胸膜肺炎放线杆菌血清8型自转运黏附素基因克隆测序及功能区对比

为研究胸膜肺炎放线杆菌(APP)三聚体自转运黏附素(TAAs)的功能,通过PCR的方法首次获得APP血清8型的基因序列并提交GenBank(bankit1392817 HQ399552),运用生物信息学的方法对APP血清8型基因序列进行分析,并与GenBank公布的已知血清型的基因序列进行比对。结果表明:与血清7型同源性达到93%;与血清3,5b型同源性均达到92%。对APP血清8型序列软件预测分析发现,含有大量的Ylhead和Hep_Hag基序,所得序列是三聚体自转运黏附素N段序列,具有良好的抗原性。     

猪胸膜肺炎放线杆菌不同菌种保存方法研究

为了寻找简便的猪胸膜肺炎放线杆菌(APP)的菌种保存方法,比较了在不同保存条件下APP菌种的存活期,结果表明:冷冻干燥法效果最好,-70℃下APP可保存2年以上;其次为绵羊脱纤血法,超低温下APP可保存1年以上,是较理想的APP简便保存法;甘油生理盐水法、血清甘油法等保存期较短,均在6个月左右,提出实验室保存APP菌种以冻干法与绵羊脱纤法交替联合使用,可有良好的菌种保存效果。     

胸膜肺炎放线杆菌Δlip40回复突变株的构建及鉴定

胸膜肺炎放线杆菌(APP)可引起猪胸膜肺炎,在一定程度上阻碍了养猪业的发展.目前,APP基因组中已得到有效鉴定的基因不足10%.为建立有效的APP功能基因研究体系,本文以前期构建的血清1型APP SLW01株外膜脂蛋白基因缺失突变株Δlip40为亲本,通过电转化法将携带有完整lip40基因的穿梭质粒pJFF-lip40导入Δlip40中,通过氯霉素抗性筛选获得回复突变株CΔlip40.对CΔlip40的生物学特性进行了初步分析发现,穿梭质粒可在APP中稳定遗传,并且APP生长能力未受穿梭质粒转入的影响.此外,SLW01和Δlip40对氯霉素高度敏感,但回复突变株CΔlip40较前两种菌株对氯霉素抗性明显增强,表明穿梭质粒pJFF224-XN抗性基因可在APP菌株中稳定表达.回复突变株CΔlip40的成功构建为分析脂蛋白Lip40致病机制提供了有效对照材料,本研究中建立的互补菌株构建系统以及APP抗性评价方法将有助于今后深入研究APP生物学特性及基因功能.     

猪传染性胸膜肺炎的诊断和防治

猪胸膜肺炎放线杆菌引起的高度传染性呼吸道疾病——猪传染性胸膜肺炎。病初精神沉郁、体温升高、不良;中期食欲废绝、粪便干燥、流产;后期咳嗽气喘、呼吸困难、耳及体侧皮肤发绀等临床症状。预防诊治主要从饲养管理、免疫接种、药物保健等方面入手。     

口腔细菌表面糖苷酶的生物学功能研究

口腔细菌是引起龋齿的关键因素。口腔细菌和黏附在牙齿表面的唾液大分子相互作用,在牙齿表面形成早期牙菌斑生物膜,随后更多的细菌加入到生物膜中生长并最终导致龋齿和牙周炎等疾病。唾液为细菌的黏附提供配体,为细菌的生长提供碳源和氮源,但是细菌如何利用以及利用哪些唾液大分子进行生长还不清楚。许多口腔细菌细胞表面和细胞内有不同的糖苷酶水解糖链。本综述总结了笔者对口腔细菌的研究,揭示不同细菌利用人的唾液生长的能力不同,有的生长良好,有的甚至不能单独在唾液中生长;而口腔共生菌Streptococcus gordonii DL1在唾液中生长良好是依赖于细菌表面的3个糖苷酶,它们捕食唾液中富含脯氨酸的糖蛋白的N-糖链,是该细菌在唾液中生长关键的第一步;而且不同的糖苷酶对底物有严格的特异性,糖链只能被依次水解。不同细菌表面有不同的糖苷酶,能够合作水解糖链从而在唾液中相互喂养并在牙齿表面共生,是笔者下一步的研究方向。     

