Antibodies to Epstein-Barr Virus-Associated Nuclear Antigen in Infectious Mononucleosis

Development of antibodies to Epstein-Barr virus-associated nuclear antigen (EBNA) was studied in 72 patients with heterophil antibody-positive infectious mononucleosis. In contrast to the early response of antibodies to Epstein-Barr viral capsid antigens observed in all patients and to the D component of the Epstein-Barr virus-induced early antigens in 80% of the patients, antibodies to EBNA arose usually only one or more months after onset; in a few patients, however, these antibodies became detectable within three weeks. All patients eventually developed antibodies to EBNA. The geometric mean titer increased gradually, but even after one year it did not match that in healthy donors. After primary infections antibody to EBNA probably persists for life, since all donors with antibody to viral capsid antigen (some of them over 50 years old) showed antibody to EBNA. Conversely, no donor without antibody to viral capsid antigen had antibody to EBNA. The time of appearance of antibody to EBNA during infectious mononucleosis was unrelated to severity of illness.