海水养殖真鲷最小弧菌外毒素的免疫学特性初步研究

按常规方法免疫健康家兔进行外毒素抗体的制备。将制备的兔抗血清与等体积的外毒素混合,37℃下作用1h后,观察毒素的溶血性及细胞毒性,取免疫前家兔血清(零号血清)作阴性对照,用毒素作阳性对照。结果表明,兔抗毒素血清能中和毒素,抑制毒素对人血细胞的溶血性及对Vero细胞的细胞毒性,中和毒素的兔抗毒素血清最高稀释度为1∶256,毒素对照显示出溶血性及细胞毒性。毒素与一定浓度的嗜水气单胞菌HEC毒素抗血清、霍乱肠毒素抗血清在37℃下分别作用1 h后,观察其溶血性及细胞毒性。结果表明,这2种抗血清都不能中和毒素,毒素与这2种抗血清作用后,仍然保持其溶血性及细胞毒性。用浓度为0.2%的福尔马林对浓度为5mg/mL的外毒素进行灭活处理,得到的灭活疫苗为毒素苗。一定稀释度的毒素苗,在初次免疫真鲷2周后利用病原菌对免疫组及对照组的实验鱼进行人工攻毒感染,毒素苗的免疫保护率可达80%,强化免疫后,免疫保护率有所提高。注射免疫的免疫保护率比浸泡免疫的高。     

基于原核表达的副溶血性弧菌类毒素疫苗对海水鱼类免疫保护作用

目的:实现副溶血性弧菌溶血毒素基因tdh克隆与表达,并以表达产物TDH作免疫原,研究其对海水鱼免疫活性的影响.方法:PCR扩增tdh;构建重组质粒(pET-28-TDH);IPTG诱导表达;SDS-PAGE检测:以纯化的TDH融合蛋白脱毒为类毒素免疫原免疫健康真鲷,测定其血清中过氧化氢酶(CAT)、酸性磷酸酶(ACP)、超氧化物歧化酶(SOD)和碱性磷酸酶(AKP)活性变化;用副溶血性弧菌病原攻毒,检测免疫保护作用.结果:tdh基因成功克隆并表达;表达蛋白相对分子量为21 kDa,证实为TDH蛋白;类毒素免疫真鲷后,其血清中总超氧化物歧化酶(T- SOD)、酸性磷酸酶(ACP)、碱性磷酸酶(AKP)和过氧化氢酶(CAT)活力在注射后48h、24h、24h、2Ah达到最高,最高点分别高于对照组77％、328％、75％、381％;72 h后均恢复至对照组水平.结论:类毒素对真鲷免疫系统具有明显的刺激作用;类毒素免疫后对攻毒的真鲷保护率达50％.     

三种创伤弧菌免疫原的制备及其对黄姑鱼的免疫保护效果

从创伤弧菌(Vibrio vulnificus)中提取菌体脂多糖(lipopolysaccaride,LPS)和外膜蛋白(outer membrane protein,OMP)并制备福尔马林灭活全菌苗(FKC),腹腔注射接种黄姑鱼。分别在注射第0、7、14、21和28天后测定了受免鱼血清中凝集抗体效价、血清溶菌酶活性和血液白细胞吞噬活性,以及免疫28d后的相对免疫保护率。结果表明,3种抗原对黄姑鱼均有较强的免疫原性。免疫后,免疫组血清凝集抗体效价逐渐增高,第28天时最高;溶菌酶活性(LMZ)、白细胞吞噬活性(PP)和吞噬指数(PI)显著升高(P<0.01),第21天达到峰值,随后逐渐下降。各组之间比较表明,受免后7、14、21和28d,免疫组黄姑鱼凝集抗体效价、PP、PI和LMZ显著高于对照组(P<0.05),LPS和OMP组凝集抗体效价低于FKC组,LPS和OMP组的相对免疫保护率高于FKC组,各组间免疫保护率大小顺序为LPS组>OMP组>FKC组>对照组。     

