Levels of antibody to EBV lytic proteins and EBNA1 by the luciferase immunoprecipitation system assay in EBV-seropositive control patients (CTRL), patients with CAEBV, and EBV-seronegative control patients. Each point represents an individual sample from an uninfected control or a person infected with EBV. Antibody titers are expressed in LU. P values were calculated with the Mann-Whitney U test. The solid horizontal lines indicate the geometric mean antibody titers in each group, and the vertical lines show the 95% confidence interval.