创伤弧菌毒力相关因子的全基因组关联分析研究

【目的】创伤弧菌是致死率最高的弧菌物种,但目前尚无在全基因组层面挖掘毒力相关因子的研究。本研究以创伤弧菌分离来源(临床和环境)作为不同表型,通过与260株基因组序列进行关联分析,挖掘毒力相关因子,从而进一步了解创伤弧菌致病因素。【方法】对139株创伤弧菌分离株进行高通量测序,获取其全基因组序列;与公共数据库已公开发表的121株基因组整合,使用pyseer软件进行全基因组关联分析,对与不同分离来源显著相关的基因进行注释和解读。【结果】共发现11个基因与临床分离株显著相关,其中9个是本研究新发现的创伤弧菌潜在毒力相关因子。【结论】本研究使用群体基因组学和统计遗传学方法,在全基因组范围扫描挖掘了创伤弧菌毒力相关因子,为深入揭示该物种致病机制、设计新的疫苗和治疗靶点提供了重要依据。     

副溶血弧菌的毒力基因表达调控的分子机制

副溶血弧菌是革兰氏阴性嗜盐细菌,是海洋脊椎动物和无脊椎动物中主要致病菌,也是引起人类急性肠胃炎、败血症和坏死性筋膜炎等疾病的主要病原体。在过去,由副溶血弧菌引起的致病感染在世界范围内有不断增加的趋势。副溶血弧菌的致病性与其自身产生的多种毒力因子有关,这些毒力因子包括粘附因子、脂多糖、溶血素、III型分泌系统、VI型分泌系统、铁摄取系统、蛋白酶、外膜蛋白等。然而,这些毒力因子的表达都受到环境因子以及宿主体内信号因子的调控。副溶血弧菌通过感知外界生存环境的各种信号因子,从而激活体内不同的信号通路,进而诱导不同的毒力因子的表达。本文主要对副溶血弧菌毒力因子表达调控的分子机制进行综述,为更好地理解宿主与病原体的相互作用对副溶血弧菌的致病机制的影响,以及为今后预防和治疗由副溶血弧菌所引起的疾病提供理论参考。     

致病性弧菌主要毒力相关因子的研究进展

弧菌(Vibrio)是一种革兰氏阴性短杆菌,其广泛分布于自然界,以水中最多.弧菌是引起人类、水生动物细菌性疾病的重要病原之一.弧菌的致病性与各个毒力基因的协同作用密切相关.弧菌的毒力因子主要可分为粘附素、内毒素、外毒素等.本文主要对致病性较强的毒力因子粘附素和外毒素进行阐述,以期为弧菌致病机理的研究及弧菌病的防治提供参考和借鉴.     

创伤弧菌溶细胞素细胞毒性机制的研究进展

创伤弧菌(Vibrio vulnificus)是一种有荚膜的革兰阴性嗜盐弧菌,存在于海水及海产品中.该菌主要引起原发性败血症和严重的创口感染.原发性败血症病人多发生低血容量性休克伴多脏器功能衰竭,病死率高.创伤弧菌感染的致病机制至今尚未完全阐明.动物实验发现该菌的毒力可能包含诸多因素,如胞外溶细胞素(VVC)、金属蛋白酶(弹性蛋白分解酶)、荚膜多糖(CPS)等.VVC是由结构基因vvhA编码的一种相对分子质量(Mr)为50 851的细胞外蛋白质,是一种能使细胞形成孔道的细胞毒素和溶血毒素,是创伤弧菌向胞外释放的唯一细胞毒素,由大多数致病菌株产生,具水溶性,对热不稳定,能溶解哺乳动物红细胞及中国仓鼠卵巢(CHO)细胞,具有血管渗透因子活性.经VVC注射的实验鼠可出现与创伤弧菌败血症病人同样的临床和病理表现,毫克以下水平即可对实验鼠致死.VVC在创伤弧菌感染致病机制中的确切地位尚有争议,但因其具有穿孔特性而颇受人们关注.目前对VVC的细胞毒性机制已有广泛研究和报道,但其确切机制尚未完全明了.本文将近年来国外有关研究的情况作一综述.     

