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Viral haemorrhagic septicaemia (VHS), caused by the novirhabdovirus viral haemorrhagic septicaemia virus (VHSV), causes significant economic problems to European rainbow trout, Oncorhynchus mykiss (Walbaum), production. The virus isolates can be divided into four distinct genotypes with additional subgroups. The main source of outbreaks in European rainbow trout farming is sublineage Ia isolates. Recently, this group of isolates has been further subdivided in to two subclades of which the Ia‐2 consists of isolates occurring mainly in Continental Europe outside of Denmark. In this study, we sequenced the full‐length G‐gene sequences of 24 VHSV isolates that caused VHS outbreaks in Polish trout farms between 2005 and 2009. All these isolates were identified as genotype Ia‐2; they divided however into two genetically distinct subgroups, that we name Pol I and Pol II. The Pol I isolates mainly caused outbreaks in the southern part of Poland, while Pol II isolates predominantly were sampled in the north of Poland, although it seems that they have been transmitted to other parts of the country. Molecular epidemiology was used for characterization of transmission pathways. This study shows that a main cause of virus transmission appears to be movement of fish. At least in Polish circumstances trading practices appear to have significant impact on spreading of VHSV infection. 相似文献
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Melena J Bayot B Betancourt I Amano Y Panchana F Alday V Calderón J Stern S Roch P Bonami JR 《Journal of fish diseases》2006,29(10):589-600
Larvae and post-larvae of Penaeus vannamei (Boone) were submitted to primary challenge with infectious hypodermal and haematopoietic necrosis virus (IHHNV) or formalin-inactivated white spot syndrome virus (WSSV). Survival rate and viral load were evaluated after secondary per os challenge with WSSV at post-larval stage 45 (PL45). Only shrimp treated with inactivated WSSV at PL35 or with IHHNV infection at nauplius 5, zoea 1 and PL22 were alive (4.7% and 4%, respectively) at 10 days post-infection (p.i.). Moreover, at 9 days p.i. there was 100% mortality in all remaining treatments, while there was 94% mortality in shrimp treated with inactivated WSSV at PL35 and 95% mortality in shrimp previously treated with IHHNV at N5, Z1 and PL22. Based on viral genome copy quantification by real-time PCR, surviving shrimp previously challenged with IHHNV at PL22 contained the lowest load of WSSV (0-1x10(3) copies microg-1 of DNA). In addition, surviving shrimp previously exposed to inactivated WSSV at PL35 also contained few WSSV (0-2x10(3) copies microg-1 of DNA). Consequently, pre-exposure to either IHHNV or inactivated WSSV resulted in slower WSSV replication and delayed mortality. This evidence suggests a protective role of IHHNV as an interfering virus, while protection obtained by inactivated WSSV might result from non-specific antiviral immune response. 相似文献
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红螯螯虾感染白斑综合征病毒 总被引：2，自引：1，他引：2
红螯螯虾(Cherax quadricarinatus)是澳州淡水龙虾的一种,属甲壳纲、十足目、长尾亚目、拟螯虾科、光壳虾属,原产地澳大利亚,具有个体大、生长快、食性杂、易饲养等养殖性能优势;同时,因其肉味鲜美、富含低胆固醇蛋白质,是目前世界上较名贵的淡水经济虾之一。目前,美国、拉丁美 相似文献
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2000~2002年,应用光镜和电子显微技术对AVND发生期间栉孔扇贝(Chlamys farreri)各主要组织器官病理变化进行了连续观察。光镜观察显示,除生殖腺、闭壳肌外,濒死栉孔扇贝的外套膜、鳃、肾、消化腺和肠组织都有不同程度的组织病理变化。病灶主要出现在上述各器官的结缔组织以及上皮组织,病理变化表现为细胞核肿大、固缩、破裂,核染色质边缘化或空泡化,受感染细胞崩解、脱落,留下大片均质无结构的空白区域,形成凝固性坏死,结缔组织细胞质中有嗜碱性包涵体样颗粒存在。电镜观察显示,在病灶出现的组织细胞内,细胞核染色质异常凝集和边缘化、核膜周隙扩张或溶解。细胞器病理变化明显,内质网扩张,核糖体脱落,有髓鞘样小体出现;线粒体肿大、嵴融解,整个细胞出现解体现象。病变的结缔组织细胞与间质细胞细胞质中有大量直径为130~170nm、具有囊膜的球形病毒粒子存在,负染电镜观察表明,病毒囊膜表面覆有长20nm放射状纤突。病毒的发生基质在细胞质内,并被一膜性结构所包围。病毒在宿主细胞中的繁殖分为3个阶段,即病毒发生期、病毒装配期和病毒释放期。病理学观察证明,病毒感染与病理变化具有明显的相关性。 相似文献
