天津地区1例凡纳滨对虾病害的病原学检测与分析
Pathogenic Detection and Analysis of a Case of Litopenaeus vannamei Disease in Tianjin

采用流行病学调查、细菌分离鉴定、寄生虫观察和分子生物学方法对天津滨海新区凡纳滨对虾养殖场采集的1例患病凡纳滨对虾(Litopenaeus vannamei)样品开展病原学研究。寄生虫和细菌鉴定结果显示，患病对虾未发现寄生虫和细菌感染；病原学检测结果显示，患病对虾虾肝肠胞虫(EHP)和传染性肌坏死病毒(IMNV)核酸检测结果均为阳性，其它相关病原检测结果均为阴性；EHP、IMNV目的基因产物测序后经NCBI BLAST，与已报道的EHP、IMNV相关序列相似性分别介于99.56%~100%、98.33%~100%；系统发育树分析结果显示，本研究EHP孢壁蛋白1基因与马来西亚分离株、印度尼西亚分离株、泰国分离株及印度分离株的EHP孢壁蛋白1基因聚为一支，亲缘关系较近；IMNV TJ2022 OQ438431与印度尼西亚分离株、印度分离株、巴西分离株聚为一支，亲缘关系较近。揭示本研究凡纳滨对虾发病样品可能由EHP和IMNV感染所致，需引起养殖从业者的高度关注。
In this article, the laboratory diagnostic analysis, including epidemiological investigation, isolation and identification of bacteria, microscopic observation of parasites and PCR detection of various pathogenic bacteria in shrimp were carried out to identify the pathogen of diseased Litopenaeus vannamei in Tianjin Binhai district. The identification results of parasites and bacteria showed that there were no parasites and bacterial infections in this batch of diseased shrimp; The results of pathogenic PCR showed that EHP and IMNV were positive; The sequences of the PCR products showed 99.56% to 100%, and 98.33% to 100% similarity with the reported EHP and IMNV separately, after sequencing and BLAST on NCBI. The phylogenetic analysis of the target sequence showed that the amplified EHP gene sequence had the highest similarity with the EHP cell wall protein 1 sequence of Malaysia isolate, Indonesia isolate, Thailand isolate and India isolate; the amplified IMNV gene sequence had high affinity with the Indonesian isolate, Indian isolate and Brazilian isolate of each year, which was clustered into one branch. It was revealed that the diseased Litopenaeus vannamei may be caused by the co-infection of EHP and IMNV, which should pay more attention.