Immunoenzymatic Techniques for Detection of Viral Antigens in Cells and Tissue

Abstract

Since their introduction, immunoenzymatic techniques for the detection of viral antigens have served as important tools to detect, confirm, and identify viruses from direct specimen, cell culture, and tissue. In this chapter, the author reviews the developments in immunohistochemistry (IHC) techniques, with particular emphasis on antibody preparations, pretreatment antigen retrieval (AR), and state-of-the-art enzymatic signal amplification methods. The use of labeled antibodies for the detection of infectious agents in tissue was first demonstrated in 1942, with identification of pneumococcal antigens by direct fluorescent antibody in the livers and spleens of experimentally infected mice. Proper fixation of tissue prior to examination is necessary to maintain tissue architecture, preserve antigenicity, and prevent degradation. Immunohistochemistry method is independent of production of cytopathic effect (CPE) or typical viral inclusions, generates permanent preparations that can be viewed with an ordinary light microscope, and allows simultaneous evaluation of stained and unstained cells in tissue sections. Nonspecific staining due to antibody trapping around defects or edges of culture or tissue sections and endogenous peroxidase activity (e.g., neutrophils and plasma cells) in inflamed tissues or specimens can be sources of false reactivity. Detection and confirmation of cytomegalovirus (CMV) infection in tissue remains one of the most common viral indications for performance of IHC stain. The performance of IHC for detection of herpes simplex virus (HSV) from tissue is similar to that of IHC for CMV.