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神经坏死病毒(nervous necrosis virus,NNV)是一种世界范围内流行、严重危害多种海水和淡水鱼类的传染性病原。NNV为单一正链、2节段RNA病毒,基因组由RNA1(3.1 kb)和RNA2(1.4 kb)组成。在病毒复制过程中,会合成亚基因组RNA3。RNA1编码RNA聚合酶。RNA2编码衣壳蛋白,为病毒的唯一结构蛋白。RNA3编码B1和B2两种非结构蛋白。根据病毒衣壳蛋白的基因序列,神经坏死病毒可以分成4种基因型,分别为拟鲹、红鳍东方鲀、条斑星鲽和赤点石斑神经坏死病毒基因型。但是,目前只发现A、B、C三种病毒血清型,A对应拟鲹神经坏死病毒基因型,B对应红鳍东方鲀神经坏死病毒基因型、C对应条斑星鲽神经坏死病毒和赤点石斑神经坏死病毒基因型。病毒存在垂直和水平两种传播途径,而且广泛分布于养殖和野生鱼类中。阻断病毒在野生与养殖鱼类之间的传播和开展新型鱼类疫苗研发是将来研究趋势。 相似文献
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Betanodavirus infections of teleost fish: a review 总被引：20，自引：0，他引：20
In the last decade betanodavirus infections have emerged as major constraints on the culture of marine fish in all parts of the world with the exception of the African continent. The occurrence of these infections appears to be a function of the number of species cultured and the intensity of culture. This has been further complicated by the promiscuous translocation of stock within and between countries. Great strides have been made in defining these agents and producing diagnostic techniques but much more remains to be done. Lack of knowledge of the epidemiology of the diseases caused by nodaviruses, except for vertical transmission of the pathogen in some species, has impeded the development of control measures but, even so, the measures identified to date have not been adequately implemented by producers with the result that catastrophic losses still occur on a regular basis. 相似文献
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Procedures for a viral replication in excised fin tissue (VREFT) assay were adapted to Pacific herring, Clupea pallasii, and optimized both to reduce processing time and to provide the greatest resolution between naïve herring and those previously exposed to viral haemorrhagic septicaemia virus (VHSV), Genogroup IVa. The optimized procedures included removal of the left pectoral fin from a euthanized fish, inoculation of the fin with >105 plaque‐forming units (PFU) mL?1 VHSV for 1 h, rinsing the fin in fresh medium six times to remove unadsorbed virions, incubation of the fin in fresh medium for 4 days and enumeration of the viral titre in a sample of the incubation medium by plaque assay. The optimized VREFT assay was effective at identifying the prior exposure history of laboratory‐reared Pacific herring to VHSV. The geometric mean VREFT value was significantly greater (P < 0.01) among naïve herring (1.2 × 103 PFU mL?1) than among groups that survived exposure to VHSV (1.0–2.9 × 102 PFU mL?1); additionally, the proportion of cultures with no detectable virus was significantly greater (P = 0.0002) among fish that survived exposure to VHSV (39–47%) than among naïve fish (3.3%). The optimized VREFT assay demonstrates promise for identifying VHSV exposure history and forecasting disease potential in populations of wild Pacific herring. 相似文献
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Viral haemorrhagic septicaemia (VHS) is a serious disease in several fish species. VHS is caused by the rhabdovirus viral haemorrhagic septicaemia virus (VHSV). To prevent spreading of the pathogen, it is important to use a fast, robust, sensitive and specific diagnostic tool to identify the infected fish. Traditional diagnosis based on isolation in cell culture followed by identification using, for example, ELISA is sensitive and specific but slow. By switching to RT‐PCR for surveillance and diagnosis of VHS the time needed before a correct diagnosis can be given will be considerably shortened and the need for maintaining expensive cell culture facilities reduced. Here we present