大肠埃希菌不耐热肠毒素研究进展

大肠埃希菌不耐热肠毒素(LT)是产毒性大肠埃希菌产生的一种能导致人畜腹泻的毒素,由六聚体蛋白形成AB5型结构.A亚基具有ADP核糖基转移酶活性,而B亚基为五聚体,主要与表达于真核细胞表面的神经节苷脂GM1结合.LT具有很强的免疫原性和黏膜免疫佐剂活性.为了将其毒性与佐剂活性分开,研究者构建了一系列无毒或减毒的突变体.证明突变体具有佐剂活性,并发现没有毒性的AB复合物以及酶活性在佐剂活性中发挥的作用是分开的.野生型LT、LT突变体以及B亚基与外源抗原共同免疫机体后,对机体免疫系统具有调节作用.     

大肠埃希菌热敏性肠毒素B亚基研究进展

产肠毒素大肠埃希菌(EnterotoxigenicE.coil,ETEC)是引起幼畜、婴幼儿及旅游者腹泻的重要病原之一。ETEC产生两类肠毒素,一种是对热敏感的热敏性肠毒素(heat-labile enterotoxin,LT),另一种是对热不敏感的耐热性肠毒素(heat-stable enterotoxin,ST)。LT不仅是ETEC主要的毒力因子,而且还是一种重要的黏膜佐剂,它由A、B亚基组成,由于LT A具有毒性作用,限制了LT作为黏膜免疫佐剂的应用;而LT B无毒且具有黏膜佐剂活性,使其成为备受关注的佐剂之一。近年来对LT B的结构、介导的免疫调节分子机制、突变体及其佐剂作用已进行了较为深入的研究,为充分利用LT B的黏膜免疫佐剂功能奠定了基础。     

生鲜牛乳中产肠毒素大肠埃希菌环介导等温扩增技术的建立与应用

为了快速检测生鲜牛乳中的产肠毒素大肠埃希菌(enterotoxigenic E.coli,ETEC),防止食源性产肠毒素大肠埃希菌给人类造成的危害,建立快速检测不耐热型产肠毒素大肠埃希菌的环介导等温扩增方法(LAMP)。敏感性和特异性试验结果表明,该方法敏感性高,特异性强,能够从生鲜牛乳中检测到1pg产肠毒素大肠埃希菌DNA,与其他型大肠埃希菌及细菌不发生交叉反应。利用建立的LAMP技术对来自西宁市奶牛场及自由市场的21份生鲜牛乳样品进行检测,6份样品呈阳性,阳性检出率为28.6%,从分子水平为生鲜牛乳中产肠毒素大肠埃希菌的检测提供了一种快速、准确的手段,对保障生鲜牛乳的食品安全有重要意义。     

产肠毒素性大肠杆菌肠毒素的研究概况

本文分析了大肠杆菌耐热肠毒素 (heat-stable,ST)和不耐热肠毒素 (heat- labile,LT)生物学特性、分子水平机制及其应用价值。一方面着重讲述 LT作为粘膜免疫佐剂的研究前景 ,利用体外定点突变方法构建不同的突变株并且均具有不同程度的佐剂活性 ,是霍乱毒素 (Choleratoxin,CT)很有希望的替代品。另一方面讲述ETEC基因工程亚单位疫苗的研究概况。ETEC只有 LT、ST两类肠毒素 ,通过不同方式构建融合基因探讨对 ETEC性腹泻防治效果。目前 ,这两方面均卓有成效 ,但还有许多的难点需进一步的研究     

