Research Faculty of Agriculture, Hokkaido University, Kita 9 Nishi9, Kita-ku, Sapporo, Japan.
Virology. 2013 Aug 1;442(2):180-8. doi: 10.1016/j.virol.2013.04.015. Epub 2013 May 13.
Asparagus virus 2 (AV-2) is a member of the genus Ilarvirus in the family Bromoviridae. We cloned the coat protein (CP) and the 2b protein (2b) genes of AV-2 isolates from asparagus plants from various regions and found that the sequence for CP and for 2b was highly conserved among the isolates, suggesting that AV-2 from around the world is almost identical. We then made an AV-2 infectious clone by simultaneous inoculation with in vitro transcripts of RNAs 1-3 of AV-2 and in vitro-synthesized CP, which is necessary for initial infection. Because 2b of cucumoviruses in Bromoviridae can suppress systemic silencing as well as local silencing, we analyzed whether there is functional synteny of 2b between AV-2 and cucumovirus. Using the AV-2 infectious clone, we here provided first evidence that Ilarvirus 2b functions as an RNA silencing suppressor; AV-2 2b has suppressor activity against systemic silencing but not local silencing.
芦笋病毒 2（AV-2）是韧皮部布罗病毒科玉兰病毒属的成员。我们从不同地区的芦笋植物中克隆了 AV-2 分离株的外壳蛋白（CP）和 2b 蛋白（2b）基因，发现 CP 和 2b 的序列在分离株中高度保守，表明来自世界各地的 AV-2 几乎相同。然后，我们通过同时接种 AV-2 的 RNA1-3 的体外转录物和体外合成的 CP 制作了 AV-2 的传染性克隆，这对于初始感染是必要的。由于韧皮部布罗病毒中的黄瓜花叶病毒 2b 可以抑制系统沉默和局部沉默，我们分析了 AV-2 和黄瓜花叶病毒之间 2b 是否存在功能同线性。使用 AV-2 传染性克隆，我们首次提供了证据证明玉兰病毒 2b 作为 RNA 沉默抑制剂的功能；AV-2 2b 对系统沉默具有抑制活性，但对局部沉默没有抑制活性。