中草药复方对拟态弧菌的体内外抗菌和拮抗外毒素的作用

目的探明拟态弧菌外毒素的致病性,筛选出对拟态弧菌具有良好抗菌和拮抗外毒素作用的中草药复方。方法培养拟态弧菌安徽分离株,采用蛋白分离技术提取其外毒素,测定其对实验草鱼的致病性。以黄连、大黄、金银花、夏枯草、丹皮、地锦草、连翘、茯苓、车前子、黄芪和甘草组成3个复方,采用改良微量稀释法测定不同中草药复方对拟态弧菌的体外抑菌作用。同时使用动物模型测定不同中草药复方拮抗外毒素作用和对拟态弧菌感染草鱼的保护作用。结果4株拟态弧菌产生的外毒素对实验鱼均具有较强的致死性。复方3的体外抑菌作用最强,对4株拟态弧菌的MIC值均为1.96g/L;其次为复方1,其MIC值介于3.92～7.84g/L;复方2的抑菌作用最差,其MIC值介于62.72～125g/L。复方3拮抗外毒素作用最强,其次为复方2,复方1不具有抗毒素作用。复方3对拟态弧菌感染草鱼具有最好的保护作用,保护率为100%;其次为复方2,保护率为23.81%;复方1的保护率最低,仅为19.05%。结论拟态弧菌外毒素在腹水病发生过程中起着重要致病作用。复方3具有良好的抗菌和拮抗外毒素作用,为筛选出的最佳复方,可进一步研制成为治疗腹水病的中草药复方制剂。     

溶藻弧菌脂多糖对石斑鱼免疫功能的影响

脂多糖(Lipopolysaccharide,LPS)是G菌细胞壁中的主要成分之一,是细菌内毒素的主要物质,不仅可引起机体良好的体液免疫应答,而且也可提高机体的非特异性免疫功能。Bog-wald发现LPS能导致实验鱼产生特异性抗体,而且还增强鱼体的免疫吞噬能力;Mac Arthur等报道LPS可提高鲽(pleuronectes platessa)体内巨噬细胞的游走能力;Solem认为LPS可促进大西洋鲑(Atlantic salmon)巨噬细胞的分裂且提高其吞噬活性和鱼体抗感染的能力。本文用溶藻弧菌LPS免疫石斑鱼后,分析了石斑鱼血清抗体效价的变化、LPS对石斑鱼血清溶菌酶、酚氧化酶(PO)和超氧化物歧化酶(SOD)的活性以及抗菌活力等非特异性免疫指标的影响,以及LPS对石斑鱼免疫保护效果,将为充分利用LPS免疫学特性提供理论依据。       

溶藻弧菌转运蛋白TolB的免疫原性与免疫保护性

旨在研究溶藻弧菌(Vibrio alginolyticus)HY9901转运蛋白Tol B作为疫苗候选抗原的可能性,根据已发表的全基因组序列,设计特异性引物PCR扩增tol B的基因全长序列。序列分析显示,该基因(Gen Bank登录号JQ846501)全长1 353 bp,共编码450个氨基酸残基。BLAST分析发现,溶藻弧菌tol B基因与其他已知弧菌的tol B具有较高的同源性,序列保守,可作为共同抗原候选蛋白。用原核表达的tol B蛋白免疫SPF级小鼠,制备多克隆抗体,ELISA效价达1∶40 000。免疫印迹表明鼠抗tol B血清能与诱导后的重组蛋白发生特异反应。为进一步研究tol B对石斑鱼(Epinephelus awoara)的免疫保护性,用Tol B蛋白两次免疫石斑鱼,ELISA检测发现,免疫石斑鱼血清的抗体效价在第4周达到峰值(1∶2 048)。攻毒实验结果表明Tol B对石斑鱼的免疫保护率为76%。结果表明,溶藻弧菌转运蛋白Tol B具有较好的免疫原性和免疫保护性,可作为弧菌亚单位疫苗的候选抗原。     

