Objectives: Avian colibacillosis is significant threat in poultry industry. E.coli O78 is one of the most important serotypes responsible for the disease. Due to frequent administration of antibiotics, bacterial resistance is the main reason for failure in the treatment. Development of effective vaccines is one of the main approaches in combating the disease. Presence of numerous serotypes is of the main drawbacks for having a universal vaccine against this disease. Moreover, changes in the antigenic structure of the killed vaccines, also affect the efficacy of the vaccines. Therefore developing a killed vaccine with no changes in its structure, and be able to administrate via oral or mucosal routes looks promising. This study is an attempt to develop such a vaccine against avian pathogenic E.coli (APEC) using a E-lysis gene and recombinant technology. Materials & Methods: E-lysis expression plasmid (pmET32a) was designed and ordered to be synthesized by GenScript, USA. Due to Antibiotic resistance of the E.coli 078 (seed for vaccine) to Ampicillin, a marker in the construct, Ampicillin resistance gene was replaced by Gentamicine resistance gene, on pmET32a plasmid. Plasmid pmET32a was used to transform E.coli O78. The transformed bacteria was incubated at 28◦C with slow agitation until the optical density at 600 nm was between 0.3 to 0.4. The induction of E-lysis gene expression was done by increasing the temperature to 42◦C. Lysis was monitored by measurement of OD and performing viable cell count, during 6 hours of induction. Bacterial ghost construction was confirmed by scanning electron microscopy and CFU de ermination. Results & Conclusion: The plasmid (pmET32a) was used to transform a wild-type E.coli serotype O78. Production of E.coli O78 bacterial ghost in 100-250 ml liquid SOB culture was accomplished by increasing temperature up to 420C. The OD of the transformed bacteria increased during the first hour of induction and remained constant for the next 5 hours. Cell viability increased in the first hour and decreased significantly in 3 hours after induction which at this time no viable cell was found. Scanning electron microscopy showed the formation of a few pores on the bacterial cell wall which mostly were located in the pole regions. This construction would effectively stimulate both humoral and cellular immune responses. In vivo studies for evaluation of O78 bacterial ghost immunogenicity, as a homologous vaccine against avian colibacillosis, is in progress. Due to simple method for developing vaccine this technology can be also used as autogenous vaccine

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