副溶血弧菌的致病机制

副溶血性弧菌是引发微生物食源性疾病的首要病原菌,其在临床上主要引起3种疾病,即胃肠炎、伤口感染和败血症。经过多年的研究,人们对副溶血性弧菌的致病机制有了一定的认识。我们着重介绍副溶血性弧菌的主要毒力因子、毒力基因表达调控及常用的毒力表型研究方法。     

溶藻弧菌的毒力相关基因及其对小鼠的致病力

【目的】通过多重PCR检测和小鼠动物实验,对溶藻弧菌环境分离株的毒力因子进行评估,以期获得较强致病菌株和弱致病菌株之间的差别,并初步探讨该菌毒力因子对小鼠的致病机理。【方法】采用多重PCR体系检测毒力相关基因,我妻氏血平板溶血实验和平板酶活实验检测溶藻弧菌株的溶血素和胞外酶;以昆明小白鼠为实验动物,攻毒方式为灌胃和腹腔注射,根据小鼠的致病症状和死亡情况来分析和对比溶藻弧菌的胞外分泌物以及菌体本身的毒性。【结果】10株溶藻弧菌产淀粉酶、卵磷脂酶的比例为100%,脂肪酶、明胶酶次之(为70%),脲酶均未被检出;神奈川现象阳性菌株率为60%。毒力基因检测的结果显示10株溶藻弧菌中toxR、Collagenase、tlh、FlaA、ompW、AspA、fur这些与毒力有关的基因均有分布,而toxS、trh、tdh、UreR并未检出。10株溶藻弧菌中的VA009对小鼠显示了较强的致病性,能造成腹腔积液,经腹腔注射感染此菌后7 d内死亡率高达80%。【结论】不同的溶藻弧菌对小鼠的致病性存在较大差异,溶藻弧菌菌体本身比胞外分泌物对其毒性的贡献要大,而副溶血弧菌的毒性则由其胞外分泌物起主要作用;比较我们筛选出的强致病菌株与弱致病菌株,其上述毒力基因的分布并没有差别,说明溶藻弧菌可能存在一套与副溶血弧菌不同的独立的毒力基因系统。     

鳗弧菌毒力相关基因的研究进展

鳗弧菌是引起多种海水鱼类出血性败血症的病原菌。其致病机理与各个毒力基因的协同作用密切相关。文中综述了鳗弧菌的主要毒力基因,包括编码外毒素、粘附因子、侵袭因子、细胞表面成分以及铁吸收系统的基因和部分检测方法。     

鳗弧菌毒力相关基因的研究进展

鳗弧菌是引起多种海水鱼类出血性败血症的病原菌。其致病机理与各个毒力基因的协同作用密切相关。文中综述了鳗弧菌的主要毒力基因,包括编码外毒素、粘附因子、侵袭因子、细胞表面成分以及铁吸收系统的基因和部分检测方法。     

副溶血弧菌毒力评价小鼠模型的建立与应用

目的建立用于评价副溶血弧菌毒力的小鼠模型,为研究副溶血弧菌的致病机制奠定基础。方法将适宜浓度的菌液经腹腔感染4～5周龄雌性BALB/c小鼠,观察小鼠的症状及死亡数。结果高盐(2%NaCl)条件下培养的强毒株RIMD2210633,经腹腔感染107CFU的菌量,小鼠存活率为20%～30%,而环境无毒株S251的小鼠存活率为100%。结论建立了评价副溶血弧菌毒力的实验小鼠模型,并应用于不同盐分浓度培养的强毒株与环境无毒株的毒力比较实验。     

黄颡鱼拟态弧菌的鉴定、毒力相关因子及药敏特性

2018年浙江省黄颡鱼主养区暴发了严重的溃疡病, 为查明该病的病原特点, 了解病原的致病因子及药物敏感性, 对溃疡黄颡鱼(Pelteobagrus fulvidraco)上分离的多株优势菌, 分别采用生理生化特性和管家基因16S rRNA、pyrH的系统进化树进行分类鉴定, 通过人工回归感染试验分析菌株的病原性, 利用平板法测定相关的毒力因子并采用PCR法对毒力相关基因进行检测, 应用微量二倍稀释法测定14种抗菌药物的最小抑菌浓度。结果表明, 11株优势菌皆为拟态弧菌, 2株代表菌腹腔注射感染黄颡鱼后均可引发溃疡症状; 11株拟态弧菌均具有溶血活性、蛋白酶、明胶酶和DNA酶活性, 不具有卵磷脂酶活性, 可分泌产生铁载体; 所有菌株均携带vmh、ompU、toxR及matCDB-iucABCD-iutA等毒力相关基因, tcpA、ctxA、st、zot、ace、tdh等毒力基因均未检出。各菌株对氨苄青霉素、磺胺嘧啶、磺胺甲噁唑、磺胺间甲氧嘧啶高度耐药, 对环丙沙星、恩诺沙星、氟苯尼考、多西环素、土霉素、甲砜霉素、红霉素、交沙霉素、磺胺二甲氧嘧啶较敏感, 个别菌株对新霉素和甲砜霉素耐药。以上研究结果表明, 拟态弧菌感染可引起黄颡鱼溃疡病, 不同发病养殖场的分离株具有相同的表型特征及毒力基因型, 并具有较一致的生理生化特性和耐药谱型, 说明它们具有相同的遗传背景或传染源。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细