A型产气荚膜梭菌α毒素基因表达及其免疫保护作用的初步研究

利用PCR技术,从A型产气荚膜梭菌标准株染色体DNA中扩增出α毒素基因,构建了含α毒素基因的重组菌株BL21(DE3)(pXETA02)。经酶切鉴定和序列测定证实,构建的表达质粒pXETA02含有α毒素基因序列。经SDS-PAGE、Western blot分析和ELISA检测,重组菌株表达的α毒素蛋白能够被α毒素单抗识别。表达优化结果表明,以IPTG为诱导剂诱导α毒素表达的优化条件是:培养基pH 7.5,培养温度37℃,IPTG浓度0.8mmol/L,菌体生长密度OD600达到0.8时加入IPTG,诱导时间5h,此时α毒素蛋白表达量为34.83%。以乳糖为诱导剂诱导α毒素表达的优化条件是:培养基pH7.5、培养温度37℃,乳糖浓度0.1g/L,菌体生长密度OD600达到0.8时加入乳糖,诱导时间5h,α毒素蛋白表达量为23.82%。动物实验结果表明,用重组菌株α毒素蛋白免疫的小鼠可以抵抗1MLD的A型产气荚膜梭菌标准株C57-1毒素攻击。     

弧菌外膜蛋白OmpU的免疫交叉反应性和交叉保护性北大核心CSCD

【目的】通过对弧菌外膜蛋白Omp U的克隆、表达以及免疫学特性分析,明确外膜蛋白Omp U是否为弧菌的共同抗原,并具有免疫交叉反应性和交叉保护性。【方法】对弧菌外膜蛋白omp U基因进行克隆和生物信息学分析。分别制备副溶血弧菌、溶藻弧菌、创伤弧菌、拟态弧菌和霍乱弧菌的Omp U重组蛋白抗血清,对Omp U的免疫交叉反应特性以及抗原表位定位情况进行比较分析。以霍乱弧菌的Omp U重组蛋白免疫小鼠后,再以多种弧菌进行攻毒,分析其交叉免疫保护作用。【结果】外膜蛋白Omp U在弧菌种内和种间相似性分别为73.0%–100%和58.6%–89.0%,并至少存在9个保守的B细胞抗原表位。Omp U重组蛋白抗血清在弧菌种内和种间均产生显著的免疫交叉反应,识别弧菌中分子量35–40 k Da的同源蛋白。副溶血弧菌ATCC17802、创伤弧菌ATCC27562和拟态弧菌ATCC33653来源的Omp U重组蛋白抗体能识别供试菌株,提示这些菌株的Omp U抗原表位定位于细胞表面。Omp U重组蛋白对免疫后的小鼠具有交叉免疫保护作用,攻毒实验后小鼠相对存活率(RPS)为43.0%–100%。【结论】上述结果表明,外膜蛋白Omp U是弧菌中一种保守的共同抗原,具有免疫交叉保护性,可以作为弧菌广谱疫苗的候选抗原。     

金黄色葡萄球菌多组分疫苗制备及对小鼠的保护性评价

目的筛选多株金黄色葡萄球菌(Staphylococcus aureus, SA)菌株,为疫苗研发提供备选菌株,并对多组分金黄色葡萄球菌疫苗进行小鼠交叉保护性初步评估。方法通过菌株耐药性、毒力试验筛选获得金黄色葡萄球菌候选菌株;优化菌体破碎和酶解条件获得胞质抗原,并对胞质抗原进行免疫保护性研究以确定最佳免疫剂量;采用抗体中和滴度方法评价类毒素抗原免疫效果;采用多组分疫苗对候选株免疫保护性及同种属其他菌株的交叉保护性进行试验研究。结果 12株金黄色葡萄球菌候选菌株均具有多重耐药性,且对庆大霉素、环丙沙星及苯唑西林的耐药性都比较高,均为83.33%,但都对万古霉素敏感;菌株SA59和SA79毒力分别为34.19 LD_(50)和11.96 LD_(50);菌体破碎最佳条件为3～4次,破碎率达到90%以上,胞质抗原酶解的最佳条件为600 mg胞质抗原在2～4 mg胰蛋白酶条件下,消化至少2 h,抗原含量基本保持不变;SA79胞质抗原免疫剂量不低于1.0 mg/mL时,保护率均70%。类毒素抗原5 EC/mL (A组)、8 EC/mL(B组)和10 EC/mL(C组)免疫小鼠后,血清中抗体中和效价均值分别为2.13、3.13和3.50 AE/mL,B组和C组免疫后的抗体中和效价差异无统计学意义(P_(BC)=0.224,P0.05),但均高于A组,具有统计学意义(P_(AB)=0.008,P_(AC)=0.001,P0.05)。多组分疫苗对候选菌株SA79、SA59的保护率分别为80%和70%,对外毒素的保护率为60%;多组分疫苗对同种属其他菌株的交叉保护率在50%～100%之间,保护率均≥50%。结论多组分金黄色葡萄球菌疫苗对候选株具有保护性,也对同种属其他菌株具有保护性,为后续预防用金黄色葡萄球菌疫苗的工艺开发提供数据支持。     

