Antigenic relationships of coronaviruses detectable by plaque neutralization, competitive enzyme linked immunoabsorbent assay, and immunoprecipitation.

The antigenic relationships of mouse coronaviruses JHM and A59, human viruses OC43 and 229E, and multiple sclerosis (MS) isolates SD and SK have been investigated by plaque neutralization, competitive enzyme linked immunoabsorbent assay, and immunoprecipitation. A59, SK, or SD plaques are neutralized by antiserum prepared against homologous as well as heterologous virus. Plaque neutralization also demonstrated weak reactivity between SD or SK and mouse virus JHM but no reactivity with human coronavirus 229E. An antiserum prepared against human virus OC43 neutralized viruses SD and SK but not mouse viruses A59 or JHM. In a competitive enzyme linked immunoabsorbent assay (cELISA) the binding of antiserum prepared against MS isolate SK to bound SK antigen was inhibited to a comparable degree using OC43, SD, or A59 viral antigens. Coronavirus 229E or uninfected cell antigens did not block the binding of anti-SK serum to bound antigen. However, a cELISA utilizing OC43 as bound antigen and competing an anti-OC43 serum suggests that virus OC43 may be more closely related to SK than A59. Specific viral polypeptides that share antigenic determinants have been identified by immunoprecipitation of S35 methionine labeled viral infected cell extracts. Polypeptides of similar molecular weight were precipitated from A59, SD, or SK infected cell extracts by SD, SK, OC43, or A59 antisera. Our data suggests that the mouse coronavirus A59, human coronavirus OC43, and MS isolates SD and SK contain antigenically related polypeptides of similar molecular weight.