Failure to detect heterophile antigens in Epstein-Barr virus-infected cells and to demonstrate interaction of heterophile antibodies with Epstein-Barr virus.

Serial sera from nine volunteers, injected 10 years ago with sheep erythrocytes and showing heterophile antibody responses comparable to those seen in infectious mononucleosis, were retrieved from storage and examined for antibodies to Epstein–Barr virus (EBV) related antigens. Eight of the nine volunteers had pre-existing antibodies to EBV, as determined by neutralization tests and by indirect immunofluorescence reactions with fluorescein-conjugated antibodies to human IgG, but not with anti-human IgM conjugates. The EBV-specific reactivities remained unchanged after immunization. The results indicate that: (a) EBV- or EBV antigen-containing lymphoblasts from carrier or freshly infected cultures contain no detectable heterophile antigen; (b) immunization with sheep erythrocytes does not evoke antibodies which interact with EBV or EBV-infected cells. These points are supported especially by the results obtained with the heterophile antibody-positive, anti-EBV-negative serum of one of the volunteers who subsequently sustained a primary EBV infection. It is unlikely, therefore, that immunization with heterophile antigen will induce immunity to infectious mononucleosis, apart from the fact that heterophile antibody responses are largely restricted to the IgM class.