the validation, according to OIE guidelines, of a sensitive and specific Taqman‐based real‐time RT‐PCR. The assay detects all isolates in a panel of 79 VHSV isolates covering all known genotypes and subtypes, with amplification efficiencies of approximately 100%. The analytical and diagnostic specificity of the real‐time RT‐PCR is close to 1, and the analytical and diagnostic sensitivity is comparable with traditional cell‐based methods. In conclusion, the presented real‐time RT‐PCR assay has the necessary qualities to be used as a VHSV surveillance tool on par with cell culture assays. 相似文献
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Protective immunity of sevenband grouper, Epinephelus septemfasciatus Thunberg, against experimental viral nervous necrosis 总被引：9，自引：0，他引：9
This paper describes the protective immune responses of sevenband grouper, Epinephelus septemfasciatus Thunberg, immunized with live piscine nodavirus, the causative agent of viral nervous necrosis (VNN), or the Escherichia coli – expressed recombinant coat protein. Nodavirus-neutralizing antibodies were detected at titres ranging from 1:158 to 1:1257 in serum of sevenband grouper which survived intramuscular injection with the virus, by a cell culture assay system. The virus-neutralizing ability of immune serum was also confirmed by injecting virus previously treated with serum into fish. This indicates establishment of acquired immunity in survivors and thus explains why survivors from natural infection are resistant to recurrence of the disease. Young sevenband grouper were immunized twice by intramuscular injections with the recombinant coat protein. Immunized fish produced neutralizing antibodies at high titres for at least 110 days and showed significantly lower mortalities in virus challenge tests. These results suggest the potential for vaccination against VNN in sevenband grouper, which is susceptible to piscine nodavirus at all life-stages. 相似文献
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A Gregory L A Munro M Snow K L Urquhart A G Murray R S Raynard 《Journal of fish diseases》2009,32(6):481-489
This study investigated infection dynamics of infectious salmon anaemia virus (ISAV) by conducting two experiments to examine minimum infective dose and viral shedding of ISAV. In terms of minimum infective dose, the high variability between replicate tanks and the relatively slow spread of infection through the population at 1 × 101 TCID50 mL−1 indicated this dose is approaching the minimum infective dose for ISAV in seawater salmon populations. A novel qPCR assay incorporating an influenza virus control standard with each seawater sample was developed that enabled the quantity of ISAV shed from infected populations to be estimated in values equivalent to viral titres. Viral shedding was first detected at 7 days post-challenge (5.8 × 10−2 TCID50 mL−1 kg−1 ) and rose to levels above the minimum infective dose (4.2 × 101 TCID50 mL−1 kg−1 ) on day 11 post-challenge, 2 days before mortalities in ISAV inoculated fish started. These results clearly demonstrate that a large viral shedding event occurs before death. Viral titres peaked at 7.0 × 101 TCID50 mL−1 kg−1 15 days post-infection. These data provide important information relevant to the management of ISA. 相似文献
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Susceptibility of cultured juveniles of several marine fish to the sevenband grouper nervous necrosis virus 总被引：4，自引：0，他引：4
