Poulos Bonnie T, Tang Kathy F J, Pantoja Carlos R, Bonami Jean Robert, Lightner Donald V
Aquaculture Pathology Laboratory, Department of Veterinary Science and Microbiology, The University of Arizona, 1117 E. Lowell Street, Tucson, AZ 85721, USA.
UMR 5098, CNRS/IFREMER/UM2, cc080 Place E. Bataillon, 34095 Montpellier Cedex 5, France.
J Gen Virol. 2006 Apr;87(Pt 4):987-996. doi: 10.1099/vir.0.81127-0.
The causative agent of myonecrosis affecting cultured Penaeus vannamei in Brazil was demonstrated to be a virus after purification of the agent from infected shrimp tissues. Purified viral particles were injected into specific pathogen-free P. vannamei, resulting in a disease that displayed the same characteristics as those found in the original shrimp used for purification. The virus was named infectious myonecrosis virus (IMNV). The viral particles were icosahedral in shape and 40 nm in diameter, with a buoyant density of 1.366 g ml(-1) in caesium chloride. The genome consisted of a single, double-stranded (dsRNA) molecule of 7560 bp. Sequencing of the viral genome revealed two non-overlapping open reading frames (ORFs). The 5' ORF (ORF 1, nt 136-4953) encoded a putative RNA-binding protein and a capsid protein. The coding region of the RNA-binding protein was located in the first half of ORF 1 and contained a dsRNA-binding motif in the first 60 aa. The second half of ORF 1 encoded a capsid protein, as determined by amino acid sequencing, with a molecular mass of 106 kDa. The 3' ORF (ORF 2, nt 5241-7451) encoded a putative RNA-dependent RNA polymerase (RdRp) with motifs characteristic of totiviruses. Phylogenetic analysis based on the RdRp clustered IMNV with Giardia lamblia virus, a member of the family Totiviridae. Based on these findings, IMNV may be a unique member of the Totiviridae or may represent a new dsRNA virus family that infects invertebrate hosts.
从感染对虾组织中纯化出病原体后，经证实，巴西养殖凡纳滨对虾发生肌肉坏死的病原体是一种病毒。将纯化的病毒颗粒注射到无特定病原体的凡纳滨对虾体内，引发的疾病表现出与用于纯化的原始对虾相同的特征。该病毒被命名为传染性肌肉坏死病毒（IMNV）。病毒颗粒呈二十面体形状，直径为40纳米，在氯化铯中的浮力密度为1.366克/毫升。基因组由一个7560碱基对的单双链（dsRNA）分子组成。病毒基因组测序揭示了两个不重叠的开放阅读框（ORF）。位于5'端的ORF（ORF 1，核苷酸136 - 4953）编码一个假定的RNA结合蛋白和一个衣壳蛋白。RNA结合蛋白的编码区位于ORF 1的前半部分，在前60个氨基酸中包含一个dsRNA结合基序。经氨基酸测序确定，ORF 1的后半部分编码一个分子量为106 kDa的衣壳蛋白。位于3'端的ORF（ORF 2，核苷酸5241 - 7451）编码一个具有双病毒特征基序的假定RNA依赖的RNA聚合酶（RdRp）。基于RdRp的系统发育分析将IMNV与贾第虫病毒聚类在一起，贾第虫病毒是双病毒科的一个成员。基于这些发现，IMNV可能是双病毒科的一个独特成员，或者可能代表一个感染无脊椎动物宿主的新的dsRNA病毒科。
