The mechanism of chronicity of hepatitis B (inhibition of antigen presentation by HBX protein)

首先，在Adeno-HBx感染的Renca细胞(Balb/c小鼠同源细胞系)中证实了HBx蛋白的表达，但在Adeno-HBX0(HBx基因敲除)感染的细胞中未见表达。然后，用流式细胞仪检测感染Adeno-HBX或Adeno-HBX0(M.O.I.=0.5)2天后Renca细胞MHC-I类分子的表达。与Adeno-HBX0感染的Renca细胞相比，其在Adeno-HBX感染的Renca细胞上的表达明显受到抑制。接下来，我们试图检查HBX对体内细胞毒性淋巴细胞(CTL)反应的影响。我们每隔2周将Adeno-LacZ注射到Balb/c小鼠体内，与新鲜的Adeno-LacZ感染的树突状细胞体外培养7天后，通过注射Adeno-LacZ获得腺特异性CTL克隆。以Adeno-HBX感染的Renca细胞或Adeno-HBX0感染的Renca细胞为靶细胞，进行标准的CTL检测。以Adeno-HBX感染的Renca细胞为靶细胞，与Adeno-HBX0感染的Renca细胞相比，铬的释放受到抑制。细胞内细胞因子(γ)染色定量证实了上述结果。我们还使用痘苗病毒(vvHBX或vvHBX0)对这些病毒进行了检查。体外和体内研究都显示出与使用腺病毒相同的趋势。这些证据表明，HBx通过抑制蛋白酶体来抑制抗原提呈。根据这些结果，我们推测HBx通过抑制蛋白酶体来抑制免疫逃逸后的自体提呈。

First, the expression of HBX protein was confirmed in adeno-HBX infected Renca cells (Balb/c mouse syngenic cell line), but not in adeno-HBX0 (HBX knockout) infected cells. Then, we examined MHC class I expression on the Renca cells infected with adeno-HBX or adeno-HBX0 (M.O.I.=0.5) 2 days after infection by flow cytometer. Its expression on the adeno-HBX infected Renca cells were significantly inhibited in comparison with that on the adeno-HBX0 infected Renca cells. Next, we tried to check the effect of HBX on cytotoxic lymphocyte (CTL) responses in vivo. We generated adeno-specific CTL clone by injection of adeno-LacZ to Balb/c mice intraperitoneally every 2 weeks, following ex vivo culture with fresh adeno-LacZ infected-dendritic cells for 7 days. A standard CTL assay was performed, using adeno-HBX infected Renca cells or adeno-HBX0 infected Renca cells as target cells. Chromium releasing was inhibited when we used adeno-HBX infected Renca cells as target cells, compared with adeno-HBX0 infected Renca cells. These results were quantitatively confirmed by intracellular cytokine (IFN-γ) staining. WE also examined these, using Vaccinia virus (vvHBX or vvHBX0). Both in vitro and in vivo study showed the same tendencies as using adeno-viruses. These pieces of evidences suggest that HBX inhibits antigen presentation through inhibition of proteasome. From these results, we speculate that HBX inhibits antoigen presentation through inhibition of proteasome, following immune escape.