甘露糖结合凝集素相关的丝氨酸蛋白酶2研究进展

甘露糖结合凝集素相关的丝氨酸蛋白酶(mannan binding lectin-associated serine protease,MASP)和甘露糖结合凝集素(mannan binding lectin,MBL)是补体激活的凝集素途径中的关键因子,发挥着至关重要的作用。MBL或纤维胶凝蛋白(ficolin)分子通过C端糖识别域(carbohydrate recognition domain,CRD)与病原微生物表面的糖类结构结合,其胶原样区(collagen-like region,CLR)与MASP结合,使无活性的MASP转换为活性MASP,从而激活补体凝集素途径。     

鸡甘露糖结合凝集素研究进展

鸡甘露糖结合凝集素是天然免疫防御系统中一种重要的免疫因子,具有识别病原微生物、介导调理吞噬、激活补体等功能。研究发现,鸡体内甘露糖结合凝集素的水平变化与疾病的易感性相关,表明甘露糖结合凝集素在抗病育种方面具有重要的研究价值。本文对鸡甘露糖结合凝集素的分子结构、功能、遗传特性及其与疾病的相关性进行了系统的分析和阐述。     

甘露糖结合凝集素基因的研究进展

疾病是影响畜牧业生产的主要因素，虽然传统的疾病控制方法对疾病的预防和治疗起到了重要作用，但随着分子生物学和基因工程技术的发展，分析在抗性和易感群体中候选基因的标记等位基因频率差异，结合遗传育种技术，提高家畜的抗病性与健康水平已成为当今提高家畜生产水平的重要途径。甘露糖结合凝集素（mannan-binding lectins，MBL）是构成人和动物血清补体凝集素途径的主要成分，在先天免疫过程中起重要作用。笔者简述了MBL的分布、结构、功能，介绍了MBL基因与抗病力的关系，对其作为家畜抗病育种遗传标记的应用前景进行了展望。期望MBL作为遗传标记，通过标记辅助选择进行抗病育种可以培育出抗病力强的家畜品种。     

补体C3基因多态性与相关疾病研究进展

在补体各成分中,补体第三组分(C3)在血清中含量最高,是补体系统的核心.C3在功能上不仅处于补体经典途径、甘露糖结合凝集素途径和补体旁路途径三条激活途径的汇合点,还是C3b依赖的阳性反馈环路的基础;而且C3裂解片段及其结合蛋白复杂多样,在免疫防御、免疫调控以及免疫病理中发挥着重要的作用.当C3基因发生突变或缺失时会造成C3缺陷性疾病,常伴发免疫性疾病及反复细菌感染,患者对病原菌感染的易感性显著增加.论文概述了C3基因结构及其多态性以及其与机体易感性的关联性.     

鸡甘露糖结合凝集素的研究进展

甘露糖结合凝集素（mannan-binding lectin，MBL）又称甘露糖结合蛋白（mannam-bindng protein．MBP），是一种广泛存在于人和动物体内的胶凝素（collagen）．属C型凝集素（Ca2＋依赖型）超家族。MBL由肝细胞产生并分泌至血液中．能特异性地与多种细菌、病毒、真菌以及恶性细胞表面具有的甘露糖、N-乙酰甘露糖胺、N-乙酰葡糖胺糖类结构结合。     

胶原凝集素参与免疫反应的研究进展

胶原凝集素为C-型凝集素,主要包括甘露糖结合凝集素(mannan-binding lectin,MBL)、表面活性物质蛋白(SP)-A和-D等。MBL可以促进或抑制炎症反应的发生;SP-A和SP-D可与多种微生物和致敏原互作,产生调理性作用,使微生物生长被抑制、外源性抗原失效,在免疫反应在发挥重要作用。     

不同MBL基因型绵羊感染绵羊肺炎支原体后的免疫相关因子表达规律分析

将32只2月龄中国美利奴羊人工感染绵羊肺炎支原体(MP),分别在攻毒前1 d(-1 d)、攻毒后1 d、7 d、14 d和21 d收集新鲜抗凝血,提取总RNA后应用Real-time PCR的方法定量检测细胞因子IL-2、IL-4、IFN-γ、TNF-α,补体C1、C3和甘露糖结合凝集素(MBL)。结果表明,不同MBL基因型绵羊攻毒感染后血清MBL浓度呈下降趋势,其中MBL浓度较高的C型和D型绵羊,其促炎因子IL-2、IFN-γ浓度较高,抗炎因子IL-4在攻毒后1d呈升高趋势,此后开始下降;MBL浓度较低的A型和B型绵羊,攻毒后其TNF-α浓度升高显著,随炎症的舒缓,逐渐降低;补体C1和C3在攻毒后表现出不同的变化,证实MP感染后,激活补体途径,可能与MBL的浓度变化有关。     

