Induction of short-term, nonspecific immunity against Escherichia coli infection in chickens is suppressed by cold stress or corticosterone treatment

Abstract

Nonspecific immunity against Escherichia coli infection in chickens was studied with white leghorn chickens, 5 weeks of age. Intravenous injection of inactivated bacteria or silver nitrate induced significant ( P < 0.05) immunity in 24h against infection with E. coli O1:K1 strain, based on viable bacterial counts in the spleen. Nonspecific immunity induced by formalin-inactivated Staphylococcus aureus cell suspension (FSA) was comparable with specific immunity induced by a specific vaccine, as determined by cumulative mortality during 7 days and the viable bacterial count in the spleen after infection. Nonspecific immunity was induced by FSA as early as 6h and lasted for less than 72h after stimulation. Treatment with cold stress or corticosterone suppressed the induction of nonspecific immunity by FSA. The results indicate that inducible nonspecific immunity against E. coli may be suppressed by stress in chickens.