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1.
为研究溶藻弧菌鞭毛蛋白flaC基因DNA疫苗对红笛鲷的免疫保护作用,实验构建了重组真核表达质粒pcDNA-flaC并将该质粒肌肉注射红笛鲷,采用PCR、RT-PCR、ELISA和攻毒试验等方法检测了该真核表达质粒在红笛鲷组织内的分布、表达和对红笛鲷的免疫保护.PCR结果显示,免疫接种7和28 d,注射点周围肌肉、鳃、肾脏、肝脏和脾脏都存在质粒分布;RT-PCR结果显示,免疫接种后第7天、14天和28天,红笛鲷不同组织内均有目的基因表达.ELISA结果表明,鱼血清内产生了抗FlaC蛋白的抗体,表明DNA疫苗免疫后鱼体表达了目的蛋白,并诱导产生了相应抗体.攻毒实验表明,免疫后的红笛鲷能较好地抵抗致病性溶藻弧菌的感染.结果表明,质粒pcDNA-flaC可能是抵抗溶藻弧菌感染的有效的疫苗候选物.  相似文献   

2.
In the Mediterranean area, wild fish have often been suggested as either the reservoirs of the causative agents or at least the carriers of the pathogens responsible for disease outbreaks in cultured fish. However, no epidemiological investigations on actual pathogen/disease interactions between farmed and wild fish have been conducted even for the most important fish pathogens. Only sporadic isolations and identifications of various pathogens in wild fish have been done and real associations with the pathological conditions that exist within the farm environment and vice versa have not been established. Monogenean ectoparasite Sparicotyle chrysophrii and isopod Ceratothoa oestroides are commonly found in the Mediterranean cage-reared sea bream and sea bass and in the surrounding wild fish population. Both species were recognized as pathogens that seasonally inflict serious losses in fingerlings and juveniles of sea bream and sea bass, being potentially propagated and exchanged during wild and caged fish interaction. In order to evaluate the degree of pathogens transfer between wild and farmed fish, we investigated genetic population structures of these two important parasitic pathogens inferred by mtDNA cytochrome oxidase I locus. Parasites isolated from wild and farmed fish on the two most productive Adriatic fish farms showed genetic heterogeneity, contradicting widely accepted hypothesis of cross-contamination, at least in case of S. chrysophrii and C. oestroides. As far as we know, this is the first report that in a study of pathogen transfer molecular evidence was employed to asses the genetic population structure of shared parasites.  相似文献   

3.
A comparative study of the efficacy of two vaccine formulations, a whole-cell bacterin (WCB) and a toxoid-enriched whole-cell vaccine (WCEB), against Pasteurella piscicida was conducted by bath immersion in gilthead seabream in order to evaluate the role of the extracellular products (ECP) as protective antigens against this pathogen. With this aim, two strains showing differences in their ECP composition were used to prepare both vaccines. Only the toxoid-enriched vaccine conferred protection against P. piscicida within a 4-week period. The relative percent survival (RPS) acheived with this type of vaccine ranged between 37 and 41 depending on the bacterial strain and dose used in the challenge. Although this protection level is not very high, we consider that it is valuable considering the economic importance of the fish susceptible to pasteurellosis throughout the world. The booster immunization with the WCEB P. piscicida formulation did not increase the protection levels of gilthead seabream. The antibody response in the sera of both immunized fish groups was very low with no correlation between the level of agglutinating antibodies and the protection. In addition, this vaccine did not confer cross-protection against serotypes 01 and 02 of Vibrio anguillarum.  相似文献   

