B. Nayeri Fasaei - Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
T. Zahraei Salehi - Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
S. Salari - Department of Pathobiology, Faculty of Veterinary Medicine, University of Zabol, Zabol, Iran
M. M. Ranjbar - Department of FMD, Razi Vaccine and Serum Research Institute, Agricultural Research, Education, and Extension Organization (AREEO), Karaj, Iran
A. R. Yousefi - Department of Pathology and Experimental Animals, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran

Colibacillosis is known as a fatal bacterial disease resulting in a high level of commercial loss worldwide. This study amid to elucidate the sequence, genetic characteristics, and phylogeny of the bor gene in Escherichia coli (E. coli) strain c۱۳۷۸ (O۷۸:K۸۰) isolated from avian colibacillosis in Iran and develop a rapid and optimal polymerase chain reaction (PCR) molecular-based technique with specific primers to detect this gene in E. coli. A virulent avian E. coli (i.e., laboratory designation E. coli strain c۱۳۷۸) isolated from a chicken with systemic colibacillosis from a broiler farm in Tehran, Iran, in ۲۰۰۴ was used as a source of the bor gene. After DNA extraction, PCR method was used to amplify the bor gene. A ۶۵۸ bp fragment of the bor gene was amplified, sequenced, blasted, and phylogenetically studied. The most similar sequences to the bor gene in E. coli strain c۱۳۷۸ were E. coli APEC O۷۸, Enterobacteria phage HK۶۳۰, and Escherichia coli BW۲۹۵۲, respectively. There was a high similarity between the bor gene in E. coli bacteria with their phage and plasmid. Moreover, a high similarity was observed between the bor and iss genes (approximately ۹۲%) showing that they were homologous genes. In addition, the similarity analysis of different bacterial species, as well as their plasmid and bacteriophage, to the bor gene indicated that the highest similarity to O۷۸:K۸۰ was related to Paracoccidioides brasiliensis, Bacillus thuringiensis CT۴۳ plasmid pBMB۰۵۵۸, and Salmonella enterica subsp. enterica serovar Kentucky strain CVM۲۹۱۸۸ plasmid, respectively. Altogether, the results of the present study confirmed the presence of the bor gene in the studied isolates and clarified its sequence, phylogenetic relationship, and similarities of E. coli strain c۱۳۷۸ (O۷۸:K۸۰) isolated from avian colibacillosis.

E. coli, Colibacillosis, Avian, identification