New Parallels in Positive Strand RNA Virus, Retrovirus and Dsrna Virus Replication

〔ウイルス 第５３巻 第１号，pp．５３，２００３〕

第５０回日本ウイルス学会学術集会イブニングシンポジウム 特集３ 「ウイルス遺伝子操作技術の進展と応用」

１．New Parallels in Positive Strand RNA Virus, Retrovirus and dsRNA Virus Replication

Paul Ahlquist１，２，Michael Schwartz１，２，Jianbo Chen１，Michael Janda１，２， Johan den Boon１，Michael Sullivan１ andDavidMiller１

All positive strand RNA viruses replicate their RNA on which become the sites of viral RNA synthesis and retain host membranes in association with vesicles or other （－）RNA templates for（＋）RNA synthesis. membrane alterations, but the nature and function of this Similarly, we find that RNA replication by another, very membrane association and organization of the replication distinct positive―strand RNA virus, the nodavirus Flock complex have been poorly understood. House virus, takes place on mitochondria in association Brome mosaic virus（BMV）,inthealphavirus―like su- with similar spherular invaginations of the outer mitochon- perfamily, encodes two interacting RNA replication pro- drial membrane. teins：１a, with helicase―like and RNA capping domains, The results explain many widely conserved features of and２apolymerase. We find that BMV１a,２apolymerase positive strand RNA virus replication. The similarities re- and a specific cis―acting replication signal recapitulate the vealed bridge retroviruses, positive strand RNA viruses functions of Gag, Pol and RNA packaging signals in and dsRNA viruses, which also sequester RNA templates, retrovirus cores. Prior to RNA replication，１aformscapsid RNA polymerase and often RNA capping functions in a ―like spherules that partially bud into the endoplasmic re- protein shell or core. ticulum membrane, sequestering viral positive strand These and other features imply that all three virus RNA templates. A defined viral RNA signal is necessary classes, which all replicate via mRNA intermediates, use and sufficient for this template sequestration. When ex- related mechanisms for nucleic acid replication and may pressed, ２apolymerase co―localizes in thesespherules, have evolved from common ancestors.

１Institute for Molecular Virology and ２Howard Hughes Medical Institute University of Wisconsin―Madison, １５２５Linden Dr., Madison, WI５３７０６―１５９６,USA