4.
Galaxias maculatus, the common jollytail, is a native smelt fish with a lacustrine or diadromous life cycle. In Chile, the rearing cycle of this fish includes a freshwater and a marine phase. Several diseases and parasites reported for the freshwater phase could be avoided by rearing the fish in salty or brackish water. Nonetheless, this alternative could result in Caligus rogercresseyi infections. The objective of this study was to evaluate experimentally the capacity of C. rogercresseyi to infect the common jollytail and the effects this parasite may cause to the fish. Prevalence and intensity of experimental C. rogercresseyi infections on G. maculatus were estimated and the effects of this parasitosis on the fish were evaluated on fish survival, weight loss, swimming behavior, and skin damage. Two experiments were carried out with adult fish taken from the Maullín Estuary. Fish were acclimatized to a salinity of 32 ppt and divided into two groups of 20 fish each. The experimental group was infected with copepodid stages of C. rogercresseyi and the other was used as a control. The fish were kept in individual tanks until observing ovigerous female copepods. C. rogercresseyi recognizes G. maculatus as a host under experimental conditions and optimal salinity for the parasite. Results show that under experimental condition copepodid stage can successfully infect the fish, developing to the adult stage, mating, and producing eggs (females). C. rogercresseyi caused alterations in fish behavior, superficial body damage, weight loss, and mortality. Rearing the common jollytail in salty water should take into consideration measures to control these infections as they can damage fish and affect surrounding wild fish populations. There are no records of this parasite in natural common jollytail populations; however, our understanding of the ecological role played by the common jollytail in C. rogercresseyi transmissions among sympatric host species could be greatly improved through further research related to host preferences and epidemiological data for different sympatric host species.  相似文献   

5.
An outbreak of disease characterized by skin ulcers, fin rot and mortality was observed a few days after the transfer of Atlantic salmon (Salmo salar) from a freshwater smolt production facility to a land‐based seawater post‐smolt site. Dead and moribund fish had severe skin and muscle ulcers, often 2–6 cm wide, particularly caudal to the pectoral fins. Microscopic examination of smears from ulcers and head kidney identified long, slender Gram‐negative rods. Histopathological analysis revealed abundance of long, slender Tenacibaculum‐like bacteria in ulcers and affected fins. Genetic characterization using multilocus sequence analysis (MLSA) of seven housekeeping genes, including atpA, dnaK, glyA, gyrB, infB, rlmN and tgt, revealed that the isolates obtained during the outbreak were all clustered with the Tenacibaculum dicentrarchi‐type strain (USC39/09T) from Spain. Two bath challenge experiments with Atlantic salmon and an isolate of T. dicentrarchi from the outbreak were performed. No disease or mortality was observed in the first trial. In the second trial with a higher challenge dose of T. dicentrarchi and longer challenge time, we got 100% mortality within 48 hr. This is the first reported outbreak of disease caused by T. dicentrarchi in Norwegian farmed Atlantic salmon.  相似文献   

6.
A disease outbreak occurred in swimming crab (Portunus trituberculatus) farmed in eastern China, with a mortality rate of more than 80%. To further investigate the characteristics and pathogenesis, we reported isolation, characterization and virulence of the causative agent of this disease from 10 sick crabs. Histopathological observation found that multiple tissues, especially haemolymph, contained lots of ciliates. The ciliate was isolated and cultured in vitro, and molecular and morphological studies were done. The results showed that SSU rDNA and LSU rDNA sequences of the ciliate were similar to Mesanophrys ciliates (>96.81%), while ITS1-5.8s-ITS2 sequence was similar to Mesanophrys pugettensis (95.37%) and identical to Orchitophrya stellarum (100%). Furthermore, the results of the morphological study confirmed that the ciliate was similar to Mesanophrys ciliates and O. stellarum cultured in supportive media, but different from O. stellarum cultured in living sperm cells of starfish (Leptasterias spp.). Also, the growth of the ciliate did not interfere with light, which was different from O. stellarum. Accordingly, the ciliate was classified as genus Mesanophrys and temporarily named as Mesanophrys sp. In addition, experimental infection confirmed that Mesanophrys sp. was the pathogen that infected farmed crabs. In summary, Mesanophrys sp. was first isolated and characterized in P. trituberculatus.  相似文献   

