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1.
White leg shrimp, Penaeus vannamei, were collected on a monthly basis from grow‐out ponds located at Tamil Nadu and Andhra Pradesh states along the east coast of India for screening of viral and other pathogens. Totally 240 shrimp samples randomly collected from 92 farms were screened for white spot syndrome virus (WSSV), infectious hypodermal and haematopoietic necrosis virus (IHHNV), infectious myonecrosis virus (IMNV) and Enterocytozoon hepatopenaei (EHP). The number of shrimp collected from shrimp farms ranged from 6 to 20 based on the body weight of the shrimp. All the shrimp collected from one farm were pooled together for screening for pathogens by PCR assay. Among the samples screened, 28 samples were WSSV‐positive, one positive for IHHNV and 30 samples positive for EHP. Among the positive samples, four samples were found to be positive for both WSSV and EHP, which indicated that the shrimp had multiple infections with WSSV and EHP. This is the first report on the occurrence of multiple infections caused by WSSV and EHP. Multiplex PCR (m‐PCR) protocol was standardized to detect both pathogens simultaneously in single reaction instead of carrying out separate PCR for both pathogens. Using m‐PCR assay, naturally infected shrimp samples collected from field showed two prominent bands of 615 and 510 bp for WSSV and EHP, respectively.  相似文献   

2.
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3.
White spot syndrome (WSS) is considered as a great threat to commercial farming of the tiger shrimp (Penaeus monodon). The causal agent of WSS is a DNA virus called white spot syndrome virus (WSSV). The prevalence of this dreadful virus infection has been studied in five randomly selected hatcheries located in the Cox’s Bazar district of Bangladesh. Both one-step and nested polymerase chain reaction (PCR) involving two pairs of primers, namely, 146F1/146R1 and 146F2/146R2, amplifying the 1447 bp and 941 bp fragments, respectively, were conducted to detect the WSSV. Out of 60 randomly collected shrimps, 12 (20%) were found to be positive by one-step PCR, while 18 (30%) were found to be positive by nested PCR. The nested PCR was found to be much more sensitive than the one-step PCR. The shrimp specimens showing clinical signs of WSS were positive for WSSV by both one-step and nested PCR. Some of the apparently healthy samples were also found to be positive for WSSV by nested PCR. Among the two primer-pairs, the inner pair amplifying the 941 bp fragment was more sensitive than the outer primer pair amplifying the 1447 bp fragment when used in one-step PCR.  相似文献   

4.
White spot syndrome virus (WSSV) has caused significant losses in shrimp farms worldwide. Between 2004 and 2006, Pacific white shrimp Litopenaeus vannamei (Boone) were collected from 220 farms in Taiwan to determine the prevalence and impact of WSSV infection on the shrimp farm industry. Polymerase chain reaction (PCR) analysis detected WSSV in shrimp from 26% of farms. Juvenile shrimp farms had the highest infection levels (38%; 19/50 farms) and brooder shrimp farms had the lowest (5%; one of 20 farms). The average extent of infection at each farm was as follows for WSSV‐positive farms: post‐larvae farms, 71%; juvenile farms, 61%; subadult farms, 62%; adult farms, 49%; and brooder farms, 40%. Characteristic white spots, hypertrophied nuclei and basophilic viral inclusion bodies were found in the epithelia of gills and tail fans, appendages, cephalothorax and hepatopancreas, and virions of WSSV were observed. Of shrimp that had WSSV lesions, 100% had lesions on the cephalothorax, 96% in gills and tail fans, 91% on appendages and 17% in the hepatopancreas. WSSV was also detected in copepoda and crustaceans from the shrimp farms. Sequence comparison using the pms146 gene fragment of WSSV showed that isolates from the farms had 99.7–100% nucleotide sequence identity with four strains in the GenBank database – China ( AF332093 ), Taiwan ( AF440570 and U50923 ) and Thailand ( AF369029 ). This is the first broad study of WSSV infection in L. vannamei in Taiwan.  相似文献   

5.
对虾WSSV病是亚洲对虾养殖业中的一个棘手问题。本研究采用Kimura引物 ,用PCR技术对不同生长期的中国对虾 (Penaeuschinensis)进行了WSSV的检测 ,同时也检测了对虾发病时养殖池中多见的野生厚蟹 (Helicesp .)和矛尾刺虎鱼 (Acanthogobiushasta)。检测结果表明 :分别在检测的 5尾亲虾中的 1尾 ,6尾仔虾中的 1尾 ,5尾稚虾中的 3尾及所检测的 5尾病虾和 2只厚蟹中获得到 982bp的PCR扩增产物 ,说明为WSSV感染阳性。在检测的 2尾矛尾刺虎鱼中均未获得PCR扩增产物 ,说明为WSSV感染阴性。在亲虾、虾苗以及虾池内的野生厚蟹中检测到WSSV感染的阳性结果表明 :WSSV感染的亲虾有可能是病毒的储主 ,WSSV感染的野生厚蟹有可能是病毒中间宿主或病毒的携带者 ,它们在对虾WSSV病的感染、传播中起了重要的作用  相似文献   

