent assay (ELISA) was applied to measure IgA, IgM and IgG antibodies against the F18ab and F18ac antigens in saliva, faeces, serum and intestinal wash samples. About 8 log CFU/g of the inoculated strains were found in faeces of all pigs following immunization as well as in non-immunized controls after challenge. Bacterial counts of the inoculated strains after challenge were between 2 and 5 log lower, without any difference between homologous and heterologous challenge. Intestinal colonization with fimbriated E. coli resulted in production of significantly increased levels of anti-fimbrial antibodies, especially IgA, in serum and intestinal wash samples. There were higher levels of homologous than of heterologous anti-fimbrial antibodies. Production of antibodies against F18a or against another common fimbrial antigen is probably responsible for crosswise anti-colonization immunity between E. coli strains with F18ab and F18ac fimbrial variants. Serum F18-specific IgA may be a useful indicator of a mucosal immune response directed against F18 fimbriae.  相似文献   

2.
The outcome of experimental intestinal infections with enterotoxigenic Escherichia coli (ETEC) is dependent on several factors. An important factor is adhesion of the challenge strain to the intestinal mucosa. The test for susceptibility towards ETEC adhesion has so far been made by an intestinal adhesion test made after slaughter of piglets. However, in an experimental infection study with the purpose to obtain diarrhoeic piglets, it would be an advantage to test for susceptibility prior to experimentation. The Mucin 4 gene on porcine chromosome 13 has been proposed as a candidate gene for the production of the specific ETEC F4ab/ac receptor, and a DNA marker-based test has been developed to allow genotyping for ETEC F4ab/ac resistance/susceptibility [J?rgensen, C.B., Cirera, S., Archibald, A.L., Anderson, L., Fredholm, M., Edfors-Lilja, I., 2004. Porcine polymorphisms and methods for detecting them. International application published under the patent cooperation treaty (PCT). PCT/DK2003/000807 or WO2004/048606-A2]. The aim of this study was to test an experimental model for ETEC O149:F4ac-induced diarrhoea in piglets, selected for susceptibility towards ETEC O149:F4ac adhesion prior to experimentation using a DNA marker-based test. Sixty-two healthy 25-32 days old recently weaned Danish crossbred piglets were used. All piglets were tested prior to experimentation for susceptibility or resistance towards ETEC O149:F4ac adhesion. Thirty-nine piglets, both susceptible and resistant, were oro-gastric intubated with 10(9)CFU of ETEC O149:F4ac and 23 age-matched piglets, both susceptible and resistant, were used as non-infected controls. Of susceptible piglets, challenged with ETEC O149:F4ac, 74% had ETEC O149:F4ac-associated diarrhoea first day after first challenge, which were significantly higher relatively to the resistant and challenged piglets where 20% had diarrhoea (p=0.04). This study suggests a model for experimental ETEC induced diarrhoea.  相似文献   

3.
Immunoprophylaxis of porcine oedema disease and post-weaning diarrhoea caused by strains of Escherichia coli expressing fimbriae F18 is an unsolved problem. The study was designed to examine whether vaccination with a live F18ac vaccine of unweaned pigs born to sows with F18ac antibody in the colostrum requires preformed fimbriae in the vaccine, and whether protection against the heterologous fimbrial variant F18ab is induced as well. Genetically susceptible pigs were vaccinated orally on three consecutive days, beginning 10 days before weaning with 10(11) CFU of an F18ac culture. Challenge with a dose of 10(7) CFU of E. coli F18 on three consecutive days was initiated 9 or 11 days after weaning. Eighteen pigs given the fimbriated F18ac vaccine and challenged with a strain of the homologous fimbrial variant were protected against colonization; mean faecal viable counts of the challenge strain were >3 log10 lower than those from the 17 non-vaccinated control pigs. The vaccinated pigs developed a significant rise of F18ac IgA serum antibodies. The 23 pigs which had received the non-fimbriated vaccine showed no significant protection and exhibited much lower serum F18ac IgA ELISA reactivities. Eighteen pigs vaccinated with the fimbriated F18ac and challenged with an F18ab strain had faecal viable counts nearly as high as those from 16 non-vaccinated control pigs. It is concluded that only oral vaccines having preformed fimbriae induce protection limited to the homologous fimbrial variant.  相似文献   

4.
There was a high incidence of neonatal scours in 38 litters of pigs born at Compton in a four month period during 1978. The most important cause of the disease was an enteropathogenic Escherichia coli strain which possessed the K88 antigen. The Compton herd has been bred to produce pigs of three genotypes with respect to the presence or absence of the intestinal receptor for the K88 antigen. These are homozygous dominants (SS) and heterozygotes (Ss) susceptible to infection by virulent K88-positive E coli, and homozygous recessives (ss) resistant to the disease. The highest incidence of diarrhoea was in the susceptible progeny of resistant dams and susceptible sires. There was no K88 associated diarrhoea in resistant progeny or in susceptible progeny of susceptible dams.  相似文献   

5.
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   

6.
F18(+)Escherichia coli infections causing post-weaning diarrhoea and/or oedema disease are a major cause of economic losses in pig industry. To date, no preventive strategy can protect pigs from F18(+)E. coli infections. One of the most attractive approaches to eliminate F18(+)E. coli infections is the selection for pigs that are resistant to F18(+)E. coli infections. However, this strategy was not believed to be favourable because of reports of genetic association with the stress-susceptibility gene in the Swiss Landrace. To investigate this potential association more thoroughly, 131 randomly selected Belgian hybrid pigs were genotyped for both the F18(+)E. coli resistance alleles (FUT1(A)) and the stress-susceptibility alleles (RYR1(T)) and their association was investigated by determining the linkage disequilibrium. This linkage disequilibrium (LD=-0.0149) is close to zero and does not differ significantly from 0 (likelihood ratio test chi(1)(2)=1.123, P=0.29), demonstrating no association between the FUT1(A) and RYR1(T) alleles. Furthermore, only a small fraction (4.6%) of the Belgian pigs was found to be resistant to F18(+)E. coli infections. Our results suggest that selection for F18(+)E. coli resistant pigs might be an attractive approach to prevent pigs from F18(+)E. coli infections, unlike to what has previously been postulated.  相似文献   

7.
F18(+)Escherichia coli have the ability to colonize the gut and cause oedema disease or post-weaning diarrhoea by adhering to specific F18 receptors (F18R) on the porcine epithelium. Although it is well established that a DNA polymorphism on base pair 307 of the FUT1 gene, encoding an alpha(1,2)fucosyltransferase, accounts for the F18R phenotype, the F18R nature is not elucidated yet. The aim of the present study was to investigate the correlation between the presence of H-2 histo-blood group antigens (HBGAs) or its derivative A-2 HBGAs on the porcine gut epithelium and F18(+)E. coli adherence. A significant positive correlation was found between expression of both the H-2 (r=0.586, P<0.01) and A-2 (r=0.775, P<0.01) HBGAs and F18(+)E. coli adherence after examination of 74 pigs aged from 0 to 23 weeks. The majority of the genetically resistant pigs (FUT1M307(A/A)) showed no HBGA expression (91.7%) and no F18(+)E. coli adherence (83.3%). In addition, it was found that F18R expression levels rise with increasing age during the first 3 weeks after birth and that F18R expression is maintained in older pigs (3-23 weeks old). Taken together, these data suggest that, apart from H-2 HBGAs, A-2 HBGAs might be involved in F18(+)E. coli adherence.  相似文献   

8.
Investigators have found that oxytetracycline decreases the adhesion of K88+ Escherichia coli to intestinal epithelial cells in vitro. This occurs with oxytetracycline-sensitive E coli at drug concentrations less than those required to prevent growth and with E coli that are resistant to the drug. We conducted experiments to determine whether oxytetracycline alters the disease caused by an oxytetracycline-resistant K88+ enterotoxigenic strain of E coli. Oxytetracycline-treated pigs (inoculated with K88+ E coli) did not differ from nontreated pigs in the incidence or severity of diarrhea, nor in the shedding of K88+ E coli. However, during recovery, weight gain by treated pigs was slower than that of nontreated pigs. The control pigs were not inoculated with E coli, and they remained clinically normal. Oxytetracycline-treated controls gained weight faster than nontreated controls. Some controls were genetically resistant to K88+ E coli, others were susceptible. The K88-resistant oxytetracycline-treated controls gained weight faster than the K88-susceptible oxytetracycline-treated and non-treated controls.  相似文献   

