Cellular immune response against HBV nucleocapsid antigen

一般认为，HLA I类限制性细胞毒性T淋巴细胞（CTL）在急慢性HBV感染时肝细胞损伤中起重要作用。最近的研究也表明，B型肝炎病毒（HBV）的核心区可能是一个免疫靶点。我们用五种合成肽从慢性HBV感染患者的外周血单个核细胞（PBMC）或肝脏浸润淋巴细胞（LIL）中建立了HBcAg特异性CTL。PBMC取自10例慢性HBV感染者。5个来自PBMC的克隆和1个来自LIL的克隆显示细胞毒性应答（大于10%）。结论：慢性HBV感染者PBMC和LIL中存在识别HBcAg的HLA I类限制性CTL。在后续的研究中，我们检测了B型肝炎病毒感染前后3个时间点的部分核心区核苷酸序列的变化，并比较了氨基酸的多样性。选取6例慢性HBV携带者，进行了nt 2062-2364（303 bp）的序列测定。第二份血清的平均置换率高于第一份（6例中有4例），第三份血清的平均置换率低于第二份（6例中有4例）。HLA-A2与HLA-A2结合基序的氨基酸差异率在携带者与不携带者之间无显著性差异，虽然未发现HLA-A2特异性氨基酸替换，但某些氨基酸有高频率替换的趋势。我们正在研究HBV突变体对辅助性T淋巴细胞功能的影响。我们相信，这些结果可能会导致我们开发的疫苗治疗HBV感染。

It is generally believed that HLA class I restricted cytotoxic T lymphocytes (CTL) play an important role in hepatocellular injury during acute and chronic HBV infection. Recent studies have also suggested that hepatitis B virus (HBV) core region could be an immunological target. We established HBcAg-specific CTL from peripheral blood mononuclear cells (PBMC) or liver-infiltrating lymphocytes (LIL) of patients with chronic HBV infection using selected five synthetic peptides. PBMC were obtained from 10 patients with chronic HBV infection. Five clones from PBMC and one clone from LIL displayd a cytotoxic respones (more than 10%). We concluded that HLA class I restricted CTL that recognize HBcAg are present among PBMC and LIL of patients with chronic HBV infection. In successive study, we examined the change of nucleotide esquence of a part of core region at 3 points (before, top, and after the exacerbation) in the time course of hepatitis B infection, and compared the diversity of amino acids. 6 chronic HBV carriers who experienced the exacerbation of their disease were selected and nt 2062-2364 (303bp) were sequenced from the sera. The mean substitution rate were higher in the second sera than in the first (4 out of 6 patients), and lower in the third sera than in the second (4 out of 6patients). No significant difference was found in the rate of deduced amino acid divergence for the ideal HLA-A2 binding motifs between patients bearing HLA-A2 and not bearing it. Although no specific amino acid substitution in respect to HLA-A2 was found, some amino acid tends to be substituted at high frequency. We are now investigating the effect of HBV mutant on the function of helper T lymphocytes. We believe that these results could lead us to the developemt of vaccine therapy against HBV infection.