大肠杆菌不耐热肠毒素突变体作为佐剂的研究进展

黏膜免疫是防止病原菌侵入黏膜表面引起疾病的最有效的途径,通过黏膜免疫不仅能产生全身免疫反应,还能产生局部的黏膜免疫反应,该免疫途径无痛苦且易操作,同时减少疾病传播的风险.但大多数抗原的黏膜免疫原性都很差,通过口服或滴鼻免疫可溶性蛋白通常引起特异性免疫耐受,这些使得在黏膜免疫中使用恰当的佐剂成为必须. 不耐热肠毒素（Heat— labile enterotoxin,LT）是由肠毒素大肠杆菌（enterotoxigenic Escherichia col i,ETEC）分泌的一种外毒素,既有较强的免疫原性又有较强的黏膜佐剂效应.但由于强的毒性,限制了它的广泛应用,因此通过构建各种突变体使之具备优良的佐剂活性且没有显著的毒性是当前研究的主要目标.本文主要从突变体的酶活性、毒性以及佐剂活性进行综述,为黏膜疫苗的研制打下一定基础.     

猪大肠杆菌不耐热肠毒素基因的PCR检测

以产肠毒素性大肠埃希氏菌(ETEC)不耐热肠毒素(LT)保守序列为靶序列,设计合成了一对可扩增336 bp目的片段的引物,建立了检测ETEC不耐热肠毒素(LT)基因的PCR方法.该方法对987p 、鼠伤寒沙门氏杆菌、猪肺疫巴氏杆菌和链球菌的检测结果均为阴性.对15株分离自腹泻仔猪的待检菌株进行检测,有3株LT基因阳性.结果表明:该方法的特异性和敏感性较高,可用于ETEC的临床快速诊断和流行病学调查.     

大肠杆菌不耐热肠毒素的分子生物学及粘膜免疫佐剂效应

大肠杆菌不耐热肠毒素(Heat-Labile,LT)是由产肠毒素大肠杆菌(enterotoxigenicEscherichiacoli,ETEC)分泌的一种外毒素。LT既有较强的免疫原性又有较强的粘膜佐剂效应,其毒力较霍乱毒素(choleratoxin,CT)小而被认为是替代CT的最有潜力的粘膜免疫佐剂。本文从LT的分子结构、分子生物学特性、免疫原性、粘膜佐剂效应及其作用机制以及LT的粘膜免疫佐剂的应用等方面进行了讨论。     

产肠毒素性大肠埃希菌主要毒力因子及疫苗的研究进展

产肠毒素性大肠埃希菌是目前幼畜腹泻的主要致病因素.文章综述了在畜牧业中产肠毒素性大肠埃希菌的主要致病因子黏附素和肠毒素、EatA及其生化特性,并介绍了产肠毒素性大肠埃希菌的传统灭活苗及新型基因工程疫苗的研究进展.     

大肠埃希菌强毒力岛致病机制研究进展

大肠埃希菌(Escherichia coli)常引起婴儿和幼畜(禽)严重腹泻和败血症.近年来对于大肠埃希菌强毒力岛(HPI)致病机制的研究已有大量文献记载,但大肠埃希菌具体的致病机制目前尚不明确.研究表明耶尔森菌强毒力岛与一些肠道致病菌的致病性密切相关,如大肠埃希菌、沙门菌、克雷伯菌等.引起大肠埃希菌致病的因素多种多样,如气候变化,应激,机体本身状况等.论文就大肠埃希菌HPI的结构基因及其分子致病机制的研究现状进行综述.     

双重PCR检测猪产肠毒素性大肠埃希菌耐热肠毒素基因

为了研究猪产肠毒素性大肠埃希菌(ETEC)耐热肠毒素基因(STa、STb)的临床快速诊断方法,试验以已发表的猪ETEC耐热肠毒素基因保守区为目的片段设计合成了2对可扩增182bp和108bp的引物,建立了检测ETEC耐热肠毒素基因的双重PCR检测方法。结果表明:该方法对猪肠出血性大肠埃希菌(EHEC)EDL933、猪链球菌、鼠伤寒沙门杆菌和猪肺疫巴氏杆菌的检测结果均为阴性;对11株分离自广东佛山地区腹泻仔猪的待检菌株进行检测,结果STa+5株、STb+2株,其中STa+STb+1株。     