痤疮丙酸杆菌对小鼠抗胸膜肺炎放线杆菌血清7型9型的免疫保护

为明确痤疮丙酸杆菌(PA)对具有抗胸膜肺炎放线杆菌(APP)血清7型和血清9型的异源免疫保护作用,对小鼠免疫PA分离株S14后,分别用APP血清7型(CCVC-265)和血清9型(CCVC-267)攻毒。结果表明,免疫保护率达60%和70%;而用猪抗PA血清免疫小鼠后以APP血清7型和血清9型攻毒,免疫保护率达100%。血清特异性抗体效价检测显示,PA免疫小鼠后,可诱导小鼠产生特异性的抗APP血清7型和9型的抗体,ELISA方法检测特异性抗体平均效价为1 800和2 800。PA对APP血清7型和9型的感染具有良好的保护作用。     

大肠杆菌卷曲菌毛及其致病性

大肠杆菌卷曲菌毛是其菌体表面的一种含纤维素样蛋白质附着器官,出现在大肠杆菌生理和病理过程中,可以通过黏附等作用介导大肠杆菌侵袭宿主.作为一种细菌淀粉样蛋白,卷曲菌毛有可能引起淀粉样蛋白相关疾病;卷曲菌毛可以诱导宿主炎症因子水平升高,引起脓毒血症;卷曲菌毛可以和纤维素等一起构成菌外基质,参与生物膜的形成.基于此,综述了大...     

枝原体

枝原体是一类界于细菌和病毒之间,目前所知能营独立生活的微小生物。没有细胞壁,具有明显的多形性。它们广泛地存在于人体、家畜、家禽、昆虫、植物、土壤和污水等自然环境中。枝原体能引起人、动物和植物的多种疾病,而且大都具有传染性,可使疾病迅速蔓延。比较重要的枝原体病有:人的非典型性肺炎、牛传染性胸膜肺炎、山羊传染性胸膜     

猪的7种传染病血清学调查

应用血清学方法对大武地区猪的７种传染病进行了检测。结果猪传染性胸膜肺炎为４．０８％，口蹄疫、猪瘟、猪水泡病、猪囊虫、猪形虫病等未检出。     

猪传染性胸膜肺炎的诊断与治疗

2006年2月至3月湖北省荆州市李埠、太湖、马山、纪南和曾侯等乡镇的猪场在育肥猪中爆发了一种以体温升高,精神沉郁,食欲减退,呼吸困难为特征的传染病。造成大批死亡,经实验室检查,诊断为猪传染性性胸膜肺炎,并用氟苯尼考、复方长效土霉素、复方磺胺嘧啶钠号注射液以及青霉素、盐酸环丙沙星分别对287头大中型猪传染性胸膜肺炎病畜进行对比治疗。结果显示,用氟苯尼考对大型猪和中型猪的治疗效果均为最好。60kg以上的大型猪的治愈率达97.96%,30kg~60kg的中型猪的治愈率为95.00%,平均治愈率为97.10%。     

环二鸟苷酸对细菌运动调控的研究进展

细菌中的第二信使环二鸟苷酸(c-di-GMP)对细菌的运动性有调节作用.c-di-GMP调控鞭毛的生物合成、菌毛形成和菌毛蛋白的组成,以及其他一些与运动相关的蛋白的合成.细菌的运动性与其毒力、致病性、粘附性、趋化性、生物膜组成等密切相关.在革兰氏阴性细菌中,关于c-di-GMP的信号通路的研究较为清晰,而在革兰氏阳性细菌中,关于该信号转导通路的研究较少.此外,有关c-di-GMP的信号通路的研究主要集中在病原菌.该文主要综述了一些常见病原菌中c-di-GMP对其运动性的调控机制,为研究其他细菌c-di-GMP信号通路提供思路.     