血清中不同甘露(聚)糖结合凝集素浓度的绵羊感染绵羊肺炎支原体后免疫因子表达的变化

为研究中国美利奴羊不同甘露(聚)糖结合凝集素(MBL)浓度感染绵羊肺炎支原体(MO)的免疫因子水平变化,本研究选择血清中MBL高、低浓度的绵羊各6只(感染组和对照组各3只),感染组人工感染MO,分别在人工感染前和感染后不同时间,采用荧光定量PCR法检测血液中血清因子及补体表达水平。结果显示,不同MBL浓度的绵羊人工感染后MBL m RNA水平呈下降趋势,MBL高浓度促炎因子IL-2和IFN-γ的m RNA表达水平较高,抗炎因子IL-4的m RNA表达水平在感染后1 d升高,此后开始下降,而IL-4的m RNA水平在14 d后有所升高;MBL低浓度羊感染后其TNF-α的m RNA水平显著升高,随炎症的缓解,逐渐降低;补体C1和C3的m RNA在感染后表现出不同的变化,MO感染可以激活补体途径。本研究结果表明,低血清MBL浓度与绵羊支原体肺炎具有一定的相关性,MBL不同浓度组之间其IL-2、IL-4、TNF-α、IFN-γ、补体C1、C3水平存在差异,低浓度MBL的绵羊更易发生比较严重的炎症反应。     

绵羊甘露糖结合凝集素基因启动子区甲基化与绵羊支原体肺炎相关性研究

甘露糖结合凝集素(MBL)是一种由肝脏合成和分泌的急性期蛋白,属于胶原凝集素家族,通过激活补体和调理吞噬作用在抗感染的起始阶段起主导作用。为研究绵羊MBL基因启动子区甲基化与绵羊支原体肺炎感染的相关性,本研究利用绵羊肺炎支原体(M.ovipneumonia)标准株Y-98气管内接种3月龄绵羊,对照组接种相同体积的灭菌生理盐水,利用BSP甲基化检测技术对感染组及对照组绵羊中MBL基因启动子区甲基化及血清中MBL浓度水平进行检测。结果显示,MBL基因启动子区甲基化CpG数量和甲基化发生的位点均与血清中MBL水平有关,而且MBL基因启动子区每个CpG的甲基化对于MBL水平的影响均存在差异。本研究为进一步诊断与治疗绵羊支原体性肺炎提供重要的实验依据。     

凝集素在甲壳类动物免疫学方面的研究进展

凝集素属于一种糖蛋白或结合糖的模式识别分子蛋白,存在于植物、动物、微生物中,按物种来源可分为植物凝集素、动物凝集素、原生生物凝集素、细菌凝集素和病毒凝集素。甲壳类动物凝集素可以同时参与多项免疫反应,在维持甲壳类动物机体稳态、免疫防御以及免疫监视中发挥重要作用。本文基于凝集素的定义、分类及功能,介绍了甲壳类动物凝集素的两种主要类型——C型凝集素（C-type lectins,CTLs）和纤维蛋白原样结构域免疫凝集素（fibrinogen-like domain immunolectins,FBGLs）,旨在提升对甲壳类动物先天性免疫的认识水平,为甲壳类动物疾病防治提供新的思路和方法。     

Characterization of a mannose-binding lectin from channel catfish (Ictalurus punctatus)

Mannose-binding lectin (MBL) is an important component of innate immunity capable of activating the lectin pathway of the complement system. A MBL gene was isolated from channel catfish (Ictalurus punctatus). The deduced protein contains a canonical collagen-like domain, a carbohydrate recognition domain (CRD), and a neck region similar to mammalian mannose-binding lectin. The catfish mannose-binding lectin CRD contains the EPN motif shown previously to mediate mannose specificity. The catfish mannose-binding lectin showed 30-43% identity with MBL protein sequences of rainbow trout, zebrafish, common carp, and goldfish, and 33-35% identity with sequences of mammalian species. In this study, while liver was the predominant source of mannose-binding lectin gene expression in healthy tissues, mannose-binding lectin expression in spleen rose sharply following challenge with a Gram-negative bacterium.     

Comparative genetics and innate immune functions of collagenous lectins in animals

Collagenous lectins such as mannan-binding lectins (MBLs), ficolins (FCNs), surfactant proteins A and D (SP-A, SP-D), conglutinin (CG), and related ruminant lectins are multimeric proteins with carbohydrate-binding domains aligned in a manner that facilitates binding to microbial surface polysaccharides. MBLs and FCNs are structurally related to C1q, but activate the lectin complement pathway via interaction with MBL-associated serine proteases (MASPs). MBLs, FCNs, and other collagenous lectins also bind to some host macromolecules and contribute to their removal. While there is evidence that some lectins and the lectin complement pathway are conserved in vertebrates, many differences in collagenous lectins have been observed among humans, rodents, and other vertebrates. For example, humans have only one MBL but three FCNs, whereas most other species express two FCNs and two MBLs. Bovidae express CG and other SP-D-related collectins that are not found in monogastric species. Some dysfunctions of human MBL are due to single nucleotide polymorphisms (SNPs) that affect its expression or structure and thereby increase susceptibility to some infections. Collagenous lectins have well-established roles in innate immunity to various microorganisms, so it is possible that some lectin genotypes or induced phenotypes influence resistance to some infectious or inflammatory diseases in animals.     

