Comparison of Commercial Elisa for Detection of Antibodies to the Viral Capsid Antigen (VCA) of Epstein-Barr Virus (EBV)

Epstein-Barr Yirus (EBY) is the causative agent of infectious mononucleosis (1M). The virus is primarily transmitted via saliva, with seroprevalence of approximately 90% in adults (Rocchi el al., 1977; Yao etal., 1985). Primary EBY infection in infants and young children is usually asymptomatic or at least very mild. In adults, 1M is a selflimiting disease characterised by fever, pharyngitis, generalised lymphadenopathy and splenomegaly (Evans, 1976). Traditionally, the serodiagnosis of EBY infection is based on the detection of heterophile antibodies. However, at least 10% of people with acute 1M fail to produce heterophile antibody with this figure being much higher in children (Evans et al., 1975; Sumaya and Ench, 1985). A more specific method of serodiagnosis of 1M is the detection of EBY -specific antibodies that appear during primary infection. Most serodiagnostic tests are based on the detection of antibodies to the Yiral Capsid Antigen (YCA) (Weidbrauk et al., 1993; Field et al., 1995). YCA antibodies of the IgG and IgM class become detectable early in the acute phase of infection. Anti-YCA IgM levels peak about 3 weeks after the onset of clinical disease, then rapidly decline to become undetectable. In contrast, YCA IgG antibodies persist for life (Youmans et al., 1985; Nikoskelainen et al., 1975). Although the indirect immunofluorscence assay (IF A) is the standard method for detection of antiYCA antibodies, it is not without limitations. IFA is difficult to standardize, time-consuming and not convenient for large scale screening (Wiedbrauk et al., 1993). The development of enzyme-linked immunosorbent assays (ELlSAs) for specific EBY antibodies has provided a sensitive and specific method that is objective and convenient for large scale screening (Hopkins et al., 1982; Luka et al., 1984) and assays for YCA are now available commercially.