Neutralization and fusion inhibition activities of monoclonal antibodies specific for the S1 subunit of the spike protein of neurovirulent murine coronavirus JHMV c1-2 variant.
The cleavage products of the spike (S) protein, the S1 and S2 subunits, of the highly neurovirulent murine coronavirus (MHV) JHMV c1-2 variant were identified by immunoprecipitation of virus-infected cell lysates after treatment with urea and 2-mercaptoethanol. By this method 14 monoclonal antibodies (MAbs) raised against the S protein of the c1-2 variant were revealed to react with the S1 subunit and one with the S2 subunit. These 14 MAbs were classified into the following three groups: (A) MAbs reactive to almost all MHV strains examined, (B) MAbs specific for the JHMV strain and (C) MAbs specific for a large S protein of the JHMV strain. All five MAbs classified in group B showed neutralization activity and four of them also showed fusion inhibition activity. Four of six MAbs in group C showed neutralizing activity to the c1-2 variant but not to the sp-4 variant, and most of them had no fusion inhibition activity. Western blot analyses showed that all of the MAbs, except for no. 2 in group A, failed to react with the denatured S and S1 proteins. All MAbs in groups A and C, with the exception of no. 19 in group A, reacted with the mildly denatured S proteins, whereas none of the MAbs in group B did. These results suggest that MAbs in group B recognized highly conformational epitopes which may be involved in the binding of virions to cellular receptors and the fusion activity of the virus.
Kubo
H
H
National Institute of Neuroscience, NCNP, Tokyo, Japan.
Takase-Yoden
S
S
Taguchi
F
F
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000302:isolation & purification / Q000494:pharmacology; D000956:Antigens, Viral / Q000096:biosynthesis / Q000276:immunology; D015153:Blotting, Western; D002478:Cells, Cultured; D003332:Coronaviridae / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes / Q000032:analysis; D014644:Genetic Variation; D046911:Macromolecular Substances; D008561:Membrane Fusion; D008715:Methionine / Q000378:metabolism; D051379:Mice; D008970:Molecular Weight; D009500:Neutralization Tests; D014764:Viral Proteins / Q000096:biosynthesis / Q000276:immunology* / Q000302:isolation & purification; D014774:Virulence
D000911:Antibodies, Monoclonal; D000956:Antigens, Viral; D000939:Epitopes; D046911:Macromolecular Substances; D014764:Viral Proteins; C064484:spike protein S, Transmissible gastroenteritis virus; D008715:Methionine