Study On Partly Biological Property Of An O Mixed Serotype Escherichia Coli Strain Causing Porcine Edema Disease

Colibacillosis is a very common disease of livestock diseases, often caused by the dissemination of local or small-scale outbreak, especially for large-scale pig farms, the more serious the harm, economic losses larger. Pathogenic Escherichia coli(E. coli) can cause diarrhea in piglets yellow, white diarrhea in piglets, piglet edema disease and post-weaning diarrhea, often by a wide range of pathogenic E. coli of different serotypes have a common role. Because a lot of E. coli serotypes and serotype cross-protection between the effective and bad, common case of pig farms in the event of a large number of antibiotic treatment, caused by the persistence of drug-resistant strains and widespread and difficult to eradicate pathogens. Pig and different regions of E. coli serotype popular mainly different in E. coli in the prevention of immune disease, it is difficult to take into account the diversity of its serotypes, variability, often leading to immune failure.The laboratory had isolated an O139, 142,26 E. coli in Pig Edema Disease investigate, whice is dare to see. We study the partly belbiological property of the O139, 142,26 Escherichia coli by many experiments below.Amplified shotgun applications of their O-antigen gene sequences and sequencing, the length of the sequence 11771bp. Bioinformatics methods to analyze its structure, determine the open reading frame and the type of functional genes. E. coli O139, 142,26, O26 and O142 of the O-antigen gene sequences and the O-antigen chain glycosylation structure, near the tree of analysis, structural analysis of transmembrane protein and precursor of lactose (Glc) acetyl add to speculate the mechanism analysis to explore the O139, 142,26 O-antigen gene characteristics. The results showed that E. coli O139, 142,26 O-antigen gene and E. coli O139 O-antigen gene homologous relations recently.Sensitivity experiments of E. coli O139, 142,26 and 10 common drug showed that bacteria to erythromycin and penicillin is not sensitive to ampicillin and carbenicillin, and sensitive to other seven kinds of drugs.To detect 12 kinds of possible virulence factors ST, LT, SLT-Ⅱe, SLT-Ⅰ, SLT-Ⅱ, FedA, K88, K99, 987P, F41, eaeA and irp2 for PCR. Only detected toxin SLT-Ⅱe and FedA fimbriae. At the same time, polymyxin extraction of toxins, and secretion of the toxin, toxicity and virulence deter- mination of strength of the sandwich ELISA experiments showed that the toxin identified as SLTⅡe, amount of toxin secreted 444μg/ml, toxin LD50 lethal dose for half 135.5μg, vero cell dose TCID50 for half of 1.05×10-5μg Escherichia coli O139,142,26 toxin SLTⅡe of power in the edema disease E. coli poisoning O139, and O138 edema disease similar to E. coli., half of intraperitoneal injection of viable LD50 dose for the 6.5×107CFU of mouse.Determination of the E. coli O139, 142,26 growth curve, with edema disease E. coli O138, O139 comparison revealed that the wild strains in the laboratory under the conditions of slow growth.For many serotypes of E. coli is unlikely to generate cross-protection features, from the perspective of the practical application of E. coli were prepared by O139,142,26 inactivated vaccine, through the immunogenicity and safety of the pilot test, a preliminary inspection of their ability to meet the E. coli potential as a vaccine. The results showed that E. coli O139,142,26 inactivated va- ccine produced on mouse immune protective effects, the immune serum with E. coli O139, O142, O26 agglutination happened, and antibody titers were 1:1280,1:640 and 1:640, with a good immune-derived. For the type of bacteria genetically engineered subunit vaccine and new vaccine for reference.