维生素A的免疫研究进展

维生素A是一种动物所必需的营养素和重要抗氧化剂,具有保护上皮组织完整性、促进骨骼发育、调节新陈代谢和胚胎发育、增强机体免疫力等功能。随着研究的深入,人们逐渐发现维生素A在肠黏膜免疫和诱导淋巴细胞的凋亡中也充当着重要的免疫佐剂。为进一步拓宽营养与免疫研究视野,作者就维生素A在免疫方面的最新研究进展进行综述。     

大肠杆菌热敏毒素研究概况

本文在分析大肠杆菌热敏毒素（LT）生物学特性及其分子学水平研究的基础上，从蛋白质和基因水平阐述了猪源LT与人源LT的亲缘关系，评述了LT在研制人畜大肠杆菌腹泻疫苗中的应用价值，也通过对与LT具有相似蛋白和基因结构的霍乱毒素CT的分析，表明二者具有相同的进化起源，认为通过定点诱变的LT能够取代CT用作幽门螺杆菌疫苗的粘膜免疫佐剂。     

重组细胞因子在禽类疫苗中的应用进展

细胞因子是免疫系统的重要调节因子,具有明显的免疫佐剂效应。随着鸡细胞因子(IL-2,IL-6,IL-12,IL-18,IFN-γ等)相继克隆成功,重组细胞因子在禽类疫苗中的应用研究也逐步深入。研究表明,用原核、真核载体或者病毒构建的细胞因子重组质粒或表达的重组蛋白,能很好的发挥免疫佐剂的活性。论文综述了细胞因子的免疫增强机制,以及重组细胞因子在现代禽类疫苗中的应用概况。     

Systemic adjuvant effect of cholera toxin in the chicken.

Cholera toxin (CT) is a well-known mucosal adjuvant in mammals, but it does not give conclusive results in chickens. Cells from the chicken immune system may be insensitive to CT activity. Our results showed that intravenously administered CT had strong immunomodulatory effects on chicken antigen-specific T- and B-cell immune responses. Seven and eight days post-inoculation (p.i.), chickens immunized with KLH and CT exhibited a faster and higher specific proliferative response in the spleen after in vitro restimulation than chickens immunized with KLH alone. At the same time, the specific antibody response in serum was significantly higher, with a strong IgG enhancement and a peak of IgA in chickens immunized with KLH and CT. The anti-KLH splenic antibody response in vitro involved a significant increase in specific IgG and IgA isotypes when CT was used as adjuvant. In conclusion, as in mammals, systemic CT demonstrated strong adjuvant properties in chickens enhancing T-cell priming in vivo and, thus, leading to increased specific antibody production, including IgA.     

Administration of poly[di(sodium carboxylatoethylphenoxy)]phosphazene (PCEP) as adjuvant activated mixed Th1/Th2 immune responses in pigs

The selection of an optimal adjuvant to enhance the potency and longevity of antigen specific immune responses has always been imperative for the development of more effective and safer vaccines. A balanced type of immune enhancing ability of a new adjuvant known as polyphosphazene (PCEP) has been demonstrated in mice. In the present study we have compared the humoral and cellular immune responses to vaccine formulations containing Actinobacillus pleuropneumoniae outer membrane antigen (OmlA) with PCEP or Emulsigen as adjuvants. Our data showed a significant improvement and a shift toward more balanced immune responses when OmlA antigen was formulated with PCEP and CpG ODN. Moreover, in contrast to Emulsigen, immunization with PCEP did not result in local injection site reactions highlighting its potential as a safe and effective adjuvant for pigs. Further, the ease of formulation, administration and relatively low per dose cost of PCEP make it a promising adjuvant for pigs.     