9.
OBJECTIVE: To determine whether CHEMYDERTM polymer has potential for use in the control of porcine postweaning colibacillosis (PWC). PROCEDURE: Two experiments were conducted in which 50 young pigs, either receiving CHEMYDERTM polymer in their food or not, were challenged orally with cultures of beta-haemolytic Escherichia coli immediately after weaning. Their response in terms of development of diarrhoea, and the extent of colonisation of the intestinal tract by the bacteria was monitored. In a third experiment CHEMYDERTM polymer was added to the water supply of a group of 15 pigs on a piggery where PWC was an ongoing clinical problem. The response of these pigs was compared with that of pigs vaccinated against PWC or left unmedicated. RESULTS: In both experimental infection trials the pigs receiving CHEMYDERTM polymer showed significantly reduced intestinal colonisation with the challenge strain of E coli, and, in trial 2, significantly less diarrhoea after weaning compared to pigs not receiving CHEMYDERTM polymer. In the field trial the pigs receiving CHEMYDERTM polymer had significantly less diarrhoea and required significantly less antibiotic treatment than the other two groups of pigs. CONCLUSION: CHEMYDERTM polymer has potential for use in the control of PWC.  相似文献   

10.
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   

11.
F18 fimbriated Escherichia coli are a newly described cause of postweaning diarrhea in pigs. Polyclonal rabbit antisera were raised to the antigenic variants, F18ab and F18ac, of these fimbriae and were used to develop monospecific sandwich enzyme-linked immunosorbent assays (ELISAs). The ELISAs were standardized with type cultures characterized by polymerase chain reaction techniques (PCR) and then used to conduct a study of the prevalence of F18 fimbriated E. coli in pigs in Northern Ireland. A total of 176 isolates were tested by ELISA and PCR. Eight isolates were positive for F18 by ELISA, of which 2 were shown to be false positives by PCR and one was PCR positive but ELISA negative. Of the 6 confirmed ELISA positives, all produced VT2 toxin and 3 produced ST toxin. Four positives were from serogroups O138 and O139, previously associated with porcine diarrhea.  相似文献   

12.
F18+ Escherichia coli can cause post-weaning diarrhoea and oedema disease in pigs. These diseases are responsible for substantial economic losses, but a vaccine is not available. A good knowledge of the characteristic of the fimbriae is useful for the development of a vaccine composed of the fimbrial virulence factor. F18 fimbriae are composed of the major subunit FedA and the minor subunits FedE and the adhesin FedF. In the present study monoclonal antibodies (mAbs) against FedA and FedF were produced. In addition to their diagnostic value, these mAbs revealed a weaker interaction between FedA and FedF compared to the subunit-subunit interactions in other fimbriae, like type 1 and P pili. Further experiments are needed to investigate if this weak interaction could be one of the reasons for the slow colonisation of the small intestinal mucosa by F18+ E. coli.  相似文献   

13.
The anti-colonization effect of porcine plasma powder against experimentally induced postweaning diarrhoea and oedema disease in just weaned piglets was examined. Piglets were infected with an Escherichia coli strain expressing F18ac fimbriae and producing SLTIIv- and LT-toxins. Reduced fecal excretion of the challenge strain and protection against clinical symptoms was obtained by daily supplementation of the feed with either 90 or 45 g of plasma powder. However, the piglets receiving 90 g of plasma powder a day showed diarrhoea and reduced weight gain compared to the piglets receiving 45 g of plasma powder a day. The diarrhoea was attributed to biogenic amines released from excessive protein in the diet.  相似文献   

