Clinical significance of variations in levels of Epstein-Barr Virus (EBV) antigen and adaptive immune response during chronic active EBV infection in children.

Pediatric patients were recruited to analyze differences in Epstein-Barr virus (EBV) copy numbers and adaptive immune reactions in children with chronic active vs acute EBV infection (CAEBVI vs AEBVI), as well as to examine the relationship between these parameters and the pathogenesis of CAEBVI. Fluorescent qPCR was used to assess EBV-DNA levels, while ELISA, antibody affinity, flow cytometry, and heterophil agglutination (HA) assays were used to evaluate patient EBV-adaptive humoral and cellular immunity. Lastly, ELISPOT was employed to assess interferon (IFN)-γ secretory functions of EBV-specific cytotoxic T-lymphocytes (CTL) as a marker of subject EBV-specific adaptive cellular immunity. The results indicated that, compared with AEBVI patients or normal children, there was a dramatic elevation in viral copy levels, viral capsid antigen (VCA)-IgA, early antigen (EA)-IgA, and EA-IgG, but a lack of EBV nuclear antigen (EBNA)-IgG and a negative HA in CAEBVI patients (p < 0.01). These subjects also had decreased CD4(+), CD8(+) (naïve), CD8(+)CD38(+), and effective memory T-lymphocyte levels compared with AEBVI patients (p < 0.01), and decreased EBV-specific CTL function compared with normal children (p < 0.01). These results suggest that there is a disturbance in EBV antigen availability and in both the adaptive humoral and cellular immune responses in patients with CAEBVI, and that these outcomes may be associated with the chronic active re-infection process itself associated with CAEBVI.