A panel of hybridoma
antibodies that react with the surface peplomer
glycoprotein (E2) of the murine coronavirus JHM were produced to characterize major antigenic domains associated with functions related to virulence. Three groups of hybridoma
antibodies were differentiated by immunoprecipitation of lysates from JHM-infected cells. One group precipitated the virion structural
proteins gp170 and gp98 together with the intracellular form of E2, gp150. A second group reacted with gp98 and gp150, and a third group precipitated gp150 only. Competition assays with biotinylated hybridoma
antibodies allowed the definition of at least six different
epitope groups. Only those
antibodies which immunoprecipitated both gp170 and gp98 neutralized infectivity, inhibited cell fusion and protected infected rats against
acute disease. Another class of
antibodies binding to gp170 and gp98 also neutralized JHM virus, but did not inhibit fusion and did not protect against disease.
Antibodies that immunoprecipitated gp150 and gp98 revealed only weak neutralization and did not inhibit cell fusion or protect animals. Four
epitopes were defined by
antibodies that immunoprecipitated gp150, but revealed no
biological activity. These data indicate that the site responsible for cell fusion is associated with an
epitope group carried by gp170 and gp98.
Neutralizing antibodies bind to this and another
epitope. Furthermore, protection of JHM-infected rats against
acute disease requires both inhibition of cell fusion and neutralization of virus.