title: Functional analysis of an epitope in the S2 subunit of the murine coronavirus spike protein: involvement in fusion activity.
abstract: The monoclonal antibody (MAb) 5B19.2, which has virus-neutralizing and fusion inhibition activities, binds to an epitope (S2A) consisting of nine hydrophobic amino acids in the S2 subunit of the mouse hepatitis virus (MHV) spike (S) protein. This suggests that the S2A epitope may be involved in binding the virus to the MHV receptor and/or in virus-cell fusion. Co-immunoprecipitation analyses demonstrated that while the binding of virus to the receptor was blocked by anti-S1 MAbs, it was not blocked by the S2A antiserum, indicating that S2A was not involved in receptor-binding. The S proteins prepared in this study with mutations in the S2A epitope were either fusogenic or non-fusogenic and their fusogenicity did not correlate with the hydrophobic feature of the S2A epitope. All of these wt and mutated S proteins were similarly transported onto the cell membrane independent of their fusogenicity capability. These results suggest that S2A may mediate the fusion activity of the MHV S protein during virus entry into cells.
authors.affiliation: National Institute of Neuroscience, NCNP, 4-1-1 Ogawahigashi, Kodaira, Tokyo 187-8502, Japan1.
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Taguchi
authors.affiliation: National Veterinary Assay Laboratory, 1-15-1 Tokura, Kokubunji, Tokyo 185-8511, Japan2.|National Institute of Neuroscience, NCNP, 4-1-1 Ogawahigashi, Kodaira, Tokyo 187-8502, Japan1.
authors.forename: Yohko K
authors.initials: YK
authors.lastname: Shimazaki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D000956:Antigens, Viral / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D002459:Cell Fusion; D002460:Cell Line; D000939:Epitopes / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D008969:Molecular Sequence Data; D006517:Murine hepatitis virus / Q000187:drug effects / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D009500:Neutralization Tests; D011233:Precipitin Tests; D011991:Receptors, Virus / Q000037:antagonists & inhibitors / Q000378:metabolism; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D014760:Viral Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D000956:Antigens, Viral; D000939:Epitopes; D008562:Membrane Glycoproteins; D011991:Receptors, Virus; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; D014760:Viral Fusion Proteins; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus