Major receptor-binding and neutralization determinants are located within the same domain of the transmissible gastroenteritis virus (coronavirus) spike protein.
The spike glycoprotein (S) of coronavirus, the major target for virus-neutralizing antibodies, is assumed to mediate the attachment of virions to the host cell. A 26-kilodalton fragment proteolytically cleaved from transmissible gastroenteritis virus (TGEV) S protein was previously shown to bear two adjacent antigenic sites, A and B, both defined by high-titer neutralizing antibodies. Recombinant baculoviruses expressing C-terminal truncations of the 26-kilodalton region were used to localize functionally important determinants in the S protein primary structure. Two overlapping 223- and 150-amino-acid-long products with serine 506 as a common N terminus expressed all of the site A and B epitopes and induced virus-binding antibodies. Coexpression of one of these truncated protein S derivatives with aminopeptidase N (APN), a cell surface molecule acting as a receptor for TGEV, led to the formation of a complex which could be immunoprecipitated by anti-S antibodies. These data provide evidence that major neutralization-mediating and receptor-binding determinants reside together within a domain of the S protein which behaves like an independent module. In spite of their ability to prevent S-APN interaction, the neutralizing antibodies appeared to recognize a preformed complex, thus indicating that antibody- and receptor-binding determinants should be essentially distinct. Together these findings bring new insight into the molecular mechanism of TGEV neutralization.
Godet
M
M
Unité de Virologie et Immunologie Moléculaires, Institut National de la Recherche Agronomique, Jouy-en-Josas, France.
Grosclaude
J
J
Delmas
B
B
Laude
H
H
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D017931:DNA Primers; D000939:Epitopes / Q000032:analysis; D005455:Fluorescent Antibody Technique; D005822:Genetic Vectors; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009500:Neutralization Tests; D017924:Nucleopolyhedroviruses; D016133:Polymerase Chain Reaction; D011991:Receptors, Virus / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D015183:Restriction Mapping; D064370:Spike Glycoprotein, Coronavirus; D018411:Spodoptera; D013552:Swine; D014162:Transfection; D005760:Transmissible gastroenteritis virus / Q000235:genetics / Q000378:metabolism*; D014759:Viral Envelope Proteins / Q000096:biosynthesis / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D017931:DNA Primers; D000939:Epitopes; D008562:Membrane Glycoproteins; D011991:Receptors, Virus; D011994:Recombinant Proteins; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus