title: Inhibition of mouse mammary tumor virus-induced T cell responses in vivo by antibodies to an open reading frame protein.
abstract: Minor lymphocyte stimulating (Mls) antigens specifically stimulate T cell responses that are restricted to particular T cell receptor (TCR) beta chain variable domains. The Mls phenotype is genetically controlled by an open reading frame (orf) located in the 3' long terminal repeat of mouse mammary tumor virus (MMTV); however, the mechanism of action of the orf gene product is unknown. Whereas predicted orf amino acid sequences show strong overall homology, the 20-30 COOH-terminal residues are strikingly polymorphic. This polymorphic region correlates with TCR V beta specificity. We have generated monoclonal antibodies to a synthetic peptide encompassing the 19 COOH-terminal amino acid residues of Mtv-7 orf, which encodes the Mls-1a determinant. We show here that these antibodies block Mls responses in vitro and can interfere specifically with thymic clonal deletion of Mls-1a reactive V beta 6+ T cells in neonatal mice. Furthermore, the antibodies can inhibit V beta 6+ T cell responses in vivo to an infectious MMTV that shares orf sequence homology and TCR specificity with Mtv-7. These results confirm the predicted extracellular localization of the orf COOH terminus and imply that the orf proteins of both endogenous and exogenous MMTV interact directly with TCR V beta.
authors.affiliation: Ludwig Institute for Cancer Research, Lausanne Branch, Epalinges, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Acha-Orbea
authors.forename: L
authors.initials: L
authors.lastname: Scarpellino
authors.forename: A N
authors.initials: AN
authors.lastname: Shakhov
authors.forename: W
authors.initials: W
authors.lastname: Held
authors.forename: H R
authors.initials: HR
authors.lastname: MacDonald
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D016367:Baculoviridae / Q000235:genetics; D001483:Base Sequence; D002460:Cell Line; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D007111:Immunity, Cellular; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics* / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C / Q000276:immunology; D008815:Mice, Inbred Strains; D016747:Minor Lymphocyte Stimulatory Antigens / Q000235:genetics / Q000276:immunology*; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D016366:Open Reading Frames; D010455:Peptides / Q000138:chemical synthesis / Q000276:immunology; D016133:Polymerase Chain Reaction; D011948:Receptors, Antigen, T-Cell / Q000235:genetics; D013601:T-Lymphocytes / Q000276:immunology*; D014162:Transfection
chemical_list: D000911:Antibodies, Monoclonal; D016747:Minor Lymphocyte Stimulatory Antigens; D009838:Oligodeoxyribonucleotides; D010455:Peptides; D011948:Receptors, Antigen, T-Cell; D004247:DNA