Malmassari Silvina Laura, Deng Qiang, Fontaine Hélène, Houitte Dianne, Rimlinger François, Thiers Valérie, Maillere Bernard, Pol Stanislas, Michel Marie-Louise
INSERM U812, Pathogenèse des Hépatites Virales B et Immunothérapie, Paris, France.
Hepatology. 2007 May;45(5):1199-209. doi: 10.1002/hep.21594.
The hepatitis B X (HBx) protein is a crucial component in HBV infection in vivo and has been implicated in HCC. In this study, we aimed to detect and characterize peripheral HBx-specific T cells in chronically infected patients at the inactive carrier state of the disease. HBx-specific IFN-gamma-secreting T cells were found in 36 of 52 patients (69%), and 78% (28/36) of responding patients had T cells targeting epitopes in the carboxy-terminal part of HBx. IL-10 secretion after the stimulation of T cells with HBx-derived peptides was weak or undetectable. IFN-gamma-secreting T cells recognized a previously unknown immunodominant CD4+ T cell epitope, HBx 126-140 (EIRLKVFVLGGCRHK), in 86% (24 of 28) of patients. This peptide bound several HLA-DR molecules (HLA-DRB10101, HLA-DRB10401, HLA-DRB11301, and HLA-DRB50101). Its coding sequence overlaps a domain of the HBV genome encompassing the basic core promoter (BCP) region. Taking into account the selection of viral core promoter mutants during HBV infection, we found that HBV variants with BCP mutations were present in patient sera. We further demonstrated that these viral mutant sequences activated T cells specific for the immunodominant epitope only weakly, if at all. This is the first study linking BCP mutations and HBx-specific T cell responses.
Wild-type and variant peptides may represent potential tools for monitoring the HBV-specific T cell responses involved in sequence evolution during disease progression. Finally, the degenerate HLA-DR binding of this promiscuous, immunodominant peptide would make it a valuable component of vaccines for protecting large and ethnically diverse patient populations.
乙肝X（HBx）蛋白是体内乙肝病毒感染的关键成分，并与肝癌有关。在本研究中，我们旨在检测和鉴定处于疾病非活动携带者状态的慢性感染患者外周血中HBx特异性T细胞。52例患者中有36例（69%）发现了HBx特异性分泌干扰素-γ的T细胞，且78%（28/36）的反应性患者的T细胞靶向HBx羧基末端部分的表位。用HBx衍生肽刺激T细胞后，IL-10分泌较弱或无法检测到。86%（28例中的24例）患者的分泌干扰素-γ的T细胞识别出一个先前未知的免疫显性CD4+T细胞表位，即HBx 126 - 140（EIRLKVFVLGGCRHK）。该肽与几种HLA - DR分子（HLA - DRB10101、HLA - DRB10401、HLA - DRB11301和HLA - DRB50101）结合。其编码序列与乙肝病毒基因组包含基本核心启动子（BCP）区域的一个结构域重叠。考虑到乙肝病毒感染期间病毒核心启动子突变的选择，我们发现患者血清中存在具有BCP突变的乙肝病毒变体。我们进一步证明，这些病毒突变序列即使有作用，也只是微弱地激活针对免疫显性表位的T细胞。这是第一项将BCP突变与HBx特异性T细胞反应联系起来的研究。
野生型和变异肽可能是监测疾病进展过程中涉及序列进化的乙肝病毒特异性T细胞反应的潜在工具。最后，这种具有混杂性、免疫显性肽与多种HLA - DR的结合特性使其成为保护大量不同种族患者群体的疫苗的重要组成部分。