猪繁殖与呼吸综合征免疫防制新途径的研究进展

猪繁殖与呼吸综合征(porcine reproductive and respiratory syndrome,PRRS)是一种主要表现为母猪繁殖障碍与仔猪呼吸道症状的传染病。近年来,猪繁殖与呼吸综合征病毒(porcine reproductive and respiratory syndrome virus,PRRSV)变异株不断出现,免疫逃避及持续性感染使得猪群发病率或复发率均相继增高,给养猪业带来了巨大的损失。目前所采用的胃肠道途径接种活疫苗或灭活疫苗的方法无法诱导对猪群的全面保护作用。为减少养猪业的经济损失,亟需研制新防制方法和新疫苗接种途径。作者主要从黏膜免疫的免疫部位、呼吸道保护性黏膜免疫反应诱导、黏膜免疫途径、佐剂的选择及病毒的免疫抑制反应等方面简要论述了有效防制PRRSV的黏膜免疫方法的研究进展,为进一步了解黏膜免疫抵御PRRSV突变株感染及黏膜疫苗研制等方面提供有用的信息。     

Development of a water-in-oil-in-water adjuvant for foot-and-mouth disease vaccine based on ginseng stem-leaf saponins as an immune booster

There has been an increasing interest in finding new formulations that qualify as vaccine adjuvants, which must be safe, stable, and have the capacity to stimulate a strong immune response. In this study, a basic formulation of a water-in-oil-in-water (W/O/W) adjuvant CV13 was developed, and ginseng stem-leaf saponins (GSLS) were added as an immune booster into oil phase. The physicochemical properties of the adjuvant were tested. Furthermore, the immune activity and the adjuvant effects, as indicated by the foot-and-mouth disease virus (FMDV) antigen were evaluated. The results showed that CV13 was similar in appearance to ISA 206 and could package FMDV antigen into a stable W/O/W emulsion. The FMD vaccine prepared with CV13 alone or CV13 containing GSLS achieved pharmaceutical characteristics comparable to a vaccine prepared with ISA 206, moreover the structural stability of the CV 13 vaccine was found to be better. Mice that were immunized with the FMD vaccine prepared with CV13 containing GSLS presented a significantly higher LPBE antibody titer and splenocyte proliferation rate than those immunized with a vaccine prepared with CV13 alone (p < 0.05). In addition, there was no significant difference between the groups that were immunized with FMD vaccine prepared with CV13 containing GSLS and ISA206 in terms of cellular and humoral immune response. In this paper, CV13 containing GSLS shows excellent immunologic adjuvant effect in mice model, and this new adjuvant may provide a potential choice for FMD vaccine production in the future.     

The extradomain a of fibronectin enhances the efficacy of lipopolysaccharide defective Salmonella bacterins as vaccines in mice

ABSTRACT: The Extradomain A from fibronectin (EDA) has an immunomodulatory role as fusion protein with viral and tumor antigens, but its effect when administered with bacteria has not been assessed. Here, we investigated the adjuvant effect of EDA in mice immunizations against Salmonella enterica subspecies enterica serovar Enteritidis (Salmonella Enteritidis). Since lipopolysaccharide (LPS) is a major virulence factor and the LPS O-polysaccharide (O-PS) is the immunodominant antigen in serological diagnostic tests, Salmonella mutants lacking O-PS (rough mutants) represent an interesting approach for developing new vaccines and diagnostic tests to differentiate infected and vaccinated animals (DIVA tests). Here, antigenic preparations (hot-saline extracts and formalin-inactivated bacterins) from two Salmonella Enteritidis rough mutants, carrying either intact (SEΔwaaL) or deep-defective (SEΔgal) LPS-Core, were used in combination with EDA. Biotinylated bacterins, in particular SEΔwaaL bacterin, decorated with EDAvidin (EDA and streptavidin fusion protein) improved the protection conferred by hot-saline or bacterins alone and prevented significantly the virulent infection at least to the levels of live attenuated rough mutants. These findings demonstrate the adjuvant effect of EDAvidin when administered with biotinylated bacterins from Salmonella Enteritidis lacking O-PS and the usefulness of BEDA-SEΔwaaL as non-live vaccine in the mouse model.