AARM/FAB, School of Environment, Resources and Development, Asian Institute of Technology, Pathum Thani, Thailand.
Fish Heath Platform, Center of Excellence for Shrimp Molecular Biology and Biotechnology (Centex Shrimp), Faculty of Science, Mahidol University, Bangkok, Thailand.
J Fish Dis. 2022 Sep;45(9):1323-1331. doi: 10.1111/jfd.13663. Epub 2022 May 30.
Tilapia parvovirus (TiPV) is an emerging virus reportedly associated with disease and mortality in farmed tilapia. Although previous descriptions of histopathological changes are available, the lesions reported in these are not pathognomonic. Here, we report Cowdry type A inclusion bodies (CAIB) in the pancreas as a diagnostic histopathological feature found in adult Nile tilapia naturally infected with TiPV. This type of inclusion body has been well-known as a histopathological landmark for the diagnosis of other parvoviral infections in shrimp and terrestrial species. Interestingly, this lesion could be exclusively observed in pancreatic acinar cells, both in the hepatopancreas and pancreatic tissue along the intestine. In situ hybridization (ISH) using a TiPV-specific probe revealed the intranuclear presence of TiPV DNA in multiple tissues, including the liver, pancreas, kidney, spleen, gills and the membrane of oocytes in the ovary. These findings suggest that although TiPV can replicate in several tissue types, CAIB manifest exclusively in pancreatic tissues. In addition to TiPV, most diseased fish were co-infected with Streptococcus agalactiae, and presented with multifocal granulomas secondary to this bacterial infection. Partial genome amplification of TiPV was successful and revealed high nucleotide identity (>99%) to previously reported isolates. In summary, this study highlights the usefulness of pancreatic tissue as a prime target for histopathological diagnosis of TiPV in diseased Nile tilapia. This pattern may be critical when determining the presence of TiPV infection in new geographic areas, where ancillary testing may not be available. TiPV pathogenesis in this landmark organ warrants further investigation.
罗非鱼细小病毒（TiPV）是一种新兴病毒，据报道与养殖罗非鱼的疾病和死亡率有关。尽管以前有关于组织病理学变化的描述，但这些报道中的病变并非特异性的。在这里，我们报告了在自然感染 TiPV 的成年尼罗罗非鱼的胰腺中发现的 Cowdry 型 A 包涵体（CAIB）作为一种诊断组织病理学特征。这种包涵体已被广泛认为是虾类和陆生物种中其他细小病毒感染的组织病理学诊断标志。有趣的是，这种病变仅能在胰腺腺泡细胞中观察到，无论是在肝胰腺还是沿肠分布的胰腺组织中。使用 TiPV 特异性探针的原位杂交（ISH）显示 TiPV DNA 存在于多种组织中，包括肝脏、胰腺、肾脏、脾脏、鳃和卵巢卵母细胞膜。这些发现表明，尽管 TiPV 可以在多种组织类型中复制，但 CAIB 仅在胰腺组织中表现出来。除了 TiPV，大多数患病鱼还同时感染了无乳链球菌，并因这种细菌感染而出现多灶性肉芽肿。TiPV 的部分基因组扩增成功，并显示出与以前报道的分离株高度核苷酸同一性（>99%）。总之，本研究强调了胰腺组织作为患病尼罗罗非鱼 TiPV 组织病理学诊断的主要靶标。当在新的地理区域确定 TiPV 感染的存在时，这种模式可能至关重要，因为可能无法进行辅助检测。TiPV 在这个标志性器官中的发病机制值得进一步研究。
