Neutralizing Antibodies to Epstein-Barr Virus in Healthy Populations and Patients with Infectious Mononucleosis

Abstract

Sera from healthy donors and individuals with primary Epstein-Barr virus (EBV) infections were titrated for EBV-neutralizing antibodies, and the results were compared with those obtained in indirect immunofluorescence assays for antibodies to EB-viral capsid antigens (anti-VCA) and to EBV-induced early antigens (anti-EA). Sera from more than 100 healthy donors without anti-VCA failed to show neutralizing activity, whereas, with one exception, anti-VCA-positive sera from nearly 150 donors neutralized the virus. The ratios between the neutralizing and anti-VCA titers varied considerably, however, indicating that different antibodies were measured. The general correspondence with neutralizing activity explains why anti-VCA serves as a dependable indicator of immunity to infectious mononucleosis (IM). Accordingly, sera taken before infection from individuals who subsequently developed 1M or seroconverted with respect to anti-VCA antibodies without evident or significant signs of disease were devoid of neutralizing activity. Titers of anti-VCA antibody usually attained peaks early in the course of the disease (within two weeks) and subsequently declined to lower, persistent levels, whereas maximal neutralizing titers were reached in six to seven weeks and showed no significant declines thereafter. Because of their slow development, diagnostically significant increases in titers of neutralizing antibody (≥fourfold) were observed more frequently than corresponding increments in anti-VCA antibody.