Preliminary Study Of Human Herpesvirus-6 Induction Of Regulatory T Cell Differentiation And Latent Infection Mechanism

Human herpesvirus-6 (HHV-6), originally isolated from patients with lymphoproliferative disease and immunosuppression, belongs to the beta-herpesvirinae subfamily and can be further classified into two variants, A and B. Identified as the causative agent of ES, HHV-6 is able to induce latent infection and persist indefinitely in the host with occasional reactivation. It can infect a variety of cell types in vitro and CD46 has been identified as its cellular receptor. HHV-6, as an important immunosuppressive virus, can alter the expression of key immune-activation molecules, perturb the cytokine network and suppress the funtion of the immune system. In fact, it has been found in many studies to be linked to various diseases.Regulatory T cells (Treg cells), a new T cell subset with hyporesponsive and immunoregulatory distinct funtion, include naturally occurring CD4~+CD25~+ Treg cells, T regulatory type 1 cells (Tr1 cells) and Th3 cells. Naturally occurring CD4~+CD25~+ Treg cells develop in the thymus, with its suppressive function mediated through the cell-cell contact-dependent mechanism. Trl cells produce high levels of IL-10 and low levels of or undectable IL-2, IFN- γ or IL-4 while Th3 cells produce high levels of TGF- β . Their suppressive function is mediated through the cytokines-dependent mechanism.Treg cells are thought to play an important role in the autoimmunity, transplantantion immunity and tumor immunity. Besides, an increasing body of evidence suggests that they contribute to the immunological hyporesponsiveness against virus, resulting in chronic infection. For example, HCV, EBV, CMV and chronic retrovirus can induce CD4~+ Treg...