Abstract:

Attack experiment of Meishan piglets caused by E.coli F18 strain will attain individuals of the resistance and susceptibility to E.coli F18，which will provide good material for analyzing the molecular mechanism of the resistance to E.coli F18 by high throughput technology，and provide theoretical reference for further establishing bacterial disease model in Chinese native pig breeds.In the study，the Meishan piglets were used as model animals to test their susceptibility to E.coli F18 by challenging with the pathogens through feeding F18ab and F18ac strains，which was tested and verified by a series of experiments，such as E.coli F18 bacteria detection，bacteria counting and adhesion test of the pathogens to the epithelial cells of small intestine in vitro.The results showed that there were 3 phenotypes of severe diarrhea，mild diarrhea and normality after artificial attack experiment in Meishan piglets.The number of bacteria in the intestinal contents of diarrhea piglets was more than that of normal piglets.Moreover，the adhesion test further showed that most bacteria had adhered to the epithelial cells of the small intestine of diarrhea piglets.The result of pathological tissue section showed that the villus height of pathological intestinal mucosa became shorter，congestion phenomenon appeared in the clearance of ileum tissue，and the villus of ileum tissue mucous layer fell off.These results speculated that E.coli F18 mainly affected the integrity of small intestinal villus when it combined with intestinal epithelial cell receptors，thus E.coli F18 settled in breeding and caused diarrhea in piglets.The above test results further showed that the piglets diarrhea was indeed caused by E.coli F18 attack，and we obtained several individuals of the resistance and susceptibility to E.coli F18 in Meishan piglets，which provided effective ways and methods for obtaining basic material on the genetic mechanisms of pig bacterial diarrhea and disease-resistant breeding base group.