Sacher R, French R, Ahlquist P
Institute for Molecular Virology, University of Wisconsin, Madison 53706.
Virology. 1988 Nov;167(1):15-24. doi: 10.1016/0042-6822(88)90049-9.
Brome mosaic virus (BMV) is an icosahedral virus with a tripartite RNA genome which infects monocotyledonous plants, while the cowpea or legume strain of tobacco mosaic virus (CcTMV) is a rod-shaped virus with a single component RNA genome which infects dicotyledonous plants. To examine the potential for exchanging entire genes between RNA viruses, biologically active cDNA clones were used to replace the natural coat gene of BMV RNA3 with the coat gene and encapsidation origin of CcTMV. In protoplasts coinoculated with BMV RNAs 1 and 2, the resulting hybrid RNA3 was replicated by BMV trans-acting factors but was packaged in TMV coat protein to give rod-shaped particles rather than the usual BMV icosahedra. When the CcTMV encapsidation origin was suitably inserted in derivatives of BMV RNAs 1 and 2, these RNAs were also packaged in a ribonuclease-resistant form in protoplasts coinoculated with the hybrid RNA3 expressing TMV rather than BMV coat protein. Thus, despite the markedly divergent nature of BMV and TMV, replicating hybrids bearing characters derived from both parent viruses were produced. Such hybrid viruses could be of considerable value for studying specific steps in infection and for assigning functions to particular virus genes.
雀麦花叶病毒（BMV）是一种具有三分体RNA基因组的二十面体病毒，可感染单子叶植物，而烟草花叶病毒的豇豆或豆科毒株（CcTMV）是一种具有单组分RNA基因组的杆状病毒，可感染双子叶植物。为了研究RNA病毒之间交换完整基因的可能性，使用具有生物活性的cDNA克隆，用CcTMV的外壳基因和衣壳化起始位点取代BMV RNA3的天然外壳基因。在用BMV RNA1和RNA2共同接种的原生质体中，产生的杂交RNA3由BMV反式作用因子复制，但被包装在TMV外壳蛋白中，形成杆状颗粒，而不是通常的BMV二十面体。当将CcTMV衣壳化起始位点适当地插入BMV RNA1和RNA2的衍生物中时，这些RNA在与表达TMV而非BMV外壳蛋白的杂交RNA3共同接种的原生质体中也以抗核糖核酸酶的形式被包装。因此，尽管BMV和TMV在性质上有明显差异，但仍产生了具有来自两种亲本病毒特征的复制性杂种。这种杂种病毒对于研究感染的特定步骤以及为特定病毒基因赋予功能可能具有相当大的价值。
