Innate defense mechanisms are aimed at quickly containing and removing infectious microorganisms and involve local stromal and immune cell activation, neutrophil recruitment and activation and the induction of host defense peptides (defensins and cathelicidins), acute phase proteins and complement activation.
The bursa of Fabricius (BF) is the acknowledged central humoural immune organ unique to birds and plays a vital role in B lymphocyte development. In addition, the unique molecular immune features of bursal-derived biological peptides involved in B cell development are rarely reported.
Natural antibodies (NAb) are an important component of the innate immune system, and fight infections as a part of the first line defence. NAb are poly-reactive and can respond non-specifically to antigens. Therefore, NAb may be a key trait when evaluating an animal's potential natural disease resistance.