Hepatitis C virus inhibits CD4 T cell function via binding to Toll-like receptor 7.

Toll-like receptor 7 (TLR7) is a ssRNA receptor that activates dendritic cells and macrophages upon ssRNA binding; however, little is known of its role in CD4 T cells. We show here that hepatitis C virus (HCV) induces a dose dependent inhibition of cytokine production and expression of activation markers in CD4 T cells, which were restored by a TLR7-specific antagonist. These findings indicate that HCV induces CD4 T cell impairment via TLR7 which may contribute to failure of virus eradication, casting doubts on the use of TLR7 agonists to boost innate immunity in chronic RNA virus infections.