Serum sensitivity and apathogenicity for chickens and chick embryos of Escherichia coli J5 strain.

Escherichia coli J5 strain was assessed for its serum resistance and pathogenicity for both chickens and chick embryos. Pathogenicity for chickens was assessed by intravenous inoculation into three-week-old broiler chickens. Pathogenicity for chick embryos was determined by inoculation of 12-day-old chick embryos into the allantoic cavity. Chicken serum was used to determine the serum resistance status. E coli J5 strain was found to be serum-sensitive and apathogenic for chickens and chick embryos. No mortality and no gross lesions occurred in the chickens inoculated with this strain. The chick embryos inoculated with this strain remained alive. It is worth trying this strain as a live vaccine to immunize chickens against infection from different serotypes of E coli.