For many diseases due to microbes or the like, proliferation of microbes themselves is a cause of a symptom. However, there were cases where a substance released by the microbes is a cause of a symptom. In such cases, when attempting to treat a disease with an antibody, it was necessary to obtain an antibody against an antigen that is a substance causing the disease. However, it was difficult to find the underlying substance causing the disease among substances released by the microbes. An antibody (polyclonal) binding to not only an antigen but also to a substance, which is secreted by the antigen and accelerates the deterioration of a symptom, is obtained by immunizing birds with a lysis solution produced from lysing microbial cells as an antigen. Further, an antibody obtained with a surface protein of a virus as an antigen is expected to inhibit an infection by a virus.對於多數由細菌等導致之疾病而言，細菌本身之繁殖為症狀之原因之一，亦存在細菌所釋放之物質為原因之情形。此種情形時，若欲利用抗體治療疾病，則需要以原本之原因物質作為抗原而獲得抗體。但是，於細菌所釋放之物質中難以找出根本性之原因物質。藉由以粉碎菌體所獲得之粉碎液作為抗原來免疫鳥類，而獲得不僅與抗原結合，亦與抗原分泌之促進症狀惡化之物質結合的抗體(多株)。又，期待以病毒之表面蛋白質作為抗原而獲得之抗體可抑制病毒之感染。
