Qian D, Shi Z, Zhang S, Cao Z, Liu W, Li L, Xie Y, Cambournac I, Bonami J-R
Joint-Laboratory of Invertebrate Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, People's Republic of China.
J Fish Dis. 2003 Sep;26(9):521-7. doi: 10.1046/j.1365-2761.2003.00486.x.
A disease of Macrobrachium rosenbergii, the giant freshwater prawn, farmed in China was recently recorded in Zhejiang, Jiangsu, Shanghai, Guangxi and Guangdong provinces. The clinical sign of the disease, which develops in post-larvae (PL), is a whitish appearance of the muscles, particularly noticeable in the abdomen. Mortalities may reach 100% in some hatcheries. Investigations by transmission electron microscopy after negative staining of diseased PL homogenates showed the presence of two types of viral particles: one, unenveloped, icosahedral in shape, 26-27 nm in diameter, the second, much smaller, about 14-16 nm in diameter, designated extra small virus particle (XSV). The large virus has a genome with two pieces of ssRNA (RNA-1 and RNA-2), of 3 and 1.2 kb, respectively. Hybridization tests confirmed that this large virus is closely related to M. rosenbergii nodavirus (MrNV) which was isolated from diseased prawns in a hatchery in the French West Indies. Its very small size and hypothesized biochemical and biological characteristics suggest XSV is a new type of crustacean virus. As XSV has always been found associated with the larger virus (nodavirus) and is located in muscle and connective cells of diseased animals, it could be an autonomous virus, a helper-type virus or a satellite-like virus.
中国养殖的罗氏沼虾（一种大型淡水虾）出现的一种疾病最近在浙江、江苏、上海、广西和广东省被记录。这种疾病在幼体后期（PL）出现，临床症状是肌肉呈现白色外观，在腹部尤为明显。在一些孵化场，死亡率可能达到100%。对患病PL匀浆进行负染色后通过透射电子显微镜检查发现存在两种病毒颗粒：一种是无包膜的二十面体形状，直径26 - 27纳米；另一种要小得多，直径约14 - 16纳米，被称为超小病毒颗粒（XSV）。大病毒的基因组有两条单链RNA（RNA - 1和RNA - 2），分别为3千碱基和1.2千碱基。杂交试验证实这种大病毒与从法属西印度群岛一个孵化场患病对虾中分离出的罗氏沼虾诺达病毒（MrNV）密切相关。其非常小的尺寸以及推测的生化和生物学特性表明XSV是一种新型甲壳类病毒。由于XSV总是与较大的病毒（诺达病毒）相关联，并且位于患病动物的肌肉和结缔组织细胞中，它可能是一种自主病毒、辅助型病毒或类卫星病毒。
