Faculty of Veterinary Medicine, Department of Veterinary Microbiology and Immunology, Kasetsart University, Bangkok, Thailand.
Aquatic Animal Health Laboratory, Department of Pathobiology and Diagnostic Investigation, CVM & Department of Fisheries and Wildlife, CANR - Michigan State University, East Lansing, MI, USA.
Transbound Emerg Dis. 2021 Nov;68(6):3136-3144. doi: 10.1111/tbed.14143. Epub 2021 May 22.
The recently discovered Tilapia parvovirus (TiPV) was the first Parvovirus confirmed to infect fish, causing mortality outbreaks in farmed adult Nile tilapia in China. Severe mortality outbreaks caused by Tilapia tilapinevirus (TiLV) to farmed tilapia in Thailand revealed the concomitant occurrence of TiPV. Out of ten fish farms screened, TiPV was detected in one site rearing juvenile red hybrid tilapia. Clinical signs included abnormal swimming, scale protrusion, skin and muscle haemorrhaging, exophthalmia and generalized anaemia. Histological findings showed extensive infiltration of lymphocytes, with increased melanomacrophage centres in the anterior kidney and spleen, erythrocyte depletion in the spleen and hepatic syncytial cells. Both TiLV and TiPV were systemically distributed in the body of moribund fish. The analysis of the near-complete TiPV genome isolated from Thailand revealed 98.74% sequence identity to the formerly isolated from China, together with a highly conserved and comparable genomic organization and with a 3 nucleotides deletion in the 5-UTR. The viral genome structure was highly conserved for each of its components, with nucleotide and amino acid identity ranging from 100% for ORF1 to 97% for ORF2, and with conserved HuH and Walker loop motifs within NS1. Taken together, our results document the first detection of TiPV outside China, thus for the first time in Thailand. Moreover, TiPV was detected for the first time during a natural occurrence in farmed red hybrid tilapia and involved in co-infection pattern with TiLV. Diagnostic investigations during tilapia disease outbreaks should include the screening for TiPV. Further studies are needed to elucidate TiPV genomic variance, pathobiology, including focussing on the outcomes of TiLV-TiPV co-infection patterns, necessary to enable risk assessment for the worldwide spreading of TiPV and to design adequate control measures against these emerging viruses in tilapia.
最近发现的罗非鱼细小病毒 (TiPV) 是首例确认感染鱼类的细小病毒，在中国导致养殖成鱼尼罗罗非鱼大量死亡。在泰国，对养殖罗非鱼的Tilapia tilapinevirus (TiLV) 严重暴发的研究揭示了 TiPV 的同时发生。在筛查的十个鱼场中，在一个养殖幼年红杂交罗非鱼的地点检测到 TiPV。临床症状包括异常游动、鳞片突出、皮肤和肌肉出血、眼球突出和全身性贫血。组织学检查显示广泛的淋巴细胞浸润，前肾和脾脏的黑色素巨噬细胞中心增加，脾脏和肝合胞体细胞中红细胞耗竭。濒死鱼体内系统分布着 TiLV 和 TiPV。从泰国分离出的近乎完整的 TiPV 基因组分析表明，其与中国以前分离的病毒序列同源性为 98.74%，基因组结构高度保守且可比，在 5-UTR 中有 3 个核苷酸缺失。病毒基因组的每个组成部分的结构都高度保守，ORF1 的核苷酸和氨基酸同一性为 100%，ORF2 为 97%，NS1 内有保守的 HuH 和 Walker 环基序。总之，我们的结果记录了 TiPV 在泰国的首次检出，也是在中国以外的首次检出。此外，TiPV 是在养殖红杂交罗非鱼的自然发病中首次检出，并与 TiLV 共同感染。在罗非鱼疾病暴发的诊断调查中，应包括对 TiPV 的筛查。需要进一步研究以阐明 TiPV 的基因组变异、发病机制，包括关注 TiLV-TiPV 共同感染模式的结果，这对于评估 TiPV 在全球的传播风险以及设计针对这些新兴病毒的控制措施至关重要。