Bacteria adhesion and biofilms on surfaces

Bacterial adhesion has become a significant problem in industry and in the domicile, and much research has been done for deeper understanding of the processes involved. A generic biological model of bacterial adhesion and population growth called the bacterial biofilm growth cycle, has been described and modified many times. The biofilm growth cycle encompasses bacterial adhesion at all levels, starting with the initial physical attraction of bacteria to a substrate, and ending with the eventual liberation of cell clusters from the biofilm matrix. When describing bacterial adhesion one is simply describing one or more stages of biofilm development, neglecting the fact that the population may not reach maturity. This article provides an overview of bacterial adhesion, cites examples of how bacterial adhesion affects industry and summarises methods and instrumentation used to improve our understanding of the adhesive properties of bacteria.     

Bacterial adhesion and biofilms on surfaces

Bacterial adhesion has become a significant problem in industry and in the domicile,and much research has been done for deeper understanding of the processes involved.A generic biological model of bacterial adhesion and population growth called the bacterial biofilm growth cycle,has been described and modified many times.The biofilm growth cycle encompasses bacterial adhesion at all levels,starting with the initial physical attraction of bacteria to a substrate,and ending with the eventual liberation of cell dusters from the biofilm matrix.When describing bacterial adhesion one is simply describing one or more stages of biofilm development,neglecting the fact that the population may not reach maturity.This article provides an overview of bacterial adhesion.cites examples of how bac-terial adhesion affects industry and summarises methods and instrumentation used to improve our understanding of the adhesive prop-erties of bacteria.     

Functional genomic analysis of phagocytosis and identification of a Drosophila receptor for E. coli

The recognition and phagocytosis of microbes by macrophages is a principal aspect of innate immunity that is conserved from insects to humans. Drosophila melanogaster has circulating macrophages that phagocytose microbes similarly to mammalian macrophages, suggesting that insect macrophages can be used as a model to study cell-mediated innate immunity. We devised a double-stranded RNA interference-based screen in macrophage-like Drosophila S2 cells, and have defined 34 gene products involved in phagocytosis. These include proteins that participate in haemocyte development, vesicle transport, actin cytoskeleton regulation and a cell surface receptor. This receptor, Peptidoglycan recognition protein LC (PGRP-LC), is involved in phagocytosis of Gram-negative but not Gram-positive bacteria. Drosophila humoral immunity also distinguishes between Gram-negative and Gram-positive bacteria through the Imd and Toll pathways, respectively; however, a receptor for the Imd pathway has not been identified. Here we show that PGRP-LC is important for antibacterial peptide synthesis induced by Escherichia coli both in vitro and in vivo. Furthermore, totem mutants, which fail to express PGRP-LC, are susceptible to Gram-negative (E. coli), but not Gram-positive, bacterial infection. Our results demonstrate that PGRP-LC is an essential component for recognition and signalling of Gram-negative bacteria. Furthermore, this functional genomic approach is likely to have applications beyond phagocytosis.     

Antibacterial agents specifically inhibiting lipopolysaccharide synthesis

The spread of antibiotic resistance in Gram-negative bacteria has sustained a continuing search for new agents with antibacterial activity against this important class of bacterial pathogen. Because the biosynthesis of lipopolysaccharide (LPS) is unique to Gram-negative bacteria and required by them for growth and virulence, attempts have been made to discover or design antibacterial agents acting at this site; however, no such agents have so far been developed. We now present definitive experimental data documenting design of the first member of the class of antibacterial compounds which specifically inhibit LPS synthesis. The target enzyme is 3-deoxy-D-manno-octulosonate cytidylytransferase (CMP-KDO synthetase), a cytoplasmic enzyme which activates 3-deoxy-D-manno-octulosonate (KDO) for incorporation into LPS. A specific inhibitor of CMP-KDO synthetase, alpha-C-(1,5-anhydro-7-amino-2,7-dideoxy-D-manno-heptopyranosyl)-carboxy late was designed using results of our studies of the purified enzyme. LPS synthesis ceased and lipid A precursor accumulated, causing growth stasis and perturbation of outer membrane structure and function, following delivery of the inhibitor to the intracellular target by a peptide carrier. Antibacterial action required an intact oligopeptide permease system and specific intracellular aminopeptidase activity to release inhibitor from the peptide prodrug.     

