Antibodies to Early Antigens Induced by Epstein-Barr Virus in Infectious Mononucleosis

Abstract

Sera from 200 patients with heterophil-antibody-positive infectious mononucleosis (1M) and from 60 patients with heterophil-antibody-negative 1M-like disease were examined for antibodies to early antigens (EA) induced by Epstein-Barr virus (EBV) and for antibodies to viral capsid antigens (VCA) of EBV. Sera taken before illness from 37 patients with heterophil-antibody-positive 1M had neither anti-VCA nor anti-EA when tested at a dilution of 1:2. All patients in the acute phase of this disease had titers of anti-VCA between 1:40 and 1:640. Only 75% of these patients developed anti-EA at titers between 1:5 and 1:320. The anti-EA test nevertheless proved useful as an additional diagnostic tool, especially in heterophil-antibody-negative 1M-like disease. Anti-EA tends to reach peak titers later than anti-VCA, and it disappears again, usually within a few months. In contrast, anti-YCA persists for years at readily detectable and nearly constant levels. Thus, diagnostically significant fourfold or greater increments or declines in titers of anti-EA are observed more frequently than corresponding changes in levels of anti-YCA. Furthermore, because of the generally transitory nature of anti-EA responses, the presence of this antibody in an acute-phase serum at a titer ≧ 1:20 would denote, with few exceptions, a current primary infection.