Indentification And Prokaryotic Expression Of F41 Gene Of Diarrhea Enterotoxigenic Escherichia Coli In Calves From Tong Liao

Tongliao is a cattle-raising city in the Inner Mongolia.It is known as the hometown of yellow cattle.In recent years,with the increase in the number of cattle-raising,calf diarrhea has been increasing year by year,which has seriously affected the development of the cattle industry.Enterotoxigenic Escherichia coli(ETEC)is one of the major pathogens causing diarrhea in calves,which causes calves disease and has high morbidity and mortality.Therefore,the development of a safe and efficient vaccine to prevent cows mastitis is imminent.To understand the molecular biology information of diarrhea Escherichia coli strain in calves from Inner Mongolia.Investigated the incidence of E.coli in diarrhea of calves in various farms and retail households in Tongliao City from April 2015 to April 2017,isolation and characterization of calf diarrhea faecal pathogens were carried out with 16 S rRNA detection and serotypes.After identification,a total of 186 strains of pathogenic Escherichia coli were isolated,among which 0175 was a predominant serotype in Tongliao area and it contained F41 fimbriae.Fusogenic F41 virulence gene was amplified by PCR from the isolated Enterotoxigenic Escherichia coli(ETEC)and the recombinant plasmid pET-28a-F41 was constructed.The recombinant plasmid pET-28a-F41 was transformed into BL21 to express F41 protein.The immunogenicity of the protein was confirmed by Western blotting.Bioinformatics analysis showed that F41 protein was a hydrophobic protein with a theoretical isoelectric point of 5.02.The protein had no transmembrane helix region and was located outside the cell membrane.The subcellular localization of the F41 protein showed a ratio of about 0.05,which was a non-secreted protein.And the F41 protein had good antigenicity and flexibility,and the secondary and tertiary structure was predictedn.In this study,the F41 protein was successfully cloned and arecombinant plasmid was constructed.The expressed F41 protein had good immunogenicity.Relevant biological analysis provides the theoretical basis for future vaccine research.