Isolation of mannose-binding C-type lectin from sea lamprey (Petromyzon marinus) plasma and binding to Aeromonas salmonicida

The sea lamprey (Petromyzon marinus) is a parasitic cartilaginous fish of the North American Great Lakes and a predator of many bony fish species of commercial importance to the fishing industry. Mannose-binding C-type lectin (MBL) was isolated by mannan-agarose affinity chromatography from sea lamprey plasma. Mannose-binding lectin has not before been identified and quantitated in the plasma of this sea lamprey species. The affinity-purified and 2-ME reduced lamprey MBL showed two bands of 35kDa and 65kDa by SDS-PAGE and Western blotting using guinea pig anti-MBL IgG as the primary antibody. Amino acid composition analysis (mol%) of the purified lamprey MBL found high amounts of histidine, threonine, tyrosine and phenylalanine present when compared with three other vertebrate MBLs. N-terminal amino acid sequencing by Edman degradation for the first 10 residues gave XXXTKGCPDA. Lamprey plasma contained 261mug of MBL/ml of plasma. Plasma protein concentration was 40.1mg/ml. Lamprey MBL was present then in plasma at 6.5mug MBL/mg total protein. The sea lamprey MBL also specifically binds to mannose on the surface of the pathogen Aeromonas salmonicida. The presence of MBL in high concentration in lamprey plasma could be important in their innate immunity and resistance to infection. This study describes the presence of MBL in sea lamprey plasma and evidence for a C-type lectin complement pathway of innate immunity.     

The relationship between the variants of the bovine MBL2 gene and milk production traits, mastitis, serum MBL-C levels and complement activity

Mannose-binding lectin (MBL), a calcium-dependent collagenous lectin, plays an important role in the host immune defence against a wide range of pathogens. There are MBL1 and MBL2 genes which encode the MBL-A and MBL-C proteins, respectively. This study was carried out to investigate the relationship between the variants of the bovine MBL2 gene and milk production traits, mastitis, serum MBL-C levels and hemolytic complement activity in both classical pathway (CH50) and alternative pathway (ACH50) in Chinese Holstein cattle. Four single-nucleotide polymorphisms (SNPs) in the exon 1 of the MBL2 gene in Chinese Holstein cattle and Luxi yellow cattle were identified by the direct sequencing method. The SNP g.201 G>A was identified as a non-synonymous mutation (codon 31, Arg>Gln) at the N-terminus cysteine-rich domain and the SNPs g.234 C>A and g.235 G>A (codon 42) made Pro to Gln at the 1st Gly-X-Y repeat of the collagen-like domain, while the SNP g.244 T>C (codon 45) was identified as a synonymous mutation (Asn>Asn) at the 2th Gly-X-Y repeat of the collagen-like domain. The SNP markers (g.201 G>A, and g.234 C>A) were significantly correlated with somatic cell score (SCS) (P<0.05). The concentration of MBL-C protein in serum ranges from 0.8 to 7.4μg/mL by enzyme-linked immunosorbent assay. Six combinations of different haplotypes from the four SNPs were identified in Chinese Holstein cattle. Statistical analysis revealed that cows with the haplotype combination H4H5 exhibited the lowest SCS. The CH50 value of H4H5 and H5H5 cow are significantly higher than H2H5 haplotype combination (P<0.05). The association analysis results showed that the haplotype combination H4H5 may be used as a tolerance haplotype combination for the bovine mastitis.     