14.
Three hundred and twenty-four strains of Escherichia coli isolated from weaned pigs with diarrhoea or oedema disease in Eastern China were screened by multiplex PCR for the presence of the gene encoding adhesin involved in diffuse adhesion I (AIDA-I). Two AIDA-I positive strains were subjected to analysis of the nucleotide sequence of the complete orfA and orfB of the AIDA gene. The AIDA-I positive E. coli isolates were also assessed for five fimbriae (F4, F5, F6, F18 and F41) by monoclonal antibodies and for toxin genes (STa, STb, LT, EAST1, Stx2e) by PCR. Twenty-one (6.5%) of the isolates possessed AIDA-I genes. Of these isolates, two carried AIDA-I genes as the only demonstrated virulence factors, and the remaining isolates carried other virulence factor genes. Comparing the AIDA-I sequence from porcine and human sources, a high homology of orfA both in porcine E. coli and human E. coli was observed. However, each orfB of the two porcine E. coli isolates was 3864 nucleotides long compared with 3861 for the E. coli 2787 orfB, and showed 96.5% homology to E. coli 2787. The data indicated (1) that AIDA-I may be an occasional virulence factor in post-weaning diarrhoea and oedema disease in pigs, (2) that it has the potential to transfer between porcine and human E. coli, and (3) that there is a genetic diversity in orfB between human and porcine E. coli.  相似文献   

15.
The presence of fimbrial adhesin F18 is frequently found in enterotoxigenic Escherichia coli (ETEC) and verotoxigenic E. coli (VTEC) strains responsible for diarrhoea and oedema disease of weaned pigs. The F18 adhesin occurs in two antigenic variants: F18ab is characteristic of VTEC while F18ac is more typical for ETEC. F18 encoding plasmids of 17 phenotypically characterized porcine E. coli isolates (10 ETEC, 6 VTEC and 1 ETEC/VTEC) were tested with a DNA probe for F18 fimbrial adhesin and with replicon probes for the RepFIa, RepFIb and for the RepFIc family of basic replicons. In all the cases, the F18 probe hybridized to only one plasmid band of size higher than 42MDa. All F18 plasmids were determined to be unireplicon plasmids belonging to the RepFIc replicon family of the F incompatibility complex. There was no difference between F18ac plasmids of ETEC and F18ab plasmids of VTEC strains in terms of replicon type or subtype. However, the size of F18ab plasmids of the VTEC strains varied between 42 and 98MDa, in contrast to F18ac plasmids of ETEC strains (constantly approximately 98MDa).  相似文献   

16.
A reproducible model of postweaning colibacillosis was obtained by controlling management and environmental variables to simulate conditions often seen at weaning. Suckling pigs were exposed briefly to starter diet at 1 week of age, weaned at 3 weeks of age, held at an ambient temperature of 20 +/- 2 C, and again given the starter diet. One day after weaning, each pig was given 10(10) colony-forming units of enterotoxigenic Escherichia coli strain M1823B (O157:K88ac:H43-LT+ STb+) in broth containing 1.2% sodium bicarbonate via stomach tube. In vitro adhesion by strain M1823B to isolated intestinal branch borders was used to test pigs for susceptibility to K88. In this model, 3 syndromes were induced in susceptible pigs: (1) peracute fatal diarrhea; (2) moderate diarrhea, weight loss, and fecal shedding of the inoculum strain; and (3) no diarrhea, weight loss, and fecal shedding of the inoculum strain. Rotavirus particles were not found in fecal specimens of pigs with diarrhea. The K88-susceptible, noninoculated control pigs remained clinically normal. It was concluded that susceptibility to adhesion by K88+ enterotoxigenic Escherichia coli was a requirement for the production of disease in this model; inoculation with rotavirus was not necessary.  相似文献   

17.
The enterotoxigenic Escherichia coli(ETEC) expressing F4 and F18 fimbriae are the two main pathogens associated with post-weaning diarrhea(PWD) in piglets. The growing global concern regarding antimicrobial resistance(AMR)has encouraged research into the development of nutritional and feeding strategies as well as vaccination protocols in order to counteract the PWD due to ETEC. A valid approach to researching effective strategies is to implement piglet in vivo challenge models with ETEC infection. Thus, the proper application and standardization of ETEC F4 and F18 challenge models represent an urgent priority. The current review provides an overview regarding the current piglet ETEC F4 and F18 challenge models; it highlights the key points for setting the challenge protocols and the most important indicators which should be included in research studies to verify the effectiveness of the ETEC challenge.Based on the current review, it is recommended that the setting of the model correctly assesses the choice and preconditioning of pigs, and the timing and dosage of the ETEC inoculation. Furthermore, the evaluation of the ETEC challenge response should include both clinical parameters(such as the occurrence of diarrhea,rectal temperature and bacterial fecal shedding) and biomarkers for the specific expression of ETEC F4/F18(such as antibody production, specific F4/F18 immunoglobulins(Igs), ETEC F4/F18 fecal enumeration and analysis of the F4/F18 receptors expression in the intestinal brush borders). On the basis of the review, the piglets' response upon F4 or F18 inoculation differed in terms of the timing and intensity of the diarrhea development, on ETEC fecal shedding and in the piglets' immunological antibody response. This information was considered to be relevant to correctly define the experimental protocol, the data recording and the sample collections. Appropriate challenge settings and evaluation of the response parameters will allow future research studies to comply with the replacement, reduction and refinement(3 R) approach, and to be able to evaluate the efficiency of a given feeding, nutritional or vaccination intervention in order to combat ETEC infection.  相似文献   

