Correlation Analysis Between Polymorphism Of VTN Gene And ETEC F4ac Resistance In Piglets

Enterotoxigenic Escherichia coli(ETEC)F4 is the main cause of post-weaning diarrhea of piglets,and the key to the pathogenesis is the recognition and adhesion of fimbriae to the receptor protein of small intestinal epithelial cells of piglets.ETEC F4 can causes many diseases,such as white scour of piglets,yellow scour of piglets and post-weaning diarrhea of piglets(PWD),and easy to mix and secondary multiple diseases.The specific binding receptor protein of ETEC F4 fimbriae is divided into three serotypes:F4ab,F4ac and F4ad,among which F4ac is the most prevalent one,and is more difficult to cure,which has brought huge economic losses to pig industry in our country.So far,the ETEC F4ac receptor protein and its causative genes have not been confirmed.Therefore,finding the genetic factors(genes or mutations)that cause the disease has become the primary goal of most breeding experts at home and abroad,which will help to explain the cause of diarrhea and produce resistant pig populations,solve the diarrhea problem of piglets and reduce the economic losses of pig industry.In this study,we used real-time fluorescence quantitative PCR method to detect the expression of VTN gene mRNA in eight tissues from three 35-day-old Large white,including heart,liver,spleen,lungs,kidneys,stomach,intestine,skeletal muscle tissues.The results showed that the VTN gene was expressed in the 8 tissues examined.The tissue with the highest expression was the small intestine,reaching 2.128,followed by the lung,reaching 1.596.The tissue with relatively low expression was heart,liver,stomach,kidney,and skeletal muscles.This study is combined of 3 breeds:Large white,Landrace and Songliao Black.The DNA ear tissues of the 3 breeds were extracted respectively for quality testing.All SNP,in porcine VTN gene exon region were analyzed by direct sequencing of PCR and PCR products,and an 8bp insertion/deletion fragment was found in exon 8 region.Further analysis was carried out on the adhesion phenotypic traits of diarrhea with enterotoxigenic Escherichia coli F4.The results showed that the 8bp insertion/deletion fragment significantly affected the adhesion of Escherichia coli F4 to piglets.It laid a foundation for the next step to develop enterotoxigenic Escherichia coli F4 resistant pig breeds by marker-assisted selection.