梅州市两次麻疹疫苗强化免疫效果分析

目的综合评估分析梅州市两次麻疹疫苗强化免疫效果,为消除麻疹提供科学依据。方法综合分析麻疹疫苗强化免疫现场调查资料、评估法定传染病报告系统中麻疹发病率的变化;随机对辖区内1～12岁健康儿童216名,采用酶联免疫吸附试验(ELISA)进行强化免疫前及完成二次强化免疫后麻疹lgG抗体水平监测。结果监测人群完成二次强化免疫后麻疹IgG抗体阳性率达100.00%(216/216),2009年强化组、2010年强化组麻疹IgG抗体保护率和几何平均滴度(GMT)分别为82.08%、87.62%和1958.83、2050.26,均显著高于强化免疫前;2009年强化免疫后麻疹年发病率由强化免疫前五年平均发病率1.71/10万下降至0.22/10万,下降率87.13%,2010年强化后麻疹年发病率再次下降(0.039/10万),下降率82.27%。结论梅州市两次麻疹疫苗强化免疫效果显著,均大幅度降低了麻疹发病率、提高了人群麻疹抗体水平。     

Lipopolysaccharide composition and virulence properties of clinical and environmental strains of Vibrio fluvialis and Vibrio mimicus.

Vibrio mimicus strains W-26768 (stool isolate) and N-1301 (environmental isolate) and Vibrio fluvialis strains AA-18239 (stool isolate) and M-940 (environmental isolate) were studied for virulence properties and lipopolysaccharide composition. All four strains were hydrophobic, produced cytotoxin, adhered to HeLa cells and showed mannose-sensitive agglutination of guinea pig erythrocyte. The strains were negative for enterotoxin production and were mostly susceptible to the common antibiotics. The environmental and clinical isolates of both species were antigenically unrelated to each other. Lipopolysaccharide antigen analysis showed that O-antigen polysaccharides of two strains of V. fluvialis and two strains of V. mimicus differed with respect to the sugar components. Only LPS from V. mimicus W-26768 showed the presence of an unusual sugar, 3,6-dideoxy-3-acetamido-hexose. The sugar compositions of these V. fluvialis and V. mimicus strains differed from those of previously reported Japanese isolates. These differences probably reflect differences in the serogroup of strains.     

Variable gene family usage of protective and non‐protective anti‐Vibrio cholerae O1 LPS antibody heavy chains

Vibrio cholerae causes cholera, an enteric disease of humans that is a worldwide problem. The O1 serogroup of Vibrio cholerae contains two predominant serotypes (Inaba and Ogawa) of LPS, a proven protective antigen for humans and experimental animals. We generated B‐cell hybridomas from mice immunized with either: (i) two doses of purified Inaba LPS; (ii) two doses of an Inaba hexasaccharide conjugate (terminal six perosamine bound to a protein carrier), (iii) four doses of purified Inaba LPS; or (iv) a low dose of purified Inaba LPS followed by a booster with the Inaba conjugate. We showed previously that the first and third immunization protocols induce vibriocidal antibodies, as does the fourth; the second protocol induces antibodies that bind Inaba and Ogawa LPS but are not vibriocidal. Anti‐LPS mAbs derived from hybridomas resulting from each immunization protocol were characterized for binding to Inaba and Ogawa LPS, their vibriocidal or protective capacity, and the variable heavy chain family they expressed. LPS immunogens selected different LPS‐specific B cells expressing six different Vh chain families. Protective and non‐protective mAbs could express variable regions from the same family. One mAb was specific for Inaba LPS, the other mAbs were cross‐reactive with both LPS serotypes. Sequence comparison suggests that the pairing of a specific light chain, somatic mutation, or the specific VDJ recombination can modulate the protective capacity of mAbs that express a common variable heavy chain family member.     