7.
A candidate vaccine against Aeromonas hydrophila in rainbow trout, Oncorhynchus mykiss, was developed using a bacterial lysate. To test the strength of protection, A. hydrophila challenge models were compared using injection into both the intraperitoneal (IP) cavity and the dorsal sinus (DS) with selected doses of live bacteria washed in saline or left untreated. Unlike the IP route, injection into the DS with either saline washed or unwashed cells resulted in consistent cumulative mortality and a dose response that could be used to establish a standard challenge having an LD50 of approximately 3 × 107 colony forming units per fish. Survivors of the challenge suffered significantly lower mortality upon re‐challenge than naïve fish, suggesting a high level of acquired resistance was elicited by infection. Passive immunization using serum from hyper‐immunized fish also resulted in significantly reduced mortality indicating protection can be transferred and that some portion of resistance may be antibody mediated. Vaccination of groups of rainbow trout with A. hydrophila lysate resulted in significant protection against a high challenge dose but only when injected along with Freund’s complete adjuvant. At a low challenge dose, mortality in all groups was low, but the bacterial lysate alone appeared to offer some protection.  相似文献   

8.
大黄蒽醌提取物对罗氏沼虾抗鳗弧菌感染的研究   总被引：4，自引：3，他引：1  
苏永腾  刘波  周群兰 《水产学报》2008,32(3):455-463
将罗氏沼虾随机分成5组,每组三个平行,每个平行约1000尾(个体均重1g左右),第1组为对照组,投喂基础日粮,另外4组为试验组,在基础日粮中分别添加0.05%、0.1%、0.2%、0.4%大黄蒽醌提取物,饲养6周后对罗氏沼虾进行鳗弧菌(Vibrio anguillarum)感染.测定生长以及0、12、24、48h血清和肝胰腺溶菌酶、丙二醛(MDA)、总抗氧化能(T-AOC)以及超氧化物歧化酶(SOD)等指标.生长试验表明,与对照组相比,0.1%组、0.4%组罗氏沼虾的增重率、特定生长率显著提高,饵料系数显著降低.攻毒试验Ⅰ表明,各组48h内罗氏沼虾血清溶菌酶活性、肝胰腺溶菌酶含量、血清T-AOC均呈先升高后降低趋势,其中它们的最大值分别出现于0.4%组的12h、0.2%组24h、0.1%组12h;肝胰腺SOD活力呈上升趋势,而血清MDA则一直下降.攻毒试验Ⅱ表明,大黄蒽醌提取物能有效地降低试验组罗氏沼虾的死亡率,提高免疫保护率,其中0.4%组的保护效果为最佳.因此,在饲料中添加大黄蒽醌提取物降低罗氏沼虾对病原的敏感性,增强机体抗病力,促进生长.  相似文献   

9.
用血卵涡鞭虫可溶性抗原免疫BALB/c小鼠,经常规融合、间接ELISA方法筛选,将所得阳性克隆再经3次亚克隆后,共获得3株针对血卵涡鞭虫的单克隆抗体(2B2、3G4、4G7),单克隆抗体亚类鉴定表明,三者为IgG类抗体。用筛选的杂交瘤细胞株制备小鼠腹水抗体,其细胞上清及腹水效价分别为5.12×10-4和8.00×10-4。进一步利用单克隆抗体建立间接荧光抗体方法对单抗特异性进行鉴定,阳性虫体被染上黄绿色荧光,而正常梭子蟹血淋巴则未被染色。用单克隆抗体和多克隆兔抗血清以羊抗鼠HRP-IgG为酶标抗体,建立了检测血卵涡鞭虫的双抗体夹心ELISA方法,该方法对血卵涡鞭虫阳性标本检测符合率为100%。结果表明,制备的单克隆抗体效价高、特异性好,可用于血卵涡鞭虫的早期临床诊断。  相似文献   