参与家蚕免疫反应的clip丝氨酸蛋白酶家族基因分析

丝氨酸蛋白酶在昆虫的新陈代谢和生长发育等多种生理过程中起重要作用,特别是含clip结构域的丝氨酸蛋白酶与昆虫的免疫级联激活途径密切相关。为探索家蚕clip丝氨酸蛋白酶在家蚕先天免疫反应信号通路中的作用,对家蚕(Bombyxmori)与烟草天蛾(Manduca sexta)中鉴定获得的含有clip结构域的丝氨酸蛋白酶进行序列比对和系统进化分析,发现BmSP78与MsPAP-1、BmSP127与MsHP8、BmSP124与MsHP1、BmSP125与MsHP17位于同一进化支上,4对clip丝氨酸蛋白酶的氨基酸序列相似度分别为70%、68%、81%和57%,另外的8个蛋白酶BmSP23、BmSP111、BmSP95、BmSP135、BmSP129、BmSP137、BmSP91和BmSP99构成了家蚕特有的一群clip丝氨酸蛋白酶。用革兰阴性细菌沙雷氏菌和革兰阳性细菌黑胸败血菌分别注射感染家蚕5龄第4天幼虫后,通过半定量RT-PCR检测分析clip丝氨酸蛋白酶基因在不同感染时间点的表达特征:病原菌诱导后蚕体中有11个clip丝氨酸蛋白酶基因mRNA转录水平有明显变化,其中BmSP102和BmSP96于黑胸败血菌诱导12 h后在血细胞中明显上调表达,而BmSP125在沙雷氏菌和黑胸败血菌感染12 h后的脂肪体中均明显上调表达。研究结果为建立家蚕clip丝氨酸蛋白酶可能参与的免疫级联反应路径提供了重要线索。     

旋毛虫成虫丝氨酸蛋白酶对S774A.1巨噬细胞的毒性作用

为探究旋毛虫成虫排泄分泌抗原(ES)中丝氨酸蛋白酶对宿主免疫调节作用,用PCR扩增出旋毛虫成虫期特异性丝氨酸蛋白酶基因Zh68,克隆至表达载体pET28a,转化到大肠埃希菌BL21( DE3),经诱导表达后的重组蛋白免疫接种动物获取抗血清.将抗体封闭前后的ES分别作用于S774A.1巨噬细胞,CCK-8检测巨噬细胞的增...     

Lectin agglutination for the characterization of intestinal treponema isolates from different animal species

The study presents the results of lectin-associated agglutinations of intestinal strains of treponemes isolated from pigs, dogs, mice and rats. At all 95 isolates are investigated, within the type strains for Treponema hyodysenteriae serotype 1-4 and Treponema innocens. Reactions with Concanavalin A and the Limulus-polyphemus-Lectin are often seen (twenty lectins used). Three out of four type strains for Treponema hyodysenteriae show an identical pattern of reaction, which is often seen in Treponema strains from dysentery suspected cases, too. Basing on these data a ranging in groups of lectin agglutination is proposed.     

家蚕Kazal型丝氨酸蛋白酶抑制剂基因BmSPI3的克隆与表达特征分析

Kazal型丝氨酸蛋白酶抑制剂(SPI)在机体的发育、免疫等生理过程中发挥重要的作用。从家蚕蛹cDNA文库中获得一条全长为728bp的基因序列,对该基因编码的氨基酸序列进行同源性比对,发现其蛋白具有保守的Kazal型丝氨酸蛋白酶抑制剂结构域(CⅠ-X3-CⅡ-X8-CⅢ-X14-CⅣ-X6-CⅤ-X13-CⅥ),且P1活性位点为赖氨酸(K),因此将该基因命名为BmSPI3(Gen-Bank登录号:DN237641)。通过PCR扩增BmSPI3基因,经BamHⅠ和XhoⅠ双酶切后成功构建了重组表达质粒pGEX-4T-1-BmSPI3,并转化到E.coliBL21(DE3)表达,经SDS-PAGE电泳检测在约36kD处有明显的蛋白表达条带。提取各发育时期蚕体和5龄幼虫各个组织的总RNA进行荧光定量PCR,检测结果表明:BmSPI3在5龄幼虫期表达量最高,卵期最低;在5龄幼虫表皮中的表达量最高,在马氏管的表达量最低。推测BmSPI3对胰蛋白酶和类胰蛋白酶具有抑制作用。     

The role of complement activity in the sensitivity of Salmonella O48 strains with sialic acid-containing lipopolysaccharides to the bactericidal action of normal bovine serum

Sialic acids are important constituents of animal tissue glycoconjugates and are also present in the antigens of some bacterial strains. Capsular polysaccharides with sialic acid (NeuAc) have been extensively studied with regard to sensitivity to the bactericidal action of serum, whereas little is known in this regard about lipopolysaccharides (LPS) which contain NeuAc. Strains of Salmonella O48, able to infect animals and containing the same structures of LPS with NeuAc, were examined for their susceptibility to the bactericidal action of normal bovine serum (NBS). The strains showed varied sensitivity to the bactericidal action of NBS, which indicates that the expression of LPS containing NeuAc residues is not critical for the strains' resistance to the serum's activity. In this study the mechanisms of complement activation responsible for killing serum-sensitive Salmonella O48 rods by NBS were also established. Three such mechanisms were distinguished: activation of the classical/lectin pathways, important (decisive) in the bactericidal mechanism of complement activation, parallel activation of the classical/lectin and alternative pathways, and independent activation of the classical and lectin or the alternative pathway.