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为探明引起贵州省某鸭场雏鸭发病的病原及其致病性和耐药情况，本研究对该鸭场送的疑似细菌感染病鸭进行剖检，取鼻黏膜、心脏和肝脏等组织器官接种于培养基中进行细菌分离鉴定，通过对分离菌进行药敏试验、动物回归试验和毒力基因检测研究其耐药情况和致病性。结果显示，分离菌在血琼脂培养基上生长16 h后呈现为边缘整齐、有光泽的乳白色菌落，伴有β-溶血现象，经革兰氏染色后在生物显微镜下呈两端钝圆、弧状、排列无规则的革兰氏阴性短小杆菌，与霍乱弧菌相符；16S rDNA基因序列同源性及系统进化树显示，该分离菌与霍乱弧菌同源性高达99.6%~99.7%聚为一支；药敏试验结果显示，分离菌对大部分药物都表现为耐药，其中对氨苄西林、克林霉素、复方新诺明、苯唑西林和克林霉素等抗菌药耐药性较强，对头孢哌酮和头孢曲松敏感；动物回归试验显示，分离菌可导致试验组雏鸭5 d内全部发病死亡，表明该分离菌对雏鸭具有较强的致病性；毒力基因PCR检测结果显示，检测的霍乱弧菌相关毒力基因hlyA、ompW和chxA为阳性，而检测的O1群rfb、O139群rfb、tcpA及ctxA基因为阴性，表明本次分离的霍乱弧菌携带有致病基因，但不属于O1和O139血清群。结果表明，该鸭场雏鸭发病的疫情病原为非O1/O139血清群霍乱弧菌，该菌致病性强且对多种抗菌药物耐药。本试验结果为贵州省鸭霍乱弧菌病的防控提供了参考依据。 相似文献
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用PCR扩增了MBP—ZOT质粒上的ZOT基因，该基因编码264～399位氨基酸残基C末端的15ku △G片段，并与经改造后的质粒P^BCX、连接。将重组后的质粒PMLAG在大肠杆菌BL21中表达，将表达的目的蛋白纯化，再将p^BCX-△G片段与传染性腔上囊炎病毒VP2包涵体蛋白通过滴鼻免疫途径对14日龄SPF鸡进行联合免疫试验，分别于免疫后第10、20d采集血清样品，进行ELISA试验，检测免疫后IBD抗体效价。动物免疫试验发现：融合蛋白P^BCX △G起到了明显免疫增强效果，与VP2重组蛋白联合免疫2次后，血清IBD的VP2 IgG抗体效价是单独用VP2免疫组的3倍，明显高于空白免疫组。 相似文献
3.
C. Korsi Dumenyo Asita Mukherjee Wesley Chun Arun K. Chatterjee 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(6):569-582
N-acyl homoserine lactones (AHLs) function as cell density (quorum) sensing signals and regulate diverse metabolic processes in several gram negative bacteria. We report that strains of Pseudomonas syringae pvs. syringae (Pss), tabaci and tomato as well as P. corrugata and P. savastanoi produce difussible AHLs that activate the lux operons of Vibrio fischeri or the tra::lacZ fusion of Agrobacterium tumefaciens. In Pss strain B3A, AHL production occurs in cell density dependent manner. Nucleotide sequence and genetic complementation data revealed the presence of ahlIPss, a luxI homolog within the Ahl+ DNA of Pss strain B3A. The
DNA expresses in AHL-deficient strains of P. fluorescens and E. carotovora subsp. carotovora (Ecc), and restores extracellular enzyme production and pathogenicity in the Ecc strain. The derivatives of Pss strains B3A and 301D carrying chromosomal ahlI::lacZ do not produce AHL, but like their wild type parents, produce extracellular protease and the phytotoxin syringomycin as well as elicit the hypersensitive reaction in tobacco leaves. While these strains also produce a basal level of -galactosidase activity, the expression of ahlI::lacZ is substantially stimulated in the presence of multiple copies of the
DNA or by the addition of cell-free spent cultures containing AHL. The activation of -galactosidase production occurs with spent cultures of some, but not all Pseudomonas strains which produce AHL as indicated by the Lux and tra::lacZ assays. Pss strains deficient in the global regulatory genes, gacA or lemA, produce very low levels of AHL. Since inactivation of ahlIPss eliminates AHL production and since Ahl+ Pseudomonas strains carry the homolog of ahlIPss, we conclude that ahlIPss specifies a key step in AHL biosynthesis and it has been conserved in many plant pathogenic pseudomonads. 相似文献
