Capsid protein C of tick-borne encephalitis virus tolerates large internal deletions and is a favorable target for attenuation of virulence
Capsid protein C of tick-borne encephalitis virus tolerates large internal deletions and is a favorable target for attenuation of virulence
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DOI：
10.1128/jvi.76.7.3534-3543.2002
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发表时间：
2002-04-01
影响因子：
5.4
通讯作者：
Mandl, CW
中科院分区：
文献类型：
--
作者：
Kofler, RM;Heinz, FX;Mandl, CW
在黄病毒蜱传脑炎（TBE）病毒的衣壳蛋白中引入大小范围为4至21个氨基酸残基的缺失。这些缺失逐渐影响存在于所有黄病毒衣壳蛋白序列中心的疏水结构域，并且其部分可以形成两亲性α-螺旋。在全长TBE基因组的情况下，缺失没有可测量地影响蛋白质表达，并且直到16个氨基酸残基的缺失长度，对应于几乎17%的成熟蛋白C，回收了活病毒。这种病毒是强烈减毒，但在成年小鼠中具有高度免疫原性，揭示衣壳蛋白C作为一个新的和有吸引力的目标，黄病毒的定向减毒。显然，较大的删除干扰了。感染性病毒颗粒的正确组装，并且病毒体组装的这种干扰可能是减毒的分子基础。然而，所有携带大缺失的突变体产生大量的亚病毒颗粒，从密度梯度分析判断，其与通过单独表达表面蛋白prM和E获得的重组亚病毒颗粒相同。在这项研究中揭示的蛋白C的结构和功能的灵活性，其预测的主要是α-螺旋构象是让人想起其他包膜的衣壳蛋白。病毒，如甲病毒（衣壳蛋白的N-末端结构域）、逆转录病毒和嗜肝DNA病毒，并表明所有这些可能属于一个共同的结构类别，这与许多二十面体病毒衣壳的经典P-桶结构根本不同。通过干扰病毒装配和有利于产生非感染性但高度免疫原性的亚病毒颗粒来减毒黄病毒的可能性为活黄病毒疫苗的开发开辟了一条有希望的新途径。
Deletions ranging in size from 4 to 21 amino acid residues were introduced into the capsid protein of the flavivirus tick-borne encephalitis (TBE) virus. These deletions incrementally affected a hydrophobic domain which is present at the center of all flavivirus capsid protein sequences and part of which may form an amphipathic alpha-helix. In the context of the full-length TBE genome, the deletions did not measurably affect protein expression and up to a deletion length of 16 amino acid residues, corresponding to almost 17% of mature protein C, viable virus was recovered. This virus was strongly attenuated but highly immunogenic in adult mice, revealing capsid protein C as a new and attractive target for the directed attenuation of flaviviruses. Apparently, the larger deletions interfered with the. correct assembly of infectious virus particles, and this disturbance of virion assembly is likely to be the molecular basis of attenuation. However, all of the mutants carrying large deletions produced substantial amounts of subviral particles, which as judged from density gradient analyses were identical to recombinant subviral particles as obtained by the expression of the surface proteins prM and E alone. The structural and functional flexibility of protein C revealed in this study and its predicted largely alpha-helical conformation are reminiscent of capsid proteins of other enveloped. viruses, such as alphaviruses (N-terminal domain of the capsid,protein), retroviruses, and hepadnaviruses and suggest that all of these may belong to a common structural class, which is fundamentally distinct from the classical P-barrel structures of many icosahedral viral capsids. The possibility of attenuating flaviviruses by disturbing virus assembly and favoring the production of noninfectious but highly immunogenic subviral particles opens up a promising new avenue for the development of live flavivirus vaccines.