2022—2023年虾类传染性肌坏死病毒(IMNV)流行情况调查

Investigation of the prevalence of infectious myonecrosis virus (IMNV) from 2022 to 2023

中文关键词: 传染性肌坏死病毒(IMNV)  流行病学  TaqMan RT-qPCR  组织病理  组织原位杂交

英文关键词: Infectious myonecrosis virus (IMNV)  Epidemiology  TaqMan RT-qPCR  Tissue histopathology  In situ hybridization

中文摘要:

      2020年，由传染性肌坏死病毒(infectious myonecrosis virus，IMNV)引起的虾类传染性肌坏死(infectious myonecrosis，IMN)首次在中国暴发，使对虾养殖产业遭受了严重的经济损失。为掌握近年IMNV在我国的流行情况，2022—2023年间，本研究在全国主要虾类养殖地区开展了IMNV流行病学调查，并利用分子生物学、组织病理学等方法对所采集的样本进行分析。在山东、江苏、浙江、海南、天津、广西、福建、河北等地开展流行病学调查并采集样品829份，所采集的样品包括凡纳对虾(Penaeus vannamei)、日本对虾(P. japonicus)、中国对虾(P. chinensis)与罗氏沼虾(Macrobrachium rosenbergii)等主要养殖虾类以及饵料、其他水产经济物种和养殖用水。采用TaqMan探针实时荧光定量PCR (TaqMan RT-qPCR)对所采集的样品进行了IMNV检测。调查中发现，患病对虾腹节或尾节骨骼肌出现IMN感染样的典型斑块状或弥散性白色坏死症状，凡纳对虾、日本对虾、中国对虾等主要养殖虾类中均可检测到IMNV阳性，阳性样品主要来自环渤海地区的山东、河北、天津等省市；除养殖虾类外，采集的虾类鲜活饵料(主要是中华卤虫Artemia sinica)和养殖场抽滤的近海海水中也可检测到IMNV阳性。2022年所采集样品中IMNV阳性检出率为6.27% (23/367)，2023年所采集样品中IMNV阳性检出率为15.80% (73/462)。对TaqMan RT-qPCR检测呈阳性的样品进行组织病理与原位杂交分析，病虾腹节和尾节发白肌肉组织切片中可见IMNV感染特征性凝固状坏死，且发生病理损伤的肌肉组织中有明显的IMNV探针蓝紫色杂交信号。本研究表明，2022—2023年间我国多省市的养殖对虾、生物饵料及近海海水中存在较高的IMNV阳性检出率，虾类养殖过程中需加强IMNV检测与监测预警，以降低其进一步扩散与流行危害风险。

英文摘要:

      Infectious muscle necrosis (IMN) caused by infectious myonecrosis virus (IMNV) broke out for the first time in Chinese shrimp in 2020, causing substantial economical loss to the shrimp farming industry. To understand the prevalence of Chinese IMNV in recent years, an epidemiological survey of IMNV was conducted in major Chinese shrimp farming areas between 2022–2023. Samples were analyzed using molecular biology and histopathology. A total of 829 samples were collected from Shandong, Jiangsu, Zhejiang, Hainan, Tianjin, Guangxi, Fujian, and Hebei. These samples included major farmed shrimp species, such as Penaeus vannamei, P. japonicas, P. chinensis, and Macrobrachium rosenbergii, as well as live feed, other aquatic economic species, and culture water. TaqMan real-time quantitative fluorescence RT-PCR (TaqMan RT-qPCR) was used for molecular detection. The skeletal muscle of diseased shrimp exhibited the typical plaque or diffuse white necrosis symptom of IMNV infection. IMNV was detected in major farmed shrimp species such as P. vannamei, P. japonicus, and P. chinensis. The positive samples were mainly distributed in Shandong, Hebei, Tianjin, and other provinces or cities around the Bohai Sea. In addition to farmed shrimp, IMNV-positive shrimp live bait (mainly Artemia) and offshore seawater filtered close to the farm was also detected. The IMNV-positive rates of samples collected in 2022 and 2023 were 6.27% (23/367) and 15.80% (73/462), respectively. The IMNV-positive TaqMan RT-qPCR samples were further analyzed using histopathological and in situ hybridization methods. The characteristic coagulation necrosis of IMNV infection was found in the white muscle tissue sections of the ventral and caudal segments of the diseased shrimp, with a clear blue-violet hybridization signal of the IMNV probe in the muscle tissue with pathological damage. The results of this study indicated a high positive rate of IMNV in cultured shrimp, biological live bait, and offshore seawater in many Chinese provinces between 2022–2023. Detection, monitoring, and early warning of IMNV infection in the shrimp farming process should be strengthened to reduce the risk of further spread and IMN epidemics.