The protective role of epstein-barr virus (EBV) - specific cytotoxic T lymphocytes in immunocompromised hosts with EBV infection

Abstract

Epstein-Barr virus (EBV)-specific cytotoxic T lymphocytes (CTL) play protective role in the pathogenesis of EBV infection. In the present study, the EBV-specific CTL responses in healthy donors and HIV-infected patients were investigated by vaccinia-based ELISpot assay. Furthermore, the correlations between EBV viral load and CD8⁺ T cell responses against various EBV proteins were analysed. Moreover, the feasibility to established EBV-CTL from either patients or healthy controls was studied. To evaluated cell-associated EBV DNA, EBNA-1 based real-time PCR was developed. The assay showed high sensitivity (as few as 10 copies could be detected), specificity (no cross-amplification of other Herpesviruses was demonstrated) and reproducibility (inter- and intra-assay variations within a 0.5-logl0- difference range). Quantitative of EBV-DNA revealed that EBV viral load in HIV-infected patients was significantly higher than that in healthy donors (P<0.05). On the other hand, the study of EBV-specific CTL responses showed that E BNA-3 family was the I mmunodominant protein which could be recognised by both healthy donors and HIV-infected patients. Indeed, EBNA-3b was the most immunodominant followed by EBNA-3a and EBNA-3c. The number of EBV proteins recognised was lower in HIV-infected patients than in control. This study clearly confirmed the importance of EBV-specific T cell responses in controlling EBV infection. However, the detailed study involving larger sample size may be needed to elucidate the correlate of protective immunity to EBV infection.