10.
为了探讨急性氨氮胁迫对黄颡鱼组织中抗氧化酶活性及HSP70和HSP90基因mRNA表达水平的影响,实验随机挑选了360尾黄颡鱼[初体质量(17.25±0.05)g],分别暴露于含有0(对照)、5.70(低浓度组)、28.50(中浓度组)和57.00(高浓度组)mg/L总氨氮浓度的水体中,进行96 h的急性胁迫实验。实验开始后,分别于0、12、24、48和96 h取样。结果显示,氨氮胁迫发生后,低、中浓度组实验鱼肝脏中超氧化物歧化酶(SOD)活性呈先升高后降低趋势,而高浓度组则持续降低;低、中、高浓度组实验鱼肝脏中丙二醛(MDA)含量在胁迫开始后显著升高;3 h时,高浓度组实验鱼肝脏中SOD活性达到最低,而MDA含量最高;24 h后,高浓度组实验鱼肝脏中过氧化氢酶(CAT)活性显著升高;低、中、高浓度组实验鱼肝脏中HSP70基因的mRNA表达量呈先降低后升高趋势,而鳃中HSP70基因表达量持续升高,但脑中HSP70基因在0 h后显著降低;氨氮胁迫3 h时,低、中、高浓度组实验鱼肝脏和脑中HSP70基因表达量显著低于对照组,而在鳃中正好相反;相比HSP70基因,高氨氮浓度组实验鱼肝脏和鳃中HSP90基因的mRNA表达量在24 h时达到最高。研究表明,不同浓度的氨氮胁迫会对黄颡鱼抗氧化酶活性造成不同程度的抑制,原因与丙二醛的积累量有关;相比HSP90基因,黄颡鱼HSP70基因的表达量在氨氮胁迫发生后迅速上调,这种生理调控机制提示HSP70在应对急性氨氮胁迫时发挥着更重要的作用。  相似文献   

11.
This study investigated the effects of the dietary intake of live yeast Debaryomyces hansenii (CBS 8339) on the immune response of juvenile leopard groupers Mycteroperca rosacea and on their resistance to infection by dinoflagellates Amyloodinium ocellatum.During 4 weeks, juvenile groupers were fed either a diet supplemented with D. hansenii at 106 cfu g− 1 or a control diet. Both groups were then transferred to a system infected with A. ocellatum and maintained in this stressful environment, for one week. Rearing conditions were favorable to the proliferation of the dinoflagellate and, at 7 days post-infection, the cumulative mortality rate of the control group was 89.5%, suggesting that the yeast-enriched diet conferred protection against the parasite. Only fish with yeast-supplemented diet recovered from the A. ocellatum challenge.The immunological response of both groups of fish was evaluated. Samples were collected at weeks 4 (stressed fish) and 7 (recovering fish) to determine the levels of hemoglobin, plasmatic protein, and immunoglobulin M (IgM) as well as the activity of antioxidant enzymes (SOD and CAT). IgM increased significantly (P ≤ 0.05) in the recovering fish, which had all been fed the yeast diet. A significantly increase was also observed in superoxide dismutase activity in juvenile fish fed the yeast diet; however catalase activity was not affected by the dietary yeast supplement. Overall, fish that received the yeast supplement in their diet have an enhanced immune response as compared with their control counterparts. The present results show that a diet supplemented with D. hansenii stimulates the immune system of juvenile M. rosacea thus enhancing their resistance against A. ocellatum.  相似文献   

12.
Ide, Leuciscus idus, breeders in Polish fish farm are cultured or are collected from the wild. The data about differences in reproduction of different ide forms in captivity are limited. In the present paper domesticated and wild stock are reproduced artificially. Cultured fish do not require application of spawning agents. For obtaining good-quality oocytes only stimulation with temperature and photoperiod is necessary.  相似文献   

13.
A challenge test against Aeromonas hydrophila was conducted using 2062 rohu carp (Labeo rohita) fingerlings obtained from 52 dams and 87 sires (87 full-sib families) of two year-classes (2003 and 2004). Attempts to establish a cohabitant challenge model were not successful. Therefore, fish were challenged by intraperitoneal injection with A. hydrophila in two replicate tanks per year-class, and dead fish were collected hourly. The mortality reached its peak at 16–22 h after challenge and had almost completely stopped after 58 h. The test was terminated after 382 h at which the average survival was 43.9 and 48.9% in the two 2003 year-class tanks, and 77.1 and 35.8% in the two 2004 year-class tanks. Heritability estimates for survival were obtained from sire and dam threshold models (THR) and sire and dam linear repeatability models (LINR). For both types of models the heritability estimates based on data from single tanks were not consistent. For both year-classes, data from one of the two challenged tanks demonstrated significant additive genetic variation in survival during the A. hydrophila infection, whereas the heritability estimates were not significantly different from zero for the other tank. Further, genetic correlation between survivals in the two replicate tanks in each year-class was not significantly different from zero. The differential results from the replicate tanks demonstrate that additional challenge test experiments are needed before firm conclusions can be drawn about the magnitude of additive genetic variation for survival to aeromonasis in rohu carp. A cohabitant challenge model that allows the testing of important defence mechanisms in the skin and mucous membranes of the fish might have been more appropriate. To establish a valid cohabitant challenge model for rohu carp should be given high priority.  相似文献   

