Virology：流感病毒启动子/复制起点研究中取得的进展

　　10月16日，国际学术期刊Virology在线发表了中国科学院上海巴斯德研究所丰田哲也研究组最新研究成果，揭示了流感病毒基因组C4启动子/复制起点具有较弱的聚合酶识别活性，从而减弱了流感病毒的转录和复制。

　　流感病毒基因组具有8个负链RNA片段。在自然情况下，甲型流感病毒基因组片段3’末端第四位存在U(U4)或C(C4)的变异。博士研究生蒋红兵等在丰田哲也的指导下，通过深入分析并比较了U4和C4启动子/复制起点的活性差异，发现C4的复制子活性只有U4的28%。他们利用纯化的流感病毒RNA聚合酶在体外分别比较了它以U4 [v84(U4)]、C4 [v84(C4)]和互补RNA链（c84）为模板的转录和复制活性差异。实验结果表明，无论是复制还是转录，U4的活性都要比C4高。进一步研究发现，U4和C4启动子/复制起点的活性差异主要来自于聚合酶对两种不同的启动子/复制起点识别结合活性差异。此外，他们还构建了8个基因组片段全部突变为U4或C4启动子/复制起点的突变体流感病毒，并检测了它们在细胞内的生长活力差异和在老鼠体内的致病力差异。实验表明，U4突变体病毒在细胞上的生长活力增强；而C4突变体病毒在细胞上的生长活力则减弱了。但U4或C4突变体病毒在老鼠体内的致病性却都低于野生型WSN病毒。

　　上述研究结果为监测、分析流感病毒的毒力以及制备流感减毒活疫苗提供了新的思路。

　　该研究得到了中国科学院、国家自然科学基金、李嘉诚基金会、RESPARI项目和欧盟第六框架项目(FLUINNATE)的资助。

　　推荐英文摘要：

　　Virology doi:10.1016/j.virol.2010.09.022

　　Influenza virus genome C4 promoter/origin attenuates its transcription and replication activity by the low polymerase recognition activity

　　Hongbing Jiang1, a, Shijian Zhang1, a, Qiang Wanga, Jinlan Wanga, Liqing Genga and Tetsuya Toyoda, a,

　　a Unit of Viral Genome Regulation, Institut Pasteur of Shanghai, Key Laboratory of Molecular Virology & Immunology, Chinese Academy of Sciences, 411 Hefei Road, Shanghai 200025, PR China

　　A natural variation is observed at position 4 of the 3′-end of influenza A virus genomes, where U (U4) or C (C4) is present. The replicon activity of C4 was 28% of U4. We compared the transcription and replication activity of U4 [v84(U4)], C4 [v84(C4)] and the complimentary RNA (c84) using the purified influenza virus RNA polymerase in vitro. ApG-primed replication activities of v84(C4) and c84 were 23.8% and 7.8% of v84(U4). Globin mRNA-primed transcription activities of v84(C4) and c84 were 36.9% and 6.81% of v84(U4). De novo replication activities of v84(C4) and c84 were 21.3 and 10.2% of v84(U4). This difference came from their polymerase binding activity. When all the eight genome segments of WSN strain were changed to U4, the virus titer was 760 times higher than the wild type. However, its pathogenicity in mice was lower than the wild type.