A monoclonal antibody pool for routine immunohistochemical detection of human respiratory syncytial virus antigens in formalin-fixed, paraffin-embedded tissue.

Four monoclonal antibodies (MAbs) with specificities for epitopes on human respiratory syncytial virus (RSV) proteins preserved after formalin fixation and paraffin embedding were identified in fixed and embedded virus-infected HEp-2 cell pellets. The MAbs bound epitopes on the fusion protein, the nucleoprotein, the phosphoprotein, and the M2 protein of the virus. Following high-temperature antigen unmasking, immunohistochemical staining revealed RSV antigens in the lungs of five of seven children who died with confirmed RSV infection and in none of nine children who died for other reasons, with no evidence of RSV infection. Staining was cytoplasmic, granular, and confined to epithelial cells. Intense staining was seen at the apex of ciliated bronchial and bronchiolar epithelial cells in all five positive cases. In one case, of pneumonitis, infected pneumocytes were present in the alveoli and in several cases, CD68-positive, cytokeratin-negative alveolar macrophages stained for viral antigens. These antibodies may prove useful in studies of the pathogenesis of RSV infection.