Department of Pathology, Faculty of Veterinary Medicine, Suez Canal University, Ismailia 41522, Egypt.
Dis Aquat Organ. 2021 Feb 11;143:57-67. doi: 10.3354/dao03556.
The present study aimed to diagnose infectious myonecrosis virus (IMNV) and infectious hypodermal and hematopoietic necrosis virus (IHHNV) among cultured penaeid shrimp (Penaeus semisulcatus, n = 120) collected from private farms in 2 Egyptian provinces (Damietta and North Sinai) along the Mediterranean coast. The collected shrimp were subjected to clinical examination, histopathology, molecular characterization, and phylogenetic analysis. Most of the shrimp infected with IMNV showed a distinctive appearance resembling cooked shrimp and white necrosis on distal abdominal segments and tail fans. Simultaneously, IHHNV-infected cases displayed opaque abdominal muscles, white milky to buff mottling on the shell, and a pathognomonic runt-deformity syndrome. Histopathological examination of infected specimens revealed muscular edema, hemocyte infiltration, deformities, Zenker's necrosis, and eosinophilic intra-nuclear inclusion bodies (Cowdry type A). PCR results gave predictable amplicon sizes of 139 and 81 bp and confirmed the presence of IMNV and IHHNV with a total prevalence of 37.5 and 25%, respectively. A homology search by BLAST analysis showed that the retrieved isolates putatively belonged to IMNV and IHHNV based on 96.3 to 97% nucleotide identity to the corresponding open reading frame gene of each virus. The phylogenetic analysis clearly showed genetic similarity and cross-lineage between our isolates and other isolates from Egypt, the USA, Brazil, Indonesia, China, Korea, Taiwan, and Ecuador. In conclusion, gross inspection and histopathology may aid in the diagnosis of viral diseases; however, molecular tools are indispensable for confirming a possible infection. The current study recommends strict regulations during live shrimp transportation and implementing health control certificates over all imports and exports, especially in developing countries, including Egypt.
本研究旨在诊断来自埃及地中海沿岸两个省份（达米埃塔和北西奈）私人养殖场养殖的凡纳滨对虾（Penaeus semisulcatus，n = 120）中的传染性肌肉坏死病毒（IMNV）和传染性皮下及造血组织坏死病毒（IHHNV）。采集的虾进行临床检查、组织病理学检查、分子特征分析和系统发育分析。大多数感染 IMNV 的虾表现出独特的外观，类似于煮熟的虾，远端腹部节段和尾扇出现白色坏死。同时，感染 IHHNV 的虾表现为腹部肌肉不透明、壳上出现白色乳状至浅黄色斑驳、特有的侏儒畸形综合征。感染标本的组织病理学检查显示肌肉水肿、血球浸润、变形、肯氏坏死和嗜酸性核内包涵体（Cowdry 型 A）。PCR 结果得到了 139 和 81 bp 的可预测扩增片段，并证实了 IMNV 和 IHHNV 的存在，总流行率分别为 37.5%和 25%。BLAST 分析的同源性搜索表明，根据每个病毒相应开放阅读框基因的 96.3%至 97%核苷酸同一性，检索到的分离株推测属于 IMNV 和 IHHNV。系统发育分析清楚地显示了我们的分离株与来自埃及、美国、巴西、印度尼西亚、中国、韩国、中国台湾和厄瓜多尔的其他分离株之间的遗传相似性和跨谱系关系。总之，肉眼检查和组织病理学检查可能有助于诊断病毒性疾病；然而，分子工具对于确认可能的感染是不可或缺的。本研究建议在活虾运输过程中实施严格的规定，并对所有进出口，特别是包括埃及在内的发展中国家实施健康控制证书。