18.
Enteropathogenic Escherichia coli (EPEC) that are known to cause severe diarrhoea in children and young rabbits are well characterized, but there are few reports on the serotypes and intimin (eae) types of EPEC in weaned pigs. Based on detection of the eae gene by PCR and by DNA-hybridisation with LEE specific gene probes, 20 intestinal and 17 faecal eae(+) strains from diarrhoeal (164) and non-diarrhoeal (57) weaned pigs from 13 Hungarian farms, representing 12.8% of diarrhoeal and 14.0% of non-diarrhoeal pigs, were identified. The dominant serotype was O123:H11 (40%) among intestinal, and O108:H9 (23%) among faecal strains. The majority (85%) of the intestinal strains possessed eae-beta and 10% carried eae-gamma gene. In contrast, significantly (p<0.025) fewer faecal strains (53%) harboured the eae-beta gene, and 23% were eae-gamma positive. In vitro adhesion tests of intestinal and faecal eae(+) strains indicated adhesion of 20/37 of the strains to PK15 (porcine kidney) cells while only 3/37 strains adhered to HeLa cells. The ultrastructure of intimate bacterial attachment of representative porcine eae(+) strains to PK15 cells showed no pedestal formation, in contrast to the human EPEC (O127:H5, eae-alpha) strain. In conclusion, the data do not demonstrate a significant role for the eae(+)E. coli in porcine post-weaning diarrhoea, but provide new information on a dominant porcine serotype (O123:H11, eae-beta), and on differences of serotypes and intimin types of porcine eae(+) strains according to their site of isolation. Furthermore there was an indication that the PK15 cell line could be used as a model to study in vitro adherence of eae(+)E. coli of some human and porcine origin.  相似文献   

19.
The emigration of neutrophils from the blood of neonatal piglets into the intestinal lumen in response to a K88-positive strain of Escherichia coli was investigated. The pig herd used was of known genetic susceptibility to K88-positive E coli and had recently experienced an outbreak of neonatal diarrhoea. Neutrophil emigration depended on certain factors. Neutrophils emigrated into ligated loops in susceptible piglets sucking immune colostrum from susceptible dams but not into loops in colostrum deprived resistant piglets or piglets sucking non-immune colostrum from resistant dams. In susceptible, colostrum deprived piglets neutrophils in intestinal contents were only associated with severe lesions. Large numbers of neutrophils which appeared at several foci on the villi were observed in three of six resistant piglets that sucked immune colostrum from susceptible dams. It was concluded that neutrophil emigration into the intestinal lumen of piglets could occur in response to K88-positive E coli and resulted not from the presence or absence of the intestinal K88-receptor but from the ingestion of immune colostrum.  相似文献   

20.
A novel common colonization factor was detected in enterotoxigenic strains of Escherichia coli isolated from intestinal contents of piglets affected with postweaning diarrhoea. This factor was antigenically distinct from the previously described K88, K99, F41, 987P, CFAI, CFAII and Att25 fimbrial antigens. E. coli strains possessing this factor adhered to the pig intestinal brush borders and one strain, used in experimental infection in weanlings, colonized the intestinal epithelium and induced diarrhoea. Examination of 212 toxigenic strains of E. coli isolated from weanlings revealed the presence of the novel common colonization factor in 83 strains, belonging to serogroups O25, O108, O138, O141, O147 and O157. The antigen K88 was detected in 47 strains belonging to serogroups O8, O141, O147 and O149.  相似文献   

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