Applications of immunogold-silver enhancement: testing of monoclonal antibodies and detection of human cytomegalovirus in histologic specimens

Human cytomegalovirus (HCMV) is an important pathogen in neonates, transplant patients, and individuals with acquired immunodeficiency syndrome (AIDS). Reliable techniques for the detection of this virus in clinical specimens would aid in improving methods for diagnosis and increasing our understanding of viral pathogenesis. We evaluated the utility of immunogold-silver enhancement to determine the specificity of murine monoclonal antibodies directed against HCMV proteins and applied these antibodies to the detection of HCMV in histologic material. Nine antibodies were tested in a tissue-culture system to determine the location of staining. All were found to be active in frozen tissue, but only two of these antibodies were reactive in formalin-fixed tissue. We also evaluated a novel tissue fixative technique (AMeX; Fixation and dehydration with acetone) that has been used to maintain antigenicity of T-lymphocyte cell markers. All antibodies remained reactive against their respective HCMV proteins in tissue fixed by this technique. However, dehydration of tissue may limit the usefulness of AMeX fixation. Immunogold-silver enhancement is a useful and reliable histochemical technique for detection of HCMV antigens in pathologic specimens.