For many of diseases mediated by bacteria or the like, the proliferation of bacteria is one of the causes of the diseases, and sometimes substances released by bacteria become the causes of the diseases. In the latter case, when the diseases are to be treated with antibodies, it is required to produce the antibodies using causative substances for the diseases as antigens. However, it is difficult to search for essential causative substances among from substances released by the bacteria. Then, an avian species is immunized with a disruption solution produced by disrupting cells of a bacterium as an antigen to produce a (polyclonal) antibody that can bind to an antigen as well as a substance secreted by the antigen and capable of accelerating the worsening of a symptom. An antibody produced using a surface protein of a virus as an antigen is expected to inhibit the infection with the virus.