Piscine nodaviruses (betanodaviruses) have been tentatively divided into four genotypes (SJNNV, RGNNV, TPNNV and BFNNV) and it is suggested that host specificity is different among these genotypes. In the present study, a betanodavirus [sevenband grouper nervous necrosis virus (SGNNV)] belonging to the redspotted grouper nervous necrosis virus (RGNNV) genotype, to which most betanodaviruses from warm water fish are identified, was evaluated for its pathogenicity to hatchery-reared juveniles of several marine fish species. When challenged with the virus by a bath method (10(5.1) TCID50 mL(-1)), sevenband grouper, Epinephelus septemfasciatus, Japanese flounder, Paralichthys olivaceus, and tiger puffer, Takifugu rubripes, displayed behavioural abnormalities and mortalities with distinct histopathological signs of viral nervous necrosis and heavily immunostained cells were observed in the central nervous tissues and retina. Bath-challenged rock fish, Sebastiscus marmoratus, and a hybrid of sevenband grouper and kelp grouper, E. moara, did not display any behavioural abnormality or mortality during the experimental period, although many fish showed slight signs of viral infection in nerve cells. Kelp grouper and red sea bream, Pagrus major, showed no behavioural abnormality, mortality or immunohistopathological changes after the virus challenge. These results are, in part, consistent with the natural host range of RGNNV, indicating the complexity in the host specificity of betanodaviruses. 相似文献
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R Pakingking Jr R Seron L dela Peña K Mori H Yamashita T Nakai 《Journal of fish diseases》2009,32(5):457-463
Asian sea bass, Lates calcarifer (Bloch), exhibited strong immune responses against a single injection of the formalin-inactivated red-spotted grouper nervous necrosis virus (RGNNV), a betanodavirus originally isolated in Japan. Fish produced neutralizing antibodies at high titre levels from days 10 (mean titre 1:480) to 116 (1:1280), with the highest titre at day 60 post-vaccination (1:4480). When fish were challenged with the homologous RGNNV at day 54 post-vaccination, there were no mortalities in both the vaccinated and unvaccinated control fish. However, a rapid clearance of the virus was observed in the brains and kidneys of vaccinated fish, followed by a significant increase in neutralizing-antibody titres. Furthermore, the vaccine-induced antibodies potently neutralized Philippine betanodavirus isolates (RGNNV) in a cross-neutralization assay. The present results indicate the potential of the formalin-inactivated RGNNV vaccine against viral nervous necrosis (VNN) of Asian seabass. 相似文献
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在病毒感染宿主细胞过程中,病毒利用宿主细胞骨架如微丝、微管等完成进入、运输和释放等过程。为分离鉴定石斑鱼虹彩病毒SGIV囊膜蛋白,实验应用去污剂溶解病毒囊膜,然后结合1-D-SDS-PAGE切胶分离和LC-MS/MS质谱鉴定两种方法进行检测,除了病毒编码的囊膜蛋白外,还发现7种宿主细胞来源的蛋白,包括细胞骨架微丝肌动蛋白actin等,由此推测这些宿主蛋白是与病毒纯化过程中共纯化获得。鉴于actin在病毒感染中发挥着重要的作用,进一步通过蛋白印迹、免疫电镜实验验证了actin与病毒共纯化,揭示actin是一种来源于宿主细胞并包装到病毒颗粒表面的宿主蛋白,且由于特异性作用黏附于病毒粒子表面,在分离病毒囊膜时与囊膜蛋白共纯化。此外,荧光显微镜观察发现,在病毒感染晚期,细胞变圆,细胞微丝actin蛋白和SGIV病毒共定位于细胞膜,提示actin与病毒释放相关。同时电镜观察也表明,病毒在感染细胞中释放时获得由宿主细胞质膜衍生而来的囊膜,由此推测actin可能在病毒释放时特异性包裹于SGIV病毒表面。研究表明,actin参与石斑鱼虹彩病毒SGIV的释放过程。 相似文献
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鱼病毒性神经坏死病病毒（VNNV）不同基因型鉴别方法的建立及在VNN检疫和监测中的应用 总被引：8，自引：3，他引：8
从GenBank中查找出乙型野田村病毒组中海水鱼类各病毒的序列,并用Sequencher多重序列比较软件将其分到条纹踢神经坏死病毒(striped jack nervous necrosis virus,SJNNV)组、条纹星鲽神经坏死病毒(barfin flounder nervous necrosis virus,BFNNV)组、红点石斑鱼神经坏死病毒(redspotted grouper nervous necrosis virus,RGNNV)组和虎斑东方纯神经坏死病毒(tiger puffer nervous necrosis virus,TPNNV)组4个基因型的组别中。用DNAsis序列比较软件比较同一基因型各基因序列之间的同源性,均在815％以上;不同基因型之间序列的同源性,均在66％以下。结合Premier引物设计软件和Sequencher序列多重比较软件,设计了4对引物,采用逆转录聚合酶链式反应(RT—PCR)来鉴别这4个不同的基因型。对从深圳口岸进境的产地为台湾的海水鱼苗和广东、福建两省养殖的主要海水鱼类进行检疫和监测,结果在进境的海水鱼苗中检出有RGNNV基因型的VNNV,在福建和广东省养殖的石斑鱼成鱼和鱼苗的病鱼体内均检测到RGNNV基因型的VNNV,对上述扩增产物基因序列进行比较,相似性均在96．5％以上,推导出的氨基酸序列与玛拉巴石斑鱼神经坏死病毒(MNNV)序列相似性均为100％。 相似文献