14.
为建立大黄鱼肿大细胞病毒的培养方法,明确其分类地位,用肿大细胞病毒检测呈阳性的大黄鱼幼鱼病料 (FD201807和SA201808)肾组织匀浆液感染鳜仔鱼细胞系 (mandarin fish fry cell line-1,MFF-1)并连续传代,从病料组织匀浆液和细胞冻融液中提取病毒DNA,克隆病毒主要衣壳蛋白基因 (mcp),测序后与NCBI GenBank中的虹彩病毒科肿大细胞病毒属病毒mcp以及2018—2020年所检出的15株大黄鱼肿大细胞病毒mcp进行比对分析。结果显示,病毒传至第4代才可引起MFF-1细胞病变,细胞病变的主要特征为细胞脱壁、变圆、折光度增强;感染时间越长脱壁细胞越多,同时培养液中的颗粒增加;透射电镜下可见感染细胞的细胞质散在大小为130~150 nm的六边形病毒粒子和空壳。感染细胞的病变周期随传代代次的增加而缩短,第15代次的FD201807株感染细胞80%细胞病变的时间为3 d,第15代次的SA201808株感染细胞80%细胞病变的时间为7~8 d。mcp序列比对和聚类分析发现,SA201808株与FD201807株的mcp序列存在21个碱基差异,二者的mcp序列分别与大黄鱼虹彩病毒(large yellow croaker iridovirus, LYCIV) LYCIV-Zhoushan (GenBank: MW139932.1)和花鲈虹彩病毒 (Lateolabrax maculatus iridovirus, LMIV) (GenBank: MH577517.1)相近。15株从大黄鱼病料检出的肿大细胞病毒中,12株的mcp序列与SA201808株聚类;3株与FD201807聚类。本研究利用MFF-1细胞系分离培养了大黄鱼肿大细胞病毒,揭示了大黄鱼肿大细胞病毒存在差异,为更好地了解大黄鱼肿大细胞病毒提供了数据参考。  相似文献   

15.
为探究武汉单极虫病疾病过程和病理变化等特点,根据患病异育银鲫体表孢囊内有无成熟孢子和成熟孢子的崩溶解程度,将该病划分为发生、发展、消退和消失4个疾病时期,并分别进行病理变化观察和巢式PCR分析。结果发现,发生期的病鱼体表刚形成的孢囊使鳞片和皮肤微微隆起,孢囊乳白色,孢囊内分布着正在繁育逐渐增多的营养体,尚未出现成熟孢子;发展期的病鱼孢囊内已出现成熟孢子,孢囊逐渐增多增大,其表面黑色素细胞增加而呈灰黑色,感染强度高的病鱼出现死亡或畸形;消退期的成熟孢子通过破裂孢囊流入水体或不同步地崩溶解而减少直至全部溶解,孢囊随之逐渐缩小,使得黑色素细胞更为密集,此时期病鱼病情减轻不再出现死亡现象;消失期的病鱼孢囊平坦,内已无成熟孢子,只残留逐渐减少的成熟孢子崩溶解物质,黑色素细胞逐渐减少,最后原孢囊部位被结缔组织取代。巢式PCR分析结果表明,巢式第一轮和第二轮PCR在4个疾病时期都分别能扩增出1 584和853 bp的武汉单极虫目的条带,但在消失期的后期只有巢式第二轮PCR扩增出853 bp目的条带,说明残留的核酸物质含量逐渐减少,10月下旬后原孢囊部位巢式PCR扩增已无条带出现。本研究不仅揭示了武汉单极虫寄生部位在4个疾病时期的病理变化特点,而且明确了疾病消退和消失的2种方式,孢囊内成熟孢子通过破裂孢囊进入水体的方式和首次发现的孢囊内成熟孢子通过崩溶解的方式。  相似文献   