Virulence and molecular typing of Vibrio harveyi strains isolated from cultured dentex,gilthead sea bream and European sea bass

Vibrio harveyi was isolated from internal organs or ulcers of diseased and apparently healthy gilthead sea bream (Sparus aurata) and European sea bass (Dicentrarchus labrax) cultured in several fish farms located on the Spanish Mediterranean coast. The prevalence of the bacterium was significantly higher in European sea bass than in gilthead sea bream, and was closely related to the season in both fish species, occurring almost exclusively on warm months (June to November). After phenotypic characterization, a selection of forty five isolates from gilthead sea bream, sea bass, and several isolates previously obtained from common dentex (Dentex dentex) of the same area, were molecularly typed by automated ribotyping and random amplified polymorphic DNA (RAPD) analysis. Cluster analysis of data established 8 RAPD types and 13 ribotypes among wild isolates, and the combination of both techniques allowed to define fourteen different groups and a clear discrimination of all outbreaks and samplings. Several strains isolated from diseased gilthead sea bream and sea bass and also from asymptomatic sea bream, were tested for virulence in both fish species by intracoelomic injection. All the isolates (11) were pathogenic for sea bass, with nine out of the eleven LD50 values ranging from 1.5 x 10(5) to 1.6 x 10(6) cfu/fish. Gilthead sea bream was unaffected by the seven tested strains, even by those more virulent for sea bass, and only one strain caused a 10% mortality at 4.2 x 10(7) cfu/fish. This is the first report on virulence of V. harveyi for sea bass.     

The ability of two different Vibrio spp. bacteriophages to infect Vibrio harveyi, Vibrio cholerae and Vibrio mimicus

AIMS: To determine the host range of the Vibrio harveyi myovirus-like bacteriophage (VHML) and the cholera toxin conversion bacteriophage (CTX Phi) within a range of Vibrio cholerae and V. mimicus and V. harveyi, V. cholerae and V. mimicus isolates respectively. METHODS AND RESULTS: Three V. harveyi, eight V. cholerae and five V. mimicus isolates were incubated with VHML and CTX Phi. Polymerase chain reaction (PCR) was used to determine the presence of VHML and CTX Phi in infected isolates. We demonstrated that it was possible to infect one isolate of V. cholerae (isolate ACM #2773/ATCC #14035) with VHML. This isolate successfully incorporated VHML into its genome as evident by positive PCR amplification of the sequence coding part of the tail sheath of VHML. Attempts to infect all other V. cholerae and V. mimicus isolates with VHML were unsuccessful. Attempts to infect V. cholerae non-01, V. harveyi and V. mimicus isolates with CTX Phi were unsuccessful. CONCLUSIONS: Bacteriophage infection is limited by bacteriophage-exclusion systems operating within bacterial strains and these systems appear to be highly selective. One system may allow the co-existence of one bacteriophage while excluding another. VHML appears to have a narrow host range which may be related to a common receptor protein in such strains. The lack of the vibrio pathogenicity island bacteriophage (VPI Phi) in the isolates used in this study may explain why infections with CTX Phi were unsuccessful. SIGNIFICANCE AND IMPACT OF THE STUDY: The current study has demonstrated that Vibrio spp. bacteriophages may infect other Vibrio spp.     

Catecholamine-induced stimulation of growth in Vibrio species

AIMS: To evaluate the effect of norepinephrine (NE) and related compounds on the growth of bacteria, we have examined the effect of the neuroendocrine hormone NE and related compounds on the growth of Vibrio parahaemolyticus and other human-pathogenic Vibrio species (Vibrio cholerae, Vibrio vulnificus, and Vibrio mimicus). METHODS AND RESULTS: The effects on bacterial growth were examined using the serum-based medium and viable cells were counted using agar plates. We have shown that NE and its related compounds stimulate growth of V. parahaemolyticus in serum-based medium. This NE-induced growth stimulation was dependent upon the presence of transferrin. NE also stimulated growth of V. mimicus, but not V. cholerae and V. vulnificus. CONCLUSIONS: These results suggest that the Vibrio species differ in their ability to respond to NE. SIGNIFICANCE AND IMPACT OF THE STUDY: It is possible that NE and related compounds modulate the pathogenicity of V. parahaemolyticus and V. mimicus.     

