title: Antigenic modules in the N-terminal S1 region of the transmissible gastroenteritis virus spike protein.
abstract: The N-terminal S1 region of the transmissible gastroenteritis virus (TGEV) spike (S) glycoprotein contains four antigenic sites (C, B, D and A, from the N- to the C-terminal end) and is engaged in host-cell receptor recognition. The most N-terminal portion of the S1 region, which comprises antigenic sites C and B, is needed for the enteric tropism of TGEV, whereas the major antigenic site A at the C-terminal moiety is required for both respiratory and enteric cell tropism, and is engaged in recognition of the aminopeptidase N (APN) receptor. This study determined the kinetics for binding of a soluble S1 protein to the APN protein. Moreover, the S1 region of the TGEV S protein was dissected, with the aim of identifying discrete modules displaying unique antigenic sites and receptor-binding functions. Following protease treatments and mammalian cell expression methods, four modules or domains (D1-D4) were defined at the S1 region. Papain treatment identified an N-terminal domain (D1) resistant to proteolysis, whereas receptor binding defined a soluble and functional APN receptor-binding domain (D3). This domain was recognized by neutralizing antibodies belonging to the antigenic site A and therefore could be used as an immunogen for the prevention of viral infection. The organization of the four modules in the S1 region of the TGEV S glycoprotein is discussed.
authors.affiliation: Department of Macromolecule Structure, Centro Nacional de Biotecnologia, CSIC, Campus Universidad Autónoma, Darwin 3, 28049 Madrid, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Reguera
authors.affiliation: Department of Macromolecule Structure, Centro Nacional de Biotecnologia, CSIC, Campus Universidad Autónoma, Darwin 3, 28049 Madrid, Spain.
authors.forename: Desiderio
authors.initials: D
authors.lastname: Ordoño
authors.affiliation: Department of Macromolecule Structure, Centro Nacional de Biotecnologia, CSIC, Campus Universidad Autónoma, Darwin 3, 28049 Madrid, Spain.
authors.forename: César
authors.initials: C
authors.lastname: Santiago
authors.affiliation: Department of Molecular Biology, Centro Nacional de Biotecnologia, CSIC, Campus Universidad Autonoma, Darwin 3, 28049 Madrid, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Enjuanes
authors.affiliation: Department of Macromolecule Structure, Centro Nacional de Biotecnologia, CSIC, Campus Universidad Autónoma, Darwin 3, 28049 Madrid, Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Casasnovas
mesh_terms: D000818:Animals; D018826:CD13 Antigens / Q000378:metabolism*; D002460:Cell Line; D000939:Epitopes / Q000276:immunology*; D006801:Humans; D008562:Membrane Glycoproteins / Q000276:immunology* / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011991:Receptors, Virus / Q000378:metabolism*; D064370:Spike Glycoprotein, Coronavirus; D005760:Transmissible gastroenteritis virus / Q000276:immunology*; D014759:Viral Envelope Proteins / Q000276:immunology* / Q000378:metabolism
chemical_list: D000939:Epitopes; D008562:Membrane Glycoproteins; D011991:Receptors, Virus; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus; D018826:CD13 Antigens