Avian pathogenic E. coli (APEC) is responsible for economic losses in all poultry farms. Certain virulence factors have been proposed as a means of controlling APEC infections, including some proteins to be used for vaccination. In the study we report here, one of the major virulence factors, the iss (increased serum survival) gene, from E. coli strain χ1378, isolated from poultry colibacillosis in Iran, was cloned to construct a prokaryotic expression vector, in order to analyse the Iss protein. The iss gene was successfully cloned into the pGEX-3X vector. The construct was transformed into E. coli BL21 to express the Iss protein under induction. The Iss protein was expressed as a glutathione-S-transferase (GST) fusion protein. GST::Iss
protein was sequenced by MS/MS MALDI-TOF techniques to confirm its amino acid sequence. BLAST analysis of the Iss protein showed high similarity with previously submitted sequences. Overall, it seems that the Iss protein from strain χ1378 could be used as a good antigen to vaccinate against poultry colibacillosis.
GST::Iss protein is currently being used as recombinant protein in SPF chicken models with the goal of
evaluating the immune response for APEC control. In conclusion, we constructed a prokaryotic expression
vector of the iss gene, and express and sequence the Iss protein from E. coli strain χ1378 isolated from