鱼类三种致病菌的粗脂多糖对异育银鲫的免疫原性

用温酚法从柱状嗜纤维菌、嗜水气单胞菌和鳗弧菌中提取的粗脂多糖（LPS）作为免疫原,分别接种异育银鲫后,通过测定受免鱼的交叉凝集抗体效价,头肾和血液中吞噬细胞的吞噬活性和用A.hydrophila活菌攻毒的方法,探讨鱼类3种致病菌的粗LPS对异育银鲫免疫原性的试验结果,结果表明,从3种致病菌中提取的粗LPS对异育银鲫均具有较强的免疫原性,受免鱼的血清中存在对3种致病菌的交叉凝集抗体;与对照鱼相比,头肾和血液中吞噬细胞的吞噬活性明显上升,受免鱼的A.hydrophila活菌攻毒均产生了较强的免疫保护力,说明在每种供试菌的粗LPS上都不同程度地存在3种致病菌的共同保护性抗原。     

Effect of oral immunization with Aeromonas hydrophila ghosts on protection against experimental fish infection

Aims:  To investigate whether oral immunization with Aeromonas hydrophila ghosts (AHG) vaccine can elicit mucosal and systemic immune responses of Carp ( Carassius auratus gibelio ) compared to conventional formalin-killed bacteria (FKC).
Methods and Results:  Fish were fed diets coated with AHG, FKC or phosphate buffered saline (PBS) alone, after immunization, more antigen-specific antibody was significantly detected in serum and intestinal mucus in AHG group than FKC group and PBS group. In addition, after challenged with the parent strain J-1, the survival of bacterial ghost-vaccinated fish was higher than PBS group and FKC group, the relative per cent survival (RPS) being 76·8%, 58·9%, respectively.
Conclusions:  Oral immunization with A. hydrophila ghosts can elicit systemic and mucosal adaptive immune responses and has higher potential to induce protective adaptive immunity than normal vaccine.
Significance and Impact of the Study:  Oral immunization with bacterial ghosts is a promising new solution with potential application to prevent diseases in fish.     

Pathogenicity of Vibrio alginolyticus for Cultured Gilt-Head Sea Bream (Sparus aurata L.)

The in vivo and in vitro pathogenic activities of whole cells and extracellular products of Vibrio alginolyticus for cultured gilt-head sea bream were evaluated. The 50% lethal doses ranged from 5.4 × 10⁴ to 1.0 × 10⁶ CFU/g of body weight. The strains examined had the ability to adhere to skin, gill, and intestinal mucus of sea bream and to cultured cells of a chinook salmon embryo cell line. In addition, the in vitro ability of V. alginolyticus to adhere to mucus and skin cells of sea bream was demonstrated by scanning electron microscopy. The biological activities of extracellular products of V. alginolyticus were hydrolytic activities; the products were able to degrade sea bream mucus. V. alginolyticus was cytotoxic for fish cell lines and lethal for sea bream. Moreover, the extracellular products could degrade sea bream tissues. However, experiments performed with the bath immersion inoculation technique demonstrated that V. alginolyticus should be considered a pathogen for sea bream only when the mucus layer is removed and the skin is damaged.     

High Prevalence of Vibrio cholerae Non-O1 Carrying Heat-Stable-Enterotoxin-Encoding Genes among Vibrio Isolates from a Temperate-Climate River Basin of Central Italy

Vibrio spp. of clinical interest from the Arno River basin (Tuscany, Italy) were investigated in this study. Vibrios were isolated from 70% of water samples. Vibrio cholerae non-O1 was the most prevalent species (82% of isolates), followed by Vibrio mimicus (10%) and Vibrio metschnikovii (8%). Recovery of vibrios was correlated with temperature, pH, and various indicators of municipal pollution. None of the 150 Vibrio isolates carried ctx-related genomic sequences, whereas 18 (14.6%) of the 123 V. cholerae non-O1 isolates and 1 (6.7%) of the 15 V. mimicus isolates carried sto alleles. These findings indicate that considerable circulation of sto-positive vibrios may occur in temperate-climate freshwater environments.