Abstract：Enterotoxigenic Escherichia coli (ETEC) is the main cause of Piglet early weaning diarrhea(PWED) and immunoprophylaxis is one of the most efficient measure to solve this problem. This paper aims to use E. coli F18 fimbrial adhesion F(FedF) recombinantly expressed as antigen to explore in mice(Mus musculus) the possibility of using FedF as the target to prevent PWED. Primers added with EcoRⅠand SalⅠsites were devised and synthesized according to the sequence F18 fimbriae antigen gene fedF on GenBank. Full length fedF gene fragment of 908 bp with 20 signal peptide sequence was amplified by using E. coli F18 genome as template. Then the target fragment was subcloned into the prokaryotic expression vector pET-30a (+) and the recombinant plasmid pET-fedF was transformed into E.coli BL21. After induction with IPTG, recombinant FedF about 32.9 kD was detectable. Then BALB/c mice were orally immunized by the recombinant strain E. coli [pET- fedF]. The results showed that the recombinant strain could induce high level of sera FedF specific IgG (P/N >2.0) and significant increase in intestinal sIgA by 2.07 fold (P<0.05); finally oral immunization of the recombinant strain could greatly protect mice against lethal dose of enterotoxin E. coli administration, the immune protective rate reached up to 62.5%. All the above results implied that the recombinant strain E. coli [pET- fedF] can protect mice from ETEC attach by induction of sera FedF specific IgG and intestinal sIgA, and it may be a promising weapon against PWED
