Antigen-dependent effects of divergent selective breeding based on natural antibodies on specific humoral immune responses in chickens.

•Chickens are selected and bred for KLH-binding natural antibody (NAb) levels.•The effect of NAb on specific antibody (SpAb) responses is investigated.•Increased and prolonged SpAb response is observed for some, but not all, antigens.•SpAb dynamics, and SpAb affinity are not influenced by NAb levels.•NAb levels for different antigens are not, or briefly influenced by immunization.