16.
Fish iridovirus causes systemic disease with high morbidity and mortality in various species of wild and farm‐raised fish, resulting in severe economic losses. Recently, frequent outbreaks of iridovirus infection have occurred among cultured fish in many Asian countries, emphasizing the need for a protective vaccine programme or the development of a suitable therapy. In this study, we expressed a recombinant major capsid protein (rMCP) of rock bream iridovirus (RBIV) from yeast using codon optimization. The rMCP in yeast was added to feed in an attempt to induce intestinal mucosal immunity for protection against and/or to reduce the severity of fish iridovirus infection. We found that fish immunized orally with rMCP underwent a successful induction of antibodies (P < 0.05) and were protected (P = 0.0001) against viral challenge. Based upon these results, oral administration of immunogenic protein as an antigen can be considered a useful method for implementation of vaccine programmes against iridovirus as well as other marine viral diseases.  相似文献   

17.
克氏原螯虾染色体及其核型   总被引：2，自引：1，他引：1  
张莎  俞树惠  邱高峰 《水产学报》2018,42(10):1513-1519
染色体是遗传物质的载体,是研究细胞遗传学的基础,为研究克氏原螯虾染色体及其核型,实验以性未成熟雄性个体的精巢为材料,采用低渗和空气干燥常规方法制备细胞分裂中期染色体标本,研究了克氏原螯虾染色体及核型。Giemsa和DAPI染色后在显微镜下观察到清晰的精母细胞减数分裂中期二价体和精原细胞有丝分裂中期染色体时相。对减数分裂中期二价体及有丝分裂中期染色体进行了数目上的统计。结果显示,克氏原螯虾二倍与单倍染色体数目分别为2N=188和N=94。由于有丝分裂染色体形状微小,核型分析困难,故选取减数分裂中期二价体,根据长度及着丝点位置对其进行了初步核型分析,核型公式为N=55M+22(SM,ST)+17T,未发现异形性染色体。  相似文献   

18.
Vaccination strategies have traditionally been used as preventative or prophylactic measures against disease (prophylactic immunization) in uninfected fish. Alternatively, therapeutic or remedial measures, such as antibiotic administration, are commonly employed to treat disease in infected fish. Vaccination as a therapeutic measure (therapeutic immunization), however, has not been adequately explored in sub‐clinically infected fish. Therapeutic and prophylactic immunization with three Streptococcus iniae vaccines, formalin‐killed whole S. iniae cells (FKC vaccine), concentrated S. iniae extracellular products (greater than 2 kDa) (ECP vaccine) and a combination of killed cells and extracellular products (FKC+ECP vaccine), were tested in hybrid striped bass, Morone chrysops×Morone saxatilis, previously naturally infected with S. iniae. Fish (mean weight 10.0 g) were injected intraperitoneally (IP) or intramuscularly (IM) with one of each of the vaccines, tryptic soy broth (TSB‐control) or non‐injected (non‐injected control) to evaluate therapeutic effects (Trial 1). Survivors of the natural infection and ECP and FKC+ECP vaccine immunization and another lot of non‐injected control fish were immersion challenged with 1.47 × 106 CFU of S. iniae mL?1 at 44 days post‐immunization to evaluate vaccine efficacy (Trial 2). Hybrid striped bass (1.0 g) were also IM injected with S. iniae ECP vaccine at an aquaculture facility and immersion challenged with 1.47 × 106 CFU of S. iniae mL?1 12 weeks post‐immunization (Trial 3). The ECP and FKC+ECP vaccines, regardless of injection route, significantly (P<0.001) increased survival in asymptomatic, sub‐clinically infected fish thereby providing therapeutic merit. Hybrid bass immunized IP or IM had mean per cent survival values ranging from 78 to 96 at 44 days post‐immunization (Trial 1) and 69–97 post challenge (Trial 2). Survival of fish injected with TSB or immunized with FKC vaccine was significantly lowered and ranged from 12 to 13 by IP injection and 40 to 50 by IM injection and thus, the FKC vaccine had no therapeutic effect. The survival of hybrid striped bass IM immunized with S. iniae ECP vaccine in field Trial 3 was 91 and the RPS was 83. These results demonstrate that therapeutic immunization using S. iniae ECP and FKC+ECP vaccines can control a natural S. iniae infection. Furthermore, S. iniae ECP or FKC+ECP vaccines can also be used prophylacticly to protect hybrid striped bass against subsequent pathogen challenge.  相似文献   

