Host cellular annexin II is associated with cytomegalovirus particles isolated from cultured human fibroblasts

A significant amount of host cellular annexin II was found to be associated with human cytomegalovirus isolated from cultured human fibroblasts (~1,160 molecules per virion). This composition was established by four different analytical approaches that included (i) Western blot (Immunoblot) analysis of gradient-purified virions with a monoclonal antibody specific for annexin II, (ii) peptide mapping and sequence analysis of virus- associated proteins and proteins dissociated from virus following EDTA treatment, (iii) electron microscopic immunocytochemistry of gradient- purified virions, and (iv) labeling of virus-associated proteins by lactoperoxidase-catalyzed radioiodination. These results indicated that annexin II was primarily localized to the viral surface, where it bound in a divalent cation-dependent manner. In functional experiments, a rabbit antiserum raised against annexin II inhibited cytomegalovirus plaque formation in human foreskin fibroblast monolayers in a concentration- dependent manner. Cumulatively, these studies demonstrate an association of host annexin II with cytomegalovirus particles and provide evidence for the involvement of this cellular protein in virus infectivity.