Human hepatitis D virus-specific T cell epitopes

Abstract Hepatitis D virus (HDV) is a small, defective RNA virus that requires the hepatitis B surface antigen (HBsAg) of the hepatitis B virus (HBV) for its assembly, release, and transmission. Chronic HBV/HDV infection often has a severe clinical outcome and is difficult to treat. The important role of a robust virus-specific T cell response for natural viral control has been established for many other chronic viral infections, but the exact role of the T cell response in the control and progression of chronic HDV infection is far less clear. Several recent studies have characterized HDV-specific CD4+ and CD8+ T cell response on a peptide level. This review comprehensively summarizes all HDV-specific T cell epitopes described to date and describes our current knowledge of the role of T cells in HDV infection. While we now have better tools to study the adaptive anti-HDV-specific T cell response, further efforts are needed to define the HLA restriction of additional HDV-specific T cell epitopes, establish additional HDV-specific MHC tetramers, understand the degree of cross HDV genotype reactivity of individual epitopes and understand the correlation of the HBV and HDV-specific T cell response as well as the breadth and specificity of the intrahepatic HDV-specific T cell response.