细菌Hfq蛋白的结构、功能及作用机制

非编码小RNA(small RNA, sRNA)是细菌基因转录后调控的一个重要层次,也是近十年来原核生物研究领域的焦点之一。大多数sRNA的作用与Hfq蛋白密切相关,即Hfq可以促进sRNA与其靶标mRNA的互补配对,进而影响翻译的进行或者mRNA的稳定性。笔者对Hfq的结构、Hfq参与sRNA调节作用的机制、Hfq在多种细菌中的功能表型进行了综述。Hfq是一个保守的蛋白质,在很多细菌中广泛存在,并与真核生物中参与mRNA剪切与降解活动的Sm蛋白同源。在结构上,Hfq具有两个非等同的RNA结合面,可以结合并介导多个RNA分子的相互作用,其结构体现了和功能的高度统一性。目前,对Hfq的研究主要集中于革兰氏阴性细菌中,在革兰氏阳性细菌中,Hfq的功能尚不明晰; 此外,在许多重要的细菌中,Hfq影响功能表型的具体机制也不清楚。因此,今后有必要进一步精细研究Hfq的分子结构特征和功能特点,深入分析Hfq对细菌表型多样化的影响机制,探究Hfq影响靶标分子和功能表型的详尽机制。     

A new class of synthetic antibacterials acting on lipopolysaccharide biosynthesis

Although there is a need for antibacterial agents that act only on Gram-negative bacteria, there are at present few such compounds. The 2-deoxy analogue of beta-KDO (3-deoxy-beta-D-manno-2-octulopyranosonic acid) is a potent inhibitor of a key enzyme (CMP-KDO synthetase) in lipopolysaccharide biosynthesis of Gram-negative bacteria, but it fails to penetrate intact bacteria. Coupling an L-L-dipeptide to the 8-amino-2,8-dideoxy analogue of beta-KDO enabled it to be recognized and actively accumulated by certain peptide permeases of the cytoplasmic membrane. The dipeptide was hydrolysed in the cell and the inhibitor released. Subsequent inhibition of CMP-KDO synthetase led to the accumulation of large amounts of lipid A precursor and bacterial death. These compounds represent a new class of synthetic antimicrobials with a novel mechanism of action and considerable potential as chemotherapeutic agents.     

Protective role of phospholipid oxidation products in endotoxin-induced tissue damage

Lipopolysaccharide (LPS), an outer-membrane component of Gram-negative bacteria, interacts with LPS-binding protein and CD14, which present LPS to toll-like receptor 4 (refs 1, 2), which activates inflammatory gene expression through nuclear factor kappa B (NF kappa B) and mitogen-activated protein-kinase signalling. Antibacterial defence involves activation of neutrophils that generate reactive oxygen species capable of killing bacteria; therefore host lipid peroxidation occurs, initiated by enzymes such as NADPH oxidase and myeloperoxidase. Oxidized phospholipids are pro-inflammatory agonists promoting chronic inflammation in atherosclerosis; however, recent data suggest that they can inhibit expression of inflammatory adhesion molecules. Here we show that oxidized phospholipids inhibit LPS-induced but not tumour-necrosis factor-alpha-induced or interleukin-1 beta-induced NF kappa B-mediated upregulation of inflammatory genes, by blocking the interaction of LPS with LPS-binding protein and CD14. Moreover, in LPS-injected mice, oxidized phospholipids inhibited inflammation and protected mice from lethal endotoxin shock. Thus, in severe Gram-negative bacterial infection, endogenously formed oxidized phospholipids may function as a negative feedback to blunt innate immune responses. Furthermore, identified chemical structures capable of inhibiting the effects of endotoxins such as LPS could be used for the development of new drugs for treatment of sepsis.     

Quorum sensing in Gram-negative bacteria

Bacteria can communicate with each other by means of signal molecules to coordinate the behavior of the entire community,and the mechanism is referred to as quorum sensing (QS).Signal systems enable bacteria to sense the size of their densities by monitoring the concentration of the signal molecules.Among Gram-negative bacteria N-acyl-L-homoserine lactone (acyl-HSL)-dependent quorum sensing systems are particularly widespread.These systems are used to coordinate expression of phenotypes that are fundamental to the interaction of bacteria with each other and with their environment and particularly higher organisms,covering a variety of functions ranging from pathogenic to symbiotic interactions.The detailed knowledge of these bacterial communication systems has opened completely new perspectives for controlling undesired microbial activities.