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Antigenic variation among murine coronaviruses: evidence for polymorphism on the peplomer glycoprotein, E2
Abstract:
A panel of 28 monoclonal antibodies (MAb) against the structural proteins of murine hepatitis virus-4, strain JHM (MHV-4) was used in three antigen binding assays to determine the extent of antigenic homology among six strains of murine coronaviruses. The antigenic determinants studied were highly conserved on the E1 glycoproteins and nucleocapsid (N) proteins of all strains tested. In contrast, antigenic polymorphism was observed among the E2 glycoproteins. Of three previously described antigenic determinants against which neutralizing antibodies are directed, only one, termed A(E2), was conserved on all strains. Antigenic site B(E2) was found only on the strongly neurotropic MHV-4 and site C(E2) was present on the virulent MHV-4 and MHV-3 (hepatotropic) strains, but absent on the weakly pathogenic MHV-A59, MHV-1 and MHV-S strains. Four non-neutralizing antibodies against at least one topographically distinct antigenic determinant, which we previously designated D(E2), gave binding patterns consistent with two distinct sites. One of these was present on all MHV strains tested and the other was present on all strains except MHV-S. These non-neutralizing antigenic sites were redesignated E(E2) and D(E2) respectively.
Insights
Murine coronavirus strains show conserved E1 glycoprotein and nucleocapsid protein antigens. However, E2 glycoprotein variations impact antibody binding and neutralization, revealing strain-specific antigenic sites.
Area of Science:
- Virology
- Immunology
- Molecular Biology
Background:
- Murine hepatitis virus (MHV) is a type of coronavirus that affects mice.
- Understanding antigenic variation among MHV strains is crucial for developing effective vaccines and diagnostics.
Purpose of the Study:
- To investigate the antigenic homology among six strains of murine coronaviruses.
- To characterize the antigenic determinants on structural proteins, particularly E1, E2 glycoproteins, and nucleocapsid (N) proteins.
Main Methods:
- Utilized a panel of 28 monoclonal antibodies (MAb) against MHV-4 structural proteins.
- Employed three antigen binding assays to compare antigenic sites across different MHV strains.
Main Results:
- E1 glycoproteins and N proteins exhibited highly conserved antigenic determinants across all tested MHV strains.
- Significant antigenic polymorphism was observed in E2 glycoproteins, with strain-specific variations.
- Only one of three neutralizing antibody sites (A(E2)) was conserved across all strains.
- Neutralizing sites B(E2) and C(E2) showed restricted distribution, correlating with neurotropism and virulence.
- Non-neutralizing sites (redesignated E(E2) and D(E2)) also displayed strain-specific patterns.
Conclusions:
- Antigenic determinants on E1 and N proteins are highly conserved in murine coronaviruses.
- E2 glycoprotein exhibits significant antigenic diversity, influencing viral pathogenicity and host immune response.
- Specific antigenic sites on E2 are associated with neurovirulence and hepatotropism, offering targets for further research.