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采用一种新型的引物设计方法——双启动寡核苷酸引物（dual-priming oligonucleotide,DPO）,以霍乱弧菌mdh基因为靶序列,建立了霍乱弧菌DPO-PCR特异性检测方法,分析了DPO引物退火温度不敏感性、检测灵敏度及特异性,并对检测方法进行了初步应用。灵敏度结果显示,DPO-PCR方法对霍乱弧菌的最低检出限为1.07×10^2 CFU/mL。退火温度不敏感性试验中,与常规PCR引物相比,DPO引物在45～65℃退火温度均能够高效扩增出靶基因片段。特异性结果显示,DPO-PCR方法的特异性比常规PCR方法强,不产生任何非特异性扩增。利用建立的霍乱弧菌DPO-PCR检测方法对采集的550份样本进行检测,检出43份霍乱弧菌阳性样本,经行业标准法（SN/T2425-2010）复检,检测结果相同,表明所建立的DPO-PCR检测方法具有良好的实用性,为霍乱弧菌的快速准确检测提供了新途径。 相似文献
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X.?Cui R.?HarlingEmail author 《European journal of plant pathology / European Foundation for Plant Pathology》2005,111(4):327-339
Quorum sensing is a bacterial communication mechanism by which bacteria sense their own population size and couple specific gene expression to cell density. In Gram-negative bacteria, the most commonly used quorum sensing signals are N-acyl homoserine lactones (AHLs). It is now apparent that many pathogenic bacteria employ quorum sensing to control premature expression of virulence factors. This control is thought to decrease the likelihood that the plant host would detect the pathogens presence and activate its defense system. Novel strategies that target bacterial quorum sensing systems in order to control plant bacterial diseases are discussed. 相似文献
6.
Influences of quorum‐quenching probiotic bacteria on the gut microbial community and immune function in weaning pigs 
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下载免费PDF全文 Jonggun Kim Jaepil Kim Younghoon Kim Sangnam Oh Minho Song Jee Hwan Choe Kwang‐Youn Whang Kwang Hyun Kim Sejong Oh 《Animal Science Journal》2018,89(2):412-422
The aim of this study is to investigate the dynamic gut microbial diversity in weaning swine after administering feed supplemented with probiotic bacteria that specifically inhibit the activity of quorum molecules. Initially, the universal quorum molecule autoinducer‐2 (AI‐2) bioassay results indicated that AI‐2 activity was profoundly inhibited in enterohemorrhagic Escherichia coli (EHEC) O157:H7 in the presence of Lactobacillus acidophilus strain 30SC cell extract, although the growth of EHEC was not affected. Based on plate counting results, bacterial community analysis revealed a specific reduction in coliforms compared to the control, whereas the population of lactobacilli increased in weaning swine in in vivo trials. Supplementation with L. acidophilus strain 30SC did not affect the counts of other communities, such as total aerobes and yeast/mold. In addition, PCR‐denaturing gradient gel electrophoresis analysis showed a significant difference in the 16S rRNA gene products after administering L. acidophilus strain 30SC. Selected bands were sequenced, and most of them were identified as uncultured bacterium clones or a Lactobacillus‐ and Bifidobacterium‐specific community. Therefore, our results indicate that quorum‐quenching probiotic bacteria can significantly modulate the gut microbiota of swine and these beneficial effects can contribute to the improvement of performance and health in the gastrointestinal tract of weaning pigs. 相似文献