6.
The objective of this study was to investigate the reason for variation in the virulence of white spot syndrome virus (WSSV) from different shrimp farms in the Southeast coast of India. Six isolates of WSSV from farms experiencing outbreaks (virulent WSSV; vWSSV) and three isolates of WSSV from farms that had infected shrimps but no outbreaks (non‐virulent WSSV; nvWSSV) were collected from different farms in the Southeast coast of India. The sampled animals were all positive for WSSV by first‐step PCR. The viral isolates were compared using histopathology, electron microscopy, SDS‐PAGE analysis of viral structural proteins, an in vivo infectivity experiment and sequence comparison of major structural protein VP28; there were no differences between isolates in these analyses. A significant observation was that the haemolymph protein profile of nvWSSV‐infected shrimps showed three extra polypeptide bands at 41, 33 and 24 kDa that were not found in the haemolymph protein profile of vWSSV‐infected shrimps. The data obtained in this study suggest that the observed difference in the virulence of WSSV may not be due to any change in the virus, rather it could be due to the shrimp defence system producing certain factors that help it to accommodate the virus without causing any mortality.  相似文献   

7.
应用PCR和RT-PCR技术对4种对虾病毒的检测   总被引：5，自引：3，他引：5  
探讨了应用PCR和RT－PCR技术对4种主要的对虾病毒进行检测的方法。同时使用该方法检测了对虾天然饵料－－卤虫中的4种对虾病毒。结果显示，含病毒核酸的阳性对照样品分别扩增出了大小为824bp,705bp,260bp和216bp的预期产物，但未能从卤虫样品中检测到此4种病毒的存在。本文报道的病毒检测方法具有快速、灵敏、准确的特点，可以用于进出口贸易中对活体或冰冻对虾，虾苗，对虾饵料等进行相关对虾病毒的检疫，也为制定我国对虾病毒检疫检验规范提供了技术参考。  相似文献   

8.
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9.
中国对虾几个产卵场群体携带白斑综合征病毒状况调查   总被引：5，自引：1，他引：4  
邓灯 《水产学报》2005,29(1):74-78
白斑综合征可以导致养殖对虾短时间内大面积死亡,是迄今为止对虾养殖业面临的最大挑战。本试验采用巢式PCR法对2001年采自黄渤海的中国对虾几个产卵场群体进行白斑综合征病毒检测,旨在较全面地了解黄渤海野生中国对虾携带病毒状况。各群体的阳性检出率分别为：朝鲜半岛南海岸群体55％;渤海湾群体35％;辽东湾群体94．7％;海州湾群体47．4％。结果显示,中国对虾几个产卵场群体均不同程度地携带白斑综合征病毒。辽东湾产卵场群体阳性检出率明显高于其他群体,推测人工孵化苗种放流、海湾的地理和水质条件与中国对虾的WSSV感染率相关。而中国对虾野生群体携带病毒对于对虾养殖业的影响是不容忽视的,笔者认为,只有从无特异病原(SPF)及抗特异病原(SPR)对虾养殖群体的建立着手才能从根本上避免由于对虾携带病毒而可能导致的病毒性疾病的暴发。同时,应该重视海区污染的治理,减少病毒病暴发的诱因。本试验建立了快速检测WSSV的PCR方法,1pg病毒核酸仍可检测到,为白斑综合征病毒病的防治及早期诊断提供了有效的手段。  相似文献   

10.
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11.
氨氮胁迫下白斑综合征病毒对凡纳滨对虾的致病性   总被引：1，自引：0，他引：1  
为了评价养殖水环境中氨氮(NH_4-N)对凡纳滨对虾(Litopenaeus vannamei)的危害性,开展了NH_4-N胁迫对凡纳滨对虾感染白斑综合征病毒(WSSV)后的死亡率、WSSV增殖速率和对虾主要免疫相关酶活性影响的实验。在NH_4-N胁迫质量浓度为15.6 mg·L-1,分别注射2×105和2×106个WSSV粒子,结果显示,NH_4-N胁迫下注射2×105个WSSV粒子的凡纳滨对虾第144小时死亡率达到53.3%,显著高于无胁迫组(40.0%)。对虾鳃组织WSSV荧光定量PCR检测结果显示,NH_4-N胁迫下凡纳滨对虾鳃组织内WSSV的增殖加快。此外,免疫相关酶活性结果显示,NH_4-N浓度突变会促使对虾血清中酚氧化酶(PO)、酸性磷酸酶(ACP)和碱性磷酸酶(AKP)活性短暂升高后持续降低。由此可见,NH_4-N胁迫会加快WSSV在患病凡纳滨对虾体内的增殖,导致更高死亡率,这可能是因为胁迫造成了对虾免疫相关酶活性降低和抗病原感染能力下降。  相似文献   

