title: Role of anti-gB and -gD antibodies in antibody-induced endocytosis of viral and cellular cell surface glycoproteins expressed on pseudorabies virus-infected monocytes.
abstract: The addition of porcine pseudorabies virus (PrV)-specific polyclonal IgG antibodies to PrV-infected monocytes induces internalization of plasma membrane-anchored viral glycoproteins and major histocompatibility complex (MHC) class I. Using PrV deletion strains, it was shown that gB and gD are essential for the process to occur. The purpose of the current study was to evaluate whether antibodies directed against single viral glycoproteins are able to induce endocytosis. It was shown that monoclonal antibodies directed against viral glycoprotein gB and gD, but not against gC and gE, are able to induce internalization of their respective ligand. Adding a combination of monoclonal antibodies against gB and gD resulted in endocytosis levels, comparable to the endocytosis levels observed when adding porcine PrV-specific polyclonal antibodies. The addition of genistein and tyrphostin 25, two inhibitors of tyrosine kinase activity, abolished endocytosis induced by monoclonal anti-gB and -gD antibodies in a concentration-dependent manner. The addition of similar concentrations of tyrphostin 1, an inactive tyrphostin, had no effect on endocytosis. It was also shown that a mixture of polyclonal, but not monoclonal, antibodies against gB and gD is able to induce cointernalization of MHC class I. This indicates that MHC class I cointernalization results from a passive catching of the molecules rather than from a specific interaction of the MHC class I molecules with one or more viral glycoproteins. In conclusion, it can be stated that antibody-induced crosslinking of gB and gD induces the activation of a tyrosine phosphorylation-dependent signal transduction pathway, leading to their endocytosis. Cointernalization of other viral glycoproteins and MHC class I is most likely caused by a passive catching of these molecules in the gB and gD aggregates.
authors.affiliation: Laboratory of Virology, University of Gent, Gent, Belgium.
authors.forename: H W
authors.initials: HW
authors.lastname: Favoreel
authors.forename: H J
authors.initials: HJ
authors.lastname: Nauwynck
authors.forename: P
authors.initials: P
authors.lastname: Van Oostveldt
authors.forename: M B
authors.initials: MB
authors.lastname: Pensaert
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology* / Q000502:physiology; D004705:Endocytosis / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology; D011558:Herpesvirus 1, Suid / Q000254:growth & development* / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000187:drug effects / Q000378:metabolism; D008024:Ligands; D008562:Membrane Glycoproteins / Q000187:drug effects* / Q000378:metabolism; D018613:Microscopy, Confocal; D009000:Monocytes / Q000187:drug effects* / Q000502:physiology / Q000821:virology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D014759:Viral Envelope Proteins / Q000276:immunology / Q000378:metabolism; D014764:Viral Proteins / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D004791:Enzyme Inhibitors; D015395:Histocompatibility Antigens Class I; D008024:Ligands; D008562:Membrane Glycoproteins; D014759:Viral Envelope Proteins; D014764:Viral Proteins; C107752:glycoprotein D, pseudorabies virus; C089580:glycoprotein E, Suid herpesvirus 1; C070915:glycoprotein gII, pseudorabies virus; D019833:Genistein; D011505:Protein-Tyrosine Kinases