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采用PCR方法从鱼源霍乱弧菌Y1株（Vibrio cholerae Y1）扩增毒素共调菌毛蛋白A(toxin-corcgulated pilin A,TcpA)基因并克隆至pMD 18-T载体.序列分析显示tcpA基因ORF长675 bp,编码224个氨基酸(GenBank登录号EU649677).同源性比对发现,该基因与GenBank中登录的7个霍乱弧菌参考株相应基因序列的核苷酸同源性和氨基酸同源性均很高,分别为99.6％～ 99.7％和98.7％～ 99.1％,表明TcpA蛋白相当保守.将tcpA基因亚克隆到表达载体pGEX-4T-1,并进行IPTG诱导表达,SDS-PAGE分析发现分子量约为47.0 kD的重组TcpA融合蛋白主要以包涵体形式表达.Western blot检测结果显示,重组TcpA融合蛋白可与鼠抗Vc Y1菌株菌毛蛋白抗血清发生特异性结合反应.用纯化的重组TcpA融合蛋白免疫草鱼(Ctenopharyngodon idellus)制备抗血清,双相免疫扩散试验检测抗体效价达1:16,且该抗血清能够明显抑制Vc Y1菌株对HEp-2细胞的黏附.草鱼免疫后第25天用Vc Y1菌株攻毒,结果相对免疫保护率达到73.33％.研究结果表明,组TcpA蛋白仍保留着天然菌毛蛋白的免疫原性、免疫反应性和免疫保护性,重组TcpA蛋白可作为霍乱弧菌的候选诊断抗原和疫苗抗原. 相似文献
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南美白对虾白便综合征病原霍乱弧菌的分离与药敏试验 总被引：1，自引：0，他引：1
为确定南美白对虾白便综合征的病原菌及其药物敏感性,采用传统方法从患白便综合征的南美白对虾肝胰腺中分离到病原菌菌株BB31,结合API 20E革兰阴性菌鉴定系统、16SrDNA序列及聚类分析对菌株BB31进行了鉴定,并通过纸片琼脂扩散法对菌株BB31的药物敏感性进行了测定。结果表明,菌株BB31为霍乱弧菌(GenBank登录号:KF446244),其16SrDNA序列与GenBank数据库中弧菌菌株的16S rDNA序列有99%~100%的同源性,而且与霍乱弧菌菌株RD1(GenBank登录号:KF307775)的亲缘性最近。菌株BB31对四环素、庆大霉素、恩诺沙星、氧氟沙星、诺氟沙星等抗生素的敏感性高,对磺胺甲氧嘧啶、呋喃唑酮、复方新诺明等抗生素不敏感。本研究证实霍乱弧菌是南美白对虾白便综合征的病原菌,庆大霉素、诺氟沙星等常规渔药可作为防控霍乱弧菌引起的南美白对虾白便综合征的用药参考。 相似文献
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Monchai Pumkaew Suparat Taengchaiyaphum Sorawit Powtongsook Wiboonluk Pungrasmi Kallaya Sritunyalucksana 《Journal of the World Aquaculture Society》2019,50(4):878-886
Acute hepatopancreatic necrosis disease (AHPND) causes massive mortality in shrimp ponds within the first month poststocking. The causative agent is a specific strain of Vibrio parahaemolyticus (VPAHPND) that has acquired the capability to produce virulent binary toxins called ToxA and ToxB. This study aims to test the effect of the addition of an autoinducer‐2‐containing cell‐free supernatant (CFS) from the mutant Vibrio harveyi (VH) on growth and toxin production of VPAHPND. The relative AI‐2‐like activity in CFS was detected by luminescence assay. The effect of CFS (5 and 9%) on growth and toxin production of VPAHPND was evaluated. Compared to the control culture (without CFS‐VH addition), the addition of either 5 or 9% CFS‐VH affected the growth at the initial stage of VPAHPND. Similar growth profiles of VPAHPND were found with the addition of CFS‐VH at both concentrations. Western blot analysis suggests that the addition of CFS‐VH affected the production of both toxins. ToxA could be detected at the early hour post‐CFS‐VH inoculation, whereas the high amount of ToxB was detected when 5% CFS‐VH was added. However, interfering with the AI‐2 function with furanone, the AI‐2 antagonist resulted in a slight delay in the production of both toxins. Results from this study will help to design a novel strategy to control AHPND in shrimp culture. 相似文献
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