[Virological and immunological studies on inapparent Epstein-Barr virus infection in healthy individuals: in comparison to immunosuppressed patients and patients with infectious mononucleosis].

The inapparent Epstein-Barr virus (EBV) infection status in healthy Japanese subjects was assessed for their EBV seroepidemiology, oral EBV excretion, and EBV-specific cellular immunity, in comparison with immunosuppressed patients and patients with infectious mononucleosis. The seroepidemiologic data of 1,086 healthy donors indicate that EBV infects the vast majority of young children by 2-3 years of age and the viral persistence follows in nearly all adults throughout life. EBV antibody titers were significantly higher in both early and late ages. When 35 seropositive healthy persons were monthly assessed for their oral EBV excretion during 1 year period, 25% shed the virus consistently, 50% every other time, and the remaining 25% occasionally. EBV was shed more frequently from 17 immunosuppressed patients and all times from 15 cases of infectious mononucleosis, in the acute and convalescent phases and also during 1 year after healing. There was a tendency that high frequency EBV shedders had high titer EBV in the mouth. In infected healthy persons, EBV-specific killer T cells were well functioning throughout life; however, the killer T cell activity were significantly low in immunosuppressed patients. The killer T cell activity first developed in infectious mononucleosis 1 week after the onset and reached the same level as in seropositive healthy persons, by 4 weeks. These findings indicate that EBV-specific cellular immunity plays an important role in the establishment and maintenance of the inapparent EBV infection in humans.