19.
引起混养塘中异育银鲫和鲢发病死亡的病原及组织病理   总被引：1，自引：1，他引：0  
混养的异育银鲫和鲢鱼种大批死亡,为明确发病死亡的病原和组织损伤并提供相关的疾病防控措施,进行了病鱼肉眼和显微镜检查、细菌学检测、病毒学检测、组织病理和药敏试验研究。结果发现,除在患病鱼体表偶然发现有少量不会引起充血等症状的杯体虫和车轮虫外,未在体内外发现其他寄生虫和真菌类病原;通过细菌分离、人工回感试验、生理生化特性和16S r RNA基因序列分析,从患病异育银鲫和鲢分离到的致病菌株均为嗜水气单胞菌;根据异育银鲫和鲢病毒性疾病的现状,使用鲤疱疹病毒2型(Cyprinid herpesvirus 2,Cy HV-2)DNA聚合酶基因的特异性引物分别对自然发病的异育银鲫和鲢进行PCR检测,只有异育银鲫检测到Cy HV-2,分别用它们的除菌组织上清液进行人工感染试验,只有异育银鲫出现充血症状和死亡现象;由此得出嗜水气单胞菌是异育银鲫和鲢发病死亡的主要病原,Cy HV-2是异育银鲫混合感染的次要病原。患病鲢与患病异育银鲫呈现出类似的组织病理现象,又有一些各自特有的组织病理表现,单纯细菌感染的鲢轻度病变以细胞颗粒变性为主,坏死细胞以核溶解为主,细菌和病毒混合感染的异育银鲫肝脏轻度病变以细胞滴状玻璃样变的变性为主,坏死组织细胞以核固缩和核碎裂为主,在肾脏和脾脏出现染色质边集于核膜的肿大细胞核,主要组织器官出现从变性到坏死的病理变化过程,最终失去应有的功能而死亡。依据药敏试验结果,建议内服诺氟沙星和氟苯尼考等抗生素防治本病的嗜水气单胞菌感染,混合感染Cy HV-2的异育银鲫可以通过注射Cy HV-2疫苗和生态养殖的方法控制和减少该病毒病感染和发展。  相似文献   

20.
Body abnormalities constitute an important problem to fish aquaculture. Pigmentation, scale and skeleton abnormalities have been reported in different cultured fish species. Environmental and genetic factors or their interaction have been suggested to explain their origin. Gilthead seabream (Sparus aurata) is one of the most important European cultured species. Lordosis and lack of operculum are common abnormalities in this species, and can reach frequency of 80% or more of commercial batches. In spite of an important body of data suggesting environmental factors related with their origin, scarce and not conclusive genetic data have been reported to date. In our study, a large number of families originating from the usual production process of a commercial farm were used to estimate the heritabilities of both characters. Two independent experiments were carried out for each abnormality. Nine hundred and ninety four (5.6% lordotics; 157 full-sib families; 6.3 offspring/family) and 808 (7.9% lacking operculum; 83 families; 9.7 offspring/family) individuals were used for lordosis and lacking operculum heritability estimations, respectively. The results obtained adjusting an animal model indicated non significant heritabilities for both characters (0.021 (s.e. 0.019) and 0.032 (s.e. 0.023) for lordosis and lack of operculum, respectively). The corresponding values when a threshold model was used, though higher (0.152 and 0.203, respectively), evidenced large standard errors (0.119 and 0.146, respectively) suggesting h2 = 0 as the most confident hypothesis (P = 0.838 and 0.766, respectively). A non-parametric permutation test was also applied to evaluate if more related individuals had a higher phenotypic resemblance. The results obtained suggested only a slight familiar association (P < 0.05) when comparing individuals lacking operculum, but neither between lordotics nor between normal ones. These results suggest that most phenotypic variation observed for lordosis and lack of operculum in gilthead seabream is due to environmental factors.  相似文献   

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