Investigation of the Mechanism of Fulminant and Severe Hepatitis Correlated with Hepatitis B Virus Mutations

乙肝病毒感染可导致多种肝损伤，包括自限性急性肝炎、重型肝炎和慢性肝炎进展为肝硬变或急性加重为肝功能衰竭，以及无症状的慢性携带者状态。乙肝核心抗原可作为细胞毒性T淋巴细胞(CTL)的免疫靶点。为了探讨发生严重免疫攻击的原因，对整个前C区和核心区进行了测序。所有无症状健康携带者和自闭型急性肝炎患者的推定氨基酸残留量均无明显变化。相反，在所有慢性重型肝病患者和致死性肝炎患者中，均发现小片段氨基酸的聚集变化。这些数据表明，这些突变区域可能在乙肝病毒病的发病机制中发挥重要作用，这些突变与严重的肝脏损害有关。最近的研究表明，与人类I类淋巴细胞抗原(HL A)结合的内源性加工病毒多肽可被CTL识别，加工后的病毒多肽大小可达9个氨基酸。为了研究CTL识别与HLAI类分子结合的HBV多肽的机制，我们已经建立了一种利用亲和柱层析从肝细胞中分离HLAI类分子的方法。我们已经开始分析从纯化的人类白细胞抗原I类分子中洗脱出来的这些多肽。

Hepatitis B virus infection leads to a wide spectrum of liver injury, including self-limited acute hepatitis, fulminant hepatitis and chronic hepatitis with progression to cirrhosis or acute exacerbation to liver failure, as well as asymtomatic chronic carrier state. The hepatitis B core antigen could be an immunological target of cytotoxic T lymphocytes (CTL). To investigate the reason why the severe immunological attack occurs, the entire precore and core region was sequenced. No significant change in deduced amino acid residuewas noted in all the asymptomatic healthy carrires and all the self-limited acute hepatitis patients. In contrast, clustering changes in small segments of amino acids were found in all the patients with severe chronic liver disease and the fatal hepatitis cases. These data suggest that these regions with mutation may play an important role in the pathogenesis of hepatitis B viral disease, and such mutations are related to severe liver damage.Recent studies revealed that the endogenously processed viral peptides bound to the class I human lymphocyte antigen (HLA) are recognized by CTLs and the size of the processed viral peptide could be as small as 9 amino acids. To study the mechanism how CTLs recognize HBV peptides bound to HLA Class I molecules, we have already established a method to separate HLA Class I molecules from hepatocytes using an affinity colum chromatography. We have started to analyze such peptides eluted from purified HLA class I molecules.