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猪链球菌2型溶血素基因缺失菌株的构建及生物学特性的研究 总被引:1,自引:1,他引:1
溶血素(SLY)在猪链球菌2型(SS2)侵入和裂解细胞的过程中发挥重要作用,被认为是SS2的一种重要的毒力相关因子。为了探讨SLY在2005年中国四川资阳分离强毒株SS205ZY致病过程中的作用,作者利用同源重组基因敲除法成功构建了SS205ZY的sly基因敲除突变菌株(Δsly)。并比较了菌株的溶血能力以及对小鼠的致病力。结果表明sly基因敲除后可导致猪链球菌裂解红细胞的能力显著下降,对小鼠的致病力也有一定程度的减弱,但仍表现较高的致病力。本研究结果提示SLY是猪链球菌裂解细胞的重要毒力相关因子,但造成SS205ZY的高致病性很显然与多种毒力相关因子的协同作用有关。 相似文献
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为了探讨猪链球菌2型(Streptococcus suis serotype 2,SS2)的Ⅲ型溶血素是否具有溶血活性以及Ⅲ型溶血素在SS2致病过程中的作用,本研究利用同源重组基因敲除法成功构建了SS205ZY的Ⅲ型溶血素(slyrp)基因缺失突变菌株△slyrp及双基因缺失突变菌株△sly/△slyrp,并比较了野生菌株和基因缺失突变菌株的溶血能力以及对小鼠的致病力.结果表明,slyrp基因敲除后可导致SS2裂解红细胞的能力有所下降,而双基因缺失突变菌株△sly/△slyrp的溶血能力完全丧失;slyrp基因敲除后对小鼠的致病力没有影响.结果提示猪链球菌2型Ⅲ型溶血素具有一定的溶血能力,该Ⅲ型溶血素在SS2感染过程中,对溶血素(sly)起协同作用,不是SS2主要的毒力相关基因. 相似文献
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根据猪链球菌2型(SS2)HA9801株溶血素(suilysin,SLY)基因全长序列设计引物,扩增SLY基因,与原核表达载体pET-28a连接,转入大肠杆菌Transetta (DE3)中诱导表达,收集表达菌体,超声破壁、镍柱纯化获得可溶性rSLY蛋白,电泳鉴定后测定rSLY的溶血活性及其溶血谱,系统研究温度、酸碱度、离子强度等理化因素对rSLY溶血活性的影响.结果表明,本试验建立的rSLY原核表达体系能高效可溶性表达具有溶血活性的rSLY,纯度达电泳纯,相对分子质量为54 000左右,100 mL菌液诱导后能纯化出约8 mg电泳纯的rSLY.rSLY具有高溶血活性,溶血比活为4 057 HU/mg.rSLY对多种动物的红细胞有溶血作用,其中对猪、兔和豚鼠的作用最强.rSLY在4℃保存时溶血活性最稳定,保存48h后溶血活性不降低.在pH 6~7和离子强度为500 mmol/L时溶血活性最高.本试验获得了高表达、可溶性、高溶血活性的rSLY,首次系统研究了不同理化因素对rSLY生物学活性的影响,为SLY致病机理深入研究及SS2亚单位疫苗和诊断试剂的研制奠定了基础. 相似文献
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《中国动物传染病学报》2018,(6)
为探讨河南省2型猪链球菌的毒力及分布情况,本实验设计3对引物,分别扩增溶菌酶释放蛋白(muramidase-released protein,MRP)、胞外因子(extracellular protein fateror,EPF)和溶血素(suilysin,SLY)基因,对2016年1月~2016年12月从河南省猪场采集的各种组织病料中分离鉴定出的87株2型猪链球菌进行了初步的小鼠毒力试验和mrp、epf、sly基因的扩增。结果表明,河南省流行的2型猪链球菌的菌株均对小鼠有毒力,共有8种毒力基因型,其中以毒力相对高的sly+mrp+epf+型为主,其次为sly+mrp-epf+型和sly-mrp+epf+型。 相似文献
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为了治疗和控制猪链球菌病,本文通过最小抑菌浓度、生长曲线的测定以及溶血试验等筛选针对猪链球菌溶血素(Suilysin,SLY)的抑制剂,研究发现较低浓度的黄芩提取物对猪链球菌几乎没有抗菌活性,但可以显著抑制猪链球菌SLY所诱导的溶血活性;并且黄芩提取物可以显著降低猪链球菌感染所引发的细胞损伤;此外,体内研究发现,黄芩提取物可降低猪链球菌感染小鼠的死亡率。综上,本研究结果表明,黄芩提取物可以通过抑制SLY的生物活性而在猪链球菌感染中发挥治疗作用,是一种具有开发价值、治疗猪链球菌感染的先导复合物。 相似文献
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PCR扩增溶血素(suilysin, SLY)基因,克隆后测序,利用原核表达载体pET-28a及表达宿主菌E.coli BL21(DE3)构建SLY原核表达系统,采用SDS-PAGE检测蛋白表达情况,借助Ni-NTA亲和层析法纯化蛋白,获得具有序列保守且可溶性的SLY蛋白。显微镜形态学观察显示,质量浓度为0.4 mg/L的SLY在37℃条件下作用2 h可使贴壁hCMEC/D3(人脑微血管内皮细胞)全部死亡。通过分光光度法测定SLY对人红细胞的溶血活性,结果显示1μg SLY可使2.25×1010个人红细胞完全溶解。Real-time RT-PCR结果显示,SLY处理所致破碎的红细胞上清可使hCMEC/D3细胞炎性因子IL-6和IL-8转录水平分别升高80倍和100倍以上,且该作用效果显著高于超声破碎红细胞的方式。结果表明,SLY具有显著的细胞毒性,其导致红细胞溶血可能是猪链球菌2型(Streptococcus suis type 2,SS2)引起机体炎症反应的原动力。 相似文献
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猪链球菌在世界范围内广泛存在,是危害养猪业发展的重要传染源之一,能够引起猪脑膜炎、关节炎、肺炎、心内膜炎、流产以及仔猪的突然死亡。溶血素(SLY)是猪链球菌分泌的唯一能够引起细胞毒性的可溶性蛋白,它能在宿主细胞膜上打孔引起细胞崩解。然而,不是所有的猪链球菌致病株均分泌SLY蛋白。 相似文献
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目的预测猪链球菌2型(SS2)溶血素(SLY)B细胞表位。方法以DNAstar分析为主,综合分析二级结构、亲水性、表面可及性及抗原性指数,辅以吴玉章氨基酸抗原指数计算方法进行SS2溶血素B细胞表位预测。结果推测最有可能的B细胞表位位于溶血素N端第74~85、231~244区域位。结论应用多参数预测SS2溶血素的特征,为表位疫苗的研制奠定了基础。 相似文献
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魏静 《四川畜牧兽医学院学报》2009,(4):28-32
在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。 相似文献
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本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。 相似文献
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REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air. 相似文献
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Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF
Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo. 相似文献
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乳酸杆菌作为益生菌广泛用于人和动物.本文综述了乳酸杆菌改善宿主健康的机制.乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道.文章重点讨论了乳酸杆菌表面成分(表面蛋白、脂磷壁酸和肽聚糖)与肠道受体(C型凝集素受体、Toll样受体和Nod样受体),阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制. 相似文献