ABSTRACT
Attachment of, and cell-cell fusion induced by, human cytomegalovirus were studied in the presence of neutralizing monospecific antibodies against antigenic domains 1 (AD-1) or 2 (AD-2) of glycoprotein B (gB, gpUL55). Efficient inhibition of the virion-mediated fusion event was consistently observed for the human AD-2-specific antibody as determined by a reporter gene activation assay based on permissive astrocytoma cells. In contrast, antibodies directed against the major neutralizing gB epitope AD-1 reduced fusion only by 20-60 %. Virus attachment via heparan sulfate was unaffected by the antibodies under the conditions used. Virus receptor binding as examined by heparin treatment of adsorbed virus was significantly reduced only if the virus had been coated with the AD-2-specific antibody. Neutralization of virus infectivity by the AD-2-specific antibody thus seems most likely to result from interference with a receptor-binding event during initial virus-host cell interaction.
Subject(s)
Antibodies, Viral/immunology , Cell Fusion , Cytomegalovirus/immunology , Epitopes/immunology , Viral Envelope Proteins/immunology , Antibodies, Monoclonal/immunology , Astrocytoma , Cytomegalovirus/pathogenicity , Humans , Neutralization Tests , Tumor Cells, CulturedABSTRACT
By alignment to the carboxy-terminal-deduced aa sequence of human cytomegalovirus glycoprotein B (gB), conserved hexameric aa motifs with putative function for localization in the inner nuclear membrane (INM) were identified in the nucleoplasmic tails of herpes simplex virus type 1 gB and of the cellular lamin B receptor. Fusion of the respective hexamers to CD8 as a reporter redirected transport of the chimeras into the INM, suggesting their functioning as modular signal motifs. Consecutive experiments showed that the three-residue motif RxR represents a consensus sequence which is sufficient for localization of the CD8 reporter in the INM.
