Poornima M, Seetang-Nun Y, Alavandi S V, Dayal J Syama
Central Institute of Brackishwater Aquaculture, Chennai, 600028 India.
Indian J Virol. 2012 Sep;23(2):215-25. doi: 10.1007/s13337-012-0099-7. Epub 2012 Sep 18.
Among the emerging diseases in shrimp aquaculture, monodon slow growth syndrome (MSGS) is a major concern in South and Southeast Asia. Shrimp farming in Thailand was severely affected during 2000-2002 due to MSGS, which caused an economic loss, of about US$ 300 million. MSGS is characterized by abnormally slow growth with coefficients of size variation of >35 %, that has impacted P. monodon production in Thailand. A new shrimp virus, Laem-Singh virus (LSNV) was identified to be associated in MSGS affected shrimp. LSNV a RNA virus of about 25 nm diameter is phylogenetically related to the insect-borne viruses in the families Barnaviridae, Tymoviridae and Sobemoviridae an important histopathological observation is exclusively noticed in growth-retarded shrimp. The LSNV infections have been confirmed in various organs of infected shrimp such as lymphoid organ, gills and nervous tissues by various diagnostic techniques such as reverse transcription polymerase chain reaction (RT-PCR), in situ hybridization, quantitative real-time RT-PCR and reverse transcription loop-mediated isothermal amplification combined with a lateral flow dipstick (RT-LAMP-LFD) and these tools are available for the diagnosis of LSNV. Recently, an integrase containing element has been identified in absolute association with LSNV in stunted growth shrimp. The transmission of LSNV through horizontal and vertical routes has been experimentally demonstrated. The known natural host-range of LSNV includes P. monodon and other penaeid shrimp. The putative RdRp gene involved in replication of LSNV was targeted for dsRNA-mediated gene silencing and appeared to be effective in a dose-dependent manner. Since the discovery of LSNV in 2006 in Thailand, it has been added to the list of viruses to be excluded from domesticated specific pathogen-free stocks of P. monodon and it has been recommended that shrimp farmers avoid stocking post larvae positive for LSNV to prevent MSGS in their farms.
在对虾养殖中出现的新兴疾病中，斑节对虾生长缓慢综合征（MSGS）是南亚和东南亚地区主要关注的问题。2000年至2002年期间，泰国的对虾养殖因MSGS受到严重影响，造成了约3亿美元的经济损失。MSGS的特征是生长异常缓慢，大小变异系数>35%，这影响了泰国斑节对虾的产量。一种新的对虾病毒，莱姆 - 辛格病毒（LSNV）被确定与受MSGS影响的对虾有关。LSNV是一种直径约25纳米的RNA病毒，在系统发育上与Barnaviridae、Tymoviridae和Sobemoviridae科的虫媒病毒有关，在生长迟缓的对虾中专门观察到一个重要的组织病理学现象。通过逆转录聚合酶链反应（RT-PCR）、原位杂交、定量实时RT-PCR和逆转录环介导等温扩增结合侧向流动试纸条（RT-LAMP-LFD）等各种诊断技术，已在受感染对虾的各种器官（如淋巴器官、鳃和神经组织）中证实了LSNV感染，并且这些工具可用于LSNV的诊断。最近，在生长发育迟缓的对虾中发现了一种与LSNV绝对相关的整合酶元件。已通过实验证明了LSNV通过水平和垂直途径的传播。LSNV已知的天然宿主范围包括斑节对虾和其他对虾科对虾。参与LSNV复制的推定RNA依赖性RNA聚合酶（RdRp）基因被用于dsRNA介导的基因沉默，并且似乎以剂量依赖的方式有效。自2006年在泰国发现LSNV以来，它已被列入从斑节对虾的驯化无特定病原体种群中排除的病毒名单，并且建议对虾养殖户避免放养LSNV呈阳性的后期幼体，以防止其养殖场出现MSGS。
