Cytokine induction after Epstein-Barr virus infection of peripheral T-lymphocytes in vitro

Background: Although the presence of Epstein-Barr virus (EBV) in different T-cell malignancies has been widely reported, there is very few data available for EBV infection of normal T cells. This leads to the lack of knowledge on the early events after T cell infection. Objective: Investigate the early events occurring after normal human peripheral T-cells are infected with EBV in vitro. Methods: T-cells were treated with EBV in vitro. The expression of tumor necrosis factor-alpha (TNF-alpha) mRNA were determined using reverse-transcription (RT)-PCR, and the level of TNF-alpha and interferon-gamma (IFN-gamma) in the culture supernatant were measured using ELISA. The effect of virus inactivation on cytokine induction from T-cells was also determined. Results: At the beginning of T cell infection by EBV, the expression of several lytic EBV transcripts (BALF5, BcLF1, and BLLF1) were observed using RT-PCR. This indicated the susceptibility of in vitro EBV infection and the entering lytic cycle of EBV-infected T-cells. The interactions of EBV with T-cells lead to induction of inflammatory cytokines, tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma), production from the T-cells. Inactivation of the virus by UV irradiation eliminated the TNF-alpha and IFN-gamma induction by EBV, suggesting the involvement in the expression of viral gene(s). Conclusion: This in vitro analysis demonstrated the cytokine induction by EBV after primary infection of T-cells.