닭대장균 혈청형 O78 유래 생백신 후보주의 안전성 평가

Abstract

Chicken colibacillosis caused by infection with avian pathogenic Escherichia coli (APEC) O78 serotype can bring about prevalent economic losses and it could be ongoing concern in poultry industry. It is attempted to create a mutant strain of APEC O78 isolate, in order to attenuate the virulence of APEC O78, with a view to creating a potential candidate of live-attenuated vaccine to be used for broiler chickens. A genetic mutation in the phosphate transporter (pst ) gene was constructed in this study to lessen the virulence of the APEC O78 isolate. The resulting pst mutant of APEC O78 was verified by whole genome sequencing to see whether virulence gene profile was changed during the procedure of the pst mutation. For the safety evaluation of the pst mutant of APEC O78, a potential candidate of live-attenuated vaccine, chicken embryo lethality test was carried out with specific pathogen-free (SPF) embryonated eggs. The results from the embryo lethality test showed that the infectivity and virulence of APEC O78 pst mutant towards chicken embryo was greatly lessened enough to be used as a safe live-attenuated vaccine.