12.
The present work was performed to investigate if feeding Litopenaeus vannamei with microencapsulated thyme essential oil (TEM, 1.05 g thyme essential oil per 100-g powder) adsorbed on commercial pellet feed was able to protect shrimps against white spot syndrome virus (WSSV) disease. Five treatments were tested: uninfected shrimp fed with commercial pelleted feed (TC, negative control), WSSV-infected shrimp fed with commercial pelleted feed (T1, positive control), WSSV-infected shrimp fed with commercial pelleted feed with 0.1% TEM (T2), WSSV-infected shrimp fed with commercial pelleted feed with 0.5% TEM (T3), and WSSV-infected shrimp fed with commercial pelleted feed with 1% TEM (T4). At 72 h post infection, phenoloxidase activity of shrimps treated with 1% TEM did not show significant differences with TC values but it was significantly higher than that of the other treatments (T1, T2, and T3). Moreover, shrimps treated with T4 presented absence of clinical signs of WSSV infection and their survival rate was significantly higher than that of T1, T2, and T3 treatments. Therefore, 1% TEM seemed to protect shrimps against WSSV symptoms. Using microencapsulated thyme essential oil may help to fight against WSSV in shrimp farms.  相似文献   

13.
The rotifer Brachionus urceus (Linnaeus, 1758) was experimentally infected with the white spot syndrome virus (WSSV) by the virus-phytoplankton adhesion route in order to assess the possibility of rotifer acting as a vector of WSSV to infect the shrimp Fenneropenaeus chinensis (Osbeck, 1765) larvae at zoea stage III. The nested-PCR test revealed WSSV-positive results in the rotifers exposed to WSSV by the virus-phytoplankton adhesion route. Among 10 replicates in the infection treatment, 40% of F. chinensis larvae became WSSV-positive when fed with WSSV-positive rotifers, whereas all were WSSV-negative for F. chinensis when fed with WSSV-free rotifers. Though the mortality of shrimp larvae in the infection treatment (39.47 ± 15.44%) was higher than that in the control treatment (34.67 ± 15.11%), there was no significant difference in the mortality between them (P > 0.05). These results indicated that the rotifer could serve as a vector in WSSV transmission when ingested.  相似文献   

14.
杨卫帆  易小平 《水产科学》2006,25(12):649-651
采用对虾白斑综合症病毒和传染性皮下组织坏死病毒的特异引物,在一个PCR反应中同时扩增到大小分别为271 bp和356 bp的病毒特异片段,多重PCR条件优化后可从最少100 fg级病毒DNA模板中定性检测出此两种病毒。  相似文献   

15.
The protective effect of a probiotic mixture (PM) and antiviral plants, against the white spot syndrome virus (WSSV) in Litopenaeus vannamei , was evaluated in three experiments. The PM was composed of four lactic acid bacteria (LAB) and one yeast strain. The plant mixture was composed of Ocimum sanctum and commercial antiviral plants (VPH®, HSV®). Shrimp in each experiment (weighing 2.7±0.7, 11.5±1.3, 11.70±2.5 g) were cultured in 120-L plastic tanks and fed twice a day with commercial feed plus additives (plants or bacteria and yeast). Animals were monitored for the occurrence of WSSV by single-step and nested PCR. The PM and powdered antiviral plants added to the commercial feed showed an increase in survival and a decrease in the prevalence of WSSV in shrimp. The results showed that both the PM and the powdered antiviral plants can provide protection for shrimp against WSSV.  相似文献   

16.
在基础饲料中分别添加0.1%和1%美人鱼发光杆菌灭活菌、0.1%美人鱼发光杆菌活菌配制成3种免疫实验饲料,以基础饲料为空白对照组饲料,每组设3个平行样。对个体质量为(4.83±0.36)g的凡纳滨对虾进行为期20 d的饲养实验,分别在0、5、10、15和20d进行取样,以血清中的酚氧化酶(PO)、酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、超氧化物歧化酶(SOD)和溶菌酶(UL)活性为免疫指标,探讨了美人鱼发光杆菌作为免疫制剂对凡纳滨对虾非特异性免疫效应的影响;在投喂免疫饲料后的第22天,按0.004 2 kg/kg体重的剂量,直接投喂对虾白斑综合征病毒(WSSV)病料,并记录累积死亡率。结果表明,美人鱼发光杆菌免疫实验组对凡纳滨对虾血清中PO、ACP、AKP、UL和SOD活性影响明显高于对照组,并且在饲料中添加美人鱼发光杆菌后,明显提高了对虾抵御WSSV感染的能力。其中0.1%美人鱼发光杆菌活菌实验组的抗病毒感染能力最强,WSSV感染14d内累计死亡率为63.3%±5.8%;而对照组为96.7%±3.3%。研究表明,美人鱼发光杆菌添加在对虾饲料中能提高凡纳滨对虾非特异性免疫水平,增强抵抗疾病的能力,将其作为对虾免疫增强剂具有良好的应用前景。  相似文献   

