Tamaki Laboratory, Aquatic Animal Health Division, National Research Institute of Aquaculture, Fisheries Research Agency, 224-1 Hiruta, Tamaki, Mie 519-0423, Japan.
Aquatic Animal Health Division, National Research Institute of Aquaculture, Fisheries Research Agency, Minami-Ise, Mie 516-0193, Japan.
J Gen Virol. 2013 Sep;94(Pt 9):2094-2101. doi: 10.1099/vir.0.052902-0. Epub 2013 Jun 19.
Red sea bream iridovirus (RSIV) is a representative of the genus Megalocytivirus which causes severe disease to aquaculture fish, mainly in Japan and South-east Asia. However, information to assess the viral kinetics of RSIV in fish is limited since reports on experimental infection by the immersion route, which is the natural infection route, are scarce. In this study, a method to evaluate the titre of RSIV was first developed. Experimental infections were continuously performed using RSIV cell culture as the inoculum to juvenile Japanese amberjack (Seriola quinqueradiata) (initial body weight 12.2 g) by immersion at three different concentrations. In addition, to investigate the prevalence of the virus among the organs of experimentally infected fish, viral DNA was measured at selected times by the real-time PCR method following viral inoculation by immersion. The developed titration method showed a 10(2) increase in sensitivity compared with the conventional method. We demonstrated that grunt fin cells can be used for continuous passage of RSIV. In the experimental infection, fish which were intraperitoneally injected with the RSIV cell culture or immersed with RSIV cell culture at 10(-2) and 10(-3) dilutions showed cumulative mortalities of 100 %. The results of measurements of the viral DNA of several organs from infected fish strongly suggest that the spleen is the target organ of RSIV in Japanese amberjack. Since the viral genome was detected from all the tested organs of two of five surviving fish which appeared to completely recover from the disease, it is suggested that these fish may become carriers.
真鲷虹彩病毒（RSIV）是一种属于 Megalocytivirus 属的病毒，可导致水产养殖鱼类发生严重疾病，主要在日本和东南亚地区流行。然而，由于有关通过浸泡途径（即自然感染途径）进行实验感染的报道很少，因此评估 RSIV 在鱼类中的病毒动力学的信息有限。在本研究中，首先开发了一种评估 RSIV 滴度的方法。通过连续使用 RSIV 细胞培养物作为接种物，通过浸泡将其接种到三个不同浓度的幼年黄尾鲷（Seriola quinqueradiata）（初始体重 12.2 g）中，进行实验感染。此外，为了研究实验感染鱼的器官中病毒的流行情况，在浸泡接种病毒后，通过实时 PCR 法在选定时间测量病毒 DNA。开发的滴定法与传统方法相比，灵敏度提高了 10(2)倍。我们证明了真鲷鳍细胞可用于 RSIV 的连续传代。在实验感染中，将 RSIV 细胞培养物经腹腔内注射或在 10(-2)和 10(-3)稀释度下浸泡的鱼出现了 100%的累计死亡率。从感染鱼的几种器官中测量病毒 DNA 的结果强烈表明，在黄尾鲷中，脾脏是 RSIV 的靶器官。由于从看起来完全从疾病中恢复的五尾幸存鱼中的两尾的所有测试器官中均检测到了病毒基因组，因此表明这些鱼可能成为携带者。
