Immunohistochemical staining for the detection of the avian influenza virus in tissues

Immunohistochemical methods are commonly used for studying the pathogenesis of the avian influenza (AI) virus by allowing the identification of sites of replication of the virus in infected tissues and the correlation with the histopathological changes observed. In this chapter, the materials and methods for performing immunohistochemical detection of AI virus antigens in tissues are provided. The technique involves the following steps: heat-induced antigen retrieval; binding of a primary antibody to a virus type-specific antigen; antibody-antigen complex binding by a biotinylated secondary antibody; and binding of an enzyme-streptavidin conjugate. The enzyme is then visualized by application of the substrate chromogen solution to produce a colorimetric end product. Demonstration of AI virus antigen in tissues is based on chromogen deposition in the nucleus and/or cytoplasm of infected cells.