17.
In recent years, the shrimp industry has turned to inland freshwater culture as one method to avoid problems such as the introduction of possible vectors of viral pathogens into seawater ponds. Our experiments evaluated susceptibility to white spot syndrome virus (WSSV) in Litopenaeus vannamei held under different salinity regimens. Juvenile L. vannamei that were conditioned at salinities of 35, 25, 15, 5 and 2 g L−1 were challenged with WSSV. In order to assess the severity of white spot disease, histological analysis and nested polymerase chain reaction (PCR) tests were carried out on the challenged shrimp every 4 h after 48 h post challenge. The results indicated that significantly more severe infections resulted at 15‰ than at other salinities. Mortality could not be compared due to the sampling design and because severe WSSV infections occurred in all test groups such that few shrimp remained alive in each challenged group at the end of the test. Despite this, the results suggest that salinity may affect the course and outcome of WSSV infections.  相似文献   

18.
White spot syndrome virus (WSSV) is the most important pathogen in shrimp farming systems worldwide including the Mekong Delta, Vietnam. The genome of WSSV is characterized by the presence of two major ‘indel regions’ found at ORF14/15 and ORF23/24 (WSSV‐Thailand) and three regions with variable number tandem repeats (VNTR) located in ORF75, ORF94 and ORF125. In the current study, we investigated whether or not the number of repeat units in the VNTRs correlates with virus outbreak status and/or shrimp farming practice. We analysed 662 WSSV samples from individual WSSV‐infected Penaeus monodon shrimp from 104 ponds collected from two important shrimp farming regions of the Mekong Delta: Ca Mau and Bac Lieu. Using this large data set and statistical analysis, we found that for ORF94 and ORF125, the mean number of repeat units (RUs) in VNTRs was significantly lower in disease outbreak ponds than in non‐outbreak ponds. Although a higher mean RU number was observed in the improved‐extensive system than in the rice‐shrimp or semi‐intensive systems, these differences were not significant. VNTR sequences are thus not only useful markers for studying WSSV genotypes and populations, but specific VNTR variants also correlate with disease outbreaks in shrimp farming systems.  相似文献   

19.
Since it first appeared in 1992, white spot syndrome virus (WSSV) has become the most threatening infectious agent in shrimp aquaculture. Within a decade, this pathogen has spread to all the main shrimp farming areas and has caused enormous economic losses amounting to more than seven billion US dollars. At present, biosecurity methods used to exclude pathogens in shrimp farms include disinfecting ponds and water, preventing the entrance of animals that may carry infectious agents and stocking ponds with specific pathogen-free post-larvae. The combination of these practices increases biosecurity in shrimp farming facilities and may contribute to reduce the risk of a WSSV outbreak. Although several control methods have shown some efficacy against WSSV under experimental conditions, no therapeutic products or strategies are available to effectively control WSSV in the field. Furthermore, differences in virulence and clinical outcome of WSSV infections have been reported. The sequencing and characterization of different strains of WSSV has begun to determine aspects of its biology, virulence and pathogenesis. Knowledge on these aspects is critical for developing effective control methods. The aim of this review is to present an update of the knowledge generated so far on different aspects of WSSV organization, morphogenesis, pathology and pathogenesis.  相似文献   

20.
以超低温保存的感染了白斑综合征病毒(WSSV)的中国对虾制备的病毒粗提液为毒种，注射感染凡纳对虾并收集濒死虾，DNA斑点杂交检测每尾凡纳对虾WSSV感染状况。取DNA斑点杂交呈强阳性的30尾对虾，平均分为3组，病毒粗提液也平均分成3组，3组材料分别通过^60Co辐照，辐照时间分别为12、24和36h，辐照剂量为0．8KGy／h。辐照后的材料经PCR检测证实^60Co辐照不能完全破坏WSSV的DNA组成。以辐照后的感染白斑综合征病毒的对虾个体和白斑综合征病毒粗提液为感染毒种，人工感染健康凡纳对虾，验证^60Co辐照对病毒感染力的破坏作用，证实^60Co辐照可显著降低WSSV病毒粗提液的感染力，^60Co辐照可适当降低WSSV感染对虾的感染力。  相似文献   

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