title: Antibody-induced endocytosis of viral glycoproteins and major histocompatibility complex class I on pseudorabies virus-infected monocytes.
abstract: Purified porcine monocytes, the natural carrier cells of pseudorabies virus (PrV) in the pig, were inoculated in vitro with PrV. At different time-points post-inoculation (p.i.) (from 7 to 17 h p.i.), the cells were washed and incubated with fluorescein isothiocyanate-labelled porcine PrV-specific polyclonal antibodies (IgG) at 37 degrees C. At all time-points tested p.i., 1 h of antibody incubation induced passive patching and subsequent internalization of the plasma membrane-anchored viral glycoproteins in approximately 65% of the infected monocytes. This endocytosis process is antibody-dependent, since biotinylated glycoproteins did not undergo spontaneous endocytosis. The process is fast and efficient, since only very low amounts of viral glycoproteins on the plasma membrane (7 h p.i.) and a minimal concentration of antibodies (0.04 mg IgG/ml) were needed to induce endocytosis. Experiments with PrV strains carrying deletions in the genes encoding the 11 different viral glycoproteins showed that viral glycoproteins gB and gD play a very important role in endocytosis (80% reduction with deletion mutants, P < 0.001), while the gE:gI Fc receptor complex, but not gE or gI alone, has a significant but lesser effect (45% reduction, P < 0.05). Double staining of viral glycoproteins and major histocompatibility complex class I (MHC I) showed a clear co-localization and co-endocytosis of MHC I with the viral glycoproteins, suggesting a possible role of the process in immune evasion of the virus.
authors.forename: H W
authors.initials: HW
authors.lastname: Favoreel
authors.forename: H J
authors.initials: HJ
authors.lastname: Nauwynck
authors.forename: H M
authors.initials: HM
authors.lastname: Halewyck
authors.forename: P
authors.initials: P
authors.lastname: Van Oostveldt
authors.forename: T C
authors.initials: TC
authors.lastname: Mettenleiter
authors.forename: M B
authors.initials: MB
authors.lastname: Pensaert
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology*; D002470:Cell Survival; D004705:Endocytosis; D005434:Flow Cytometry; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D011558:Herpesvirus 1, Suid / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D018613:Microscopy, Confocal; D009000:Monocytes / Q000276:immunology / Q000821:virology*; D013552:Swine; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000914:Antibodies, Viral; D006023:Glycoproteins; D015395:Histocompatibility Antigens Class I; D014759:Viral Envelope Proteins