贝类派琴虫和折光马尔太虫二重荧光定量PCR方法的建立

根据基因库中派琴虫和折光马尔太虫基因序列,设计了两对特异性引物和两条用不同荧光基团标记的TaqMan探针。对反应条件和试剂浓度进行优化,建立了能够同时检测派琴虫和折光马尔太虫的二重荧光定量PCR方法。该方法对派琴虫和折光马尔太虫的检测敏感性达到40个模板拷贝数;对派琴虫和折光马尔太虫不同浓度模板进行组合,该方法仍可有效地同时检测出这二种原虫。研究建立的派琴虫和折光马尔太虫荧光定量PCR具有特异、敏感、快速、定量和重复性好等优点,可用于临床上派琴虫和折光马尔太虫感染的检测。       

3种贝类原虫多重荧光定量PCR方法的建立

目的:建立能够同时检测单孢子虫、派琴虫和折光马尔太虫的三重荧光定量PCR方法。方法:根据基因库中单孢子虫、派琴虫和折光马尔太虫的基因序列,设计3对特异性引物和3条用不同荧光基团标记的TaqMan探针,对反应条件和试剂浓度进行优化,建立能够同时检测单孢子虫、派琴虫和折光马尔太虫的三重荧光定量PCR方法。结果:该方法对单孢子虫、派琴虫和折光马尔太虫的检测敏感性分别达到40、400和40个模板拷贝数;此外抗干扰能力强,对单孢子虫、派琴虫和折光马尔太虫不同模板浓度进行组合,仍可有效地同时检测这3种原虫,对嗜水气单胞菌、荧光假单胞菌、副溶血弧菌、溶藻弧菌、河弧菌和拟态弧菌等病原体的检测结果均为阴性。结论:建立的单孢子虫、派琴虫和折光马尔太虫多重荧光定量PCR具有特异、敏感、快速、定量和重复性好等优点,可用于临床上单孢子虫、派琴虫和折光马尔太虫感染的检测。     

狂犬病病毒TaqMan qRT-PCR检测方法的建立

建立狂犬病病毒TaqMan qRT-PCR检测方法,并进行评价和初步应用。针对狂犬病病毒L基因保守区域设计特异性引物、探针,建立PCR反应体系并评价检测体系的扩增效率、灵敏度、特异性和准确性等指标,灵敏度评价结果与现有巢式RT-PCR和基于N基因qRT-PCR检测方法相比较。结果显示本研究建立的基于L基因qRTPCR检测体系扩增效率高于90%;最小检测病毒滴度为2.7×10~(-3)FFU/mL,灵敏度高于基于N基因qRT-PCR和巢式RT-PCR 100倍;最小检测核酸拷贝数为100拷贝,建立了基于目的基因RNA标准品的标准曲线,可用于定量检测;对于我国的狂犬病病毒流行毒株检测范围较广,动物样本检测结果与金标准DFA检测结果相一致,准确性较高。本研究建立的狂犬病病毒qRT-PCR可用于狂犬病病毒实验室检测。     

不同方法检测鸡胴体中沙门菌结果的比较研究

对鸡胴体淋洗液样品进行沙门菌检测,样品经过前增菌和选择性增菌后,分别采用4种不同的方法进行检测,即普通PCR方法、实时荧光PCR方法、免疫学方法(VIDAS)和传统的微生物检验方法。共检测了56份样品,普通PCR检出阳性样品34份,实时荧光PCR阳性样品36份,VIDAS阳性样品28份;PCR和实时荧光定量PCR均无假阳性和假阴性结果。结果显示该3种检测方法均可以用于鸡胴体中沙门菌的快速检测。     

建立快速定量检测猪瘟兔化弱毒苗的荧光定量PCR技术

在猪瘟病毒兔化弱毒疫苗株的5'非编码区设计一对引物和一条荧光探针,利用荧光定量PCR原理,结合LightCycler检测系统,首次建立了定量检测猪瘟兔化弱毒苗方法.结果表明,该方法的灵敏度为102拷贝数,线性范围为107-102,达6个数量级;标准样品的变异系数为2.3%-5.1%(n=10),疫苗样品组内实验变异系数为0.85%-2.8%(n=5)、组间实验为2.5%-7.3%(n=5),对同一样品分5次RNA提取和逆转录,其变异系数为5.0%;对9份疫苗样品进行了检测,与兔体定型热反应方法相比较,有很好的相关性;整个检测过程仅需4h.该法可望取代传统的兔体定型热反应用于疫苗生产过程中的效价测定及指导疫苗的配制,也为猪瘟病毒分子生物学研究提供了一种新的、简捷有效的工具.     

Real—time TaqMan RT—PCR快速检测犬瘟热病毒方法的研究

按照犬瘟热（CDV）N基因序列,设计合成了特异性引物和探针,经各反应条件的优化,建立了Real—time荧光定量RT—PCR技术,对细胞培养物、肝脏、肺脏、脑、脾脏、淋巴结以及鼻腔拭子等组织病料中的CDV进行了特异性检测和敏感性试验。同时,利用建立的Real—time荧光定量RT—PCR方法与常规RT—PCR以及韩国BIOINDIST生产的BITRAPIDCDV检测试剂盒对57份临床样品进行了检测。结果：用20pmol／mL的引物浓度各luL和20pmol／mL的探针浓度0.3uL,获得的荧光信号最强,曲线平滑。敏感性高,可检测到1.24×3ng／uL的病毒RNA;特异性强,与NDV、AIV、NiPV等RNA病毒不发生交叉反应。试验重复性的变异系数（CV）分别为2．3％、2．5％和4.2％;与常规RT—PCR和BIOINDIST生产的BITRAPIDCDV检测试剂盒相比较,该方法具有快速、特异、敏感、可定量,并可同时检测大量样品等优点。     

北美洲流行汉坦病毒多重荧光定量RT-PCR检测方法的建立

为了建立牛轭湖病毒(Bayou virus,BAYV)、纽约病毒(New York virus,NYV)、厄尼诺洛峡谷病毒(El Moro Canyon virus,ELMCV)以及岛景病毒(Isla Vista virus,ISLAV)四种病毒快速筛查、诊断的核酸检测技术,本研究选用上述四种病毒的N蛋白基因作为靶标区域设计四组特异性引物探针,建立四重实时荧光定量RT-PCR检测方法。用四种病毒体外转录RNA进行灵敏度和重复性验证,并使用其他病毒细胞培养物及体外转录RNA进行特异性验证。结果显示,四重实时荧光定量PCR扩增效率均可达到95%以上,四种病毒体外转录RNA灵敏度介于1～10拷贝/μL,与单重检测方法无明显差异,且与其他病毒无交叉反应。稳定性评价结果显示,批内、批间变异系数均在3%以内。本研究所建立的检测方法具有良好的敏感性、特异性和重复性,可用于相关样本的诊断与筛查。     

埃博拉病毒莱斯顿亚型实时荧光定量PCR检测方法的建立

本研究的目的为建立一种灵敏、快速、定量检测埃博拉病毒莱斯顿亚型核酸的实时荧光定量PCR检测方法及试剂盒。首先选择埃博拉病毒莱斯顿亚型的保守基因NP基因作为检测靶目标,筛选出保守序列并设计合成一对特异性引物。然后将连有NP全长基因的重组质粒作为定量标准品,将10倍系列稀释的重组质粒进行荧光定量PCR扩增,绘制标准曲线,并进行重复性、灵敏度及特异性检测。结果显示建立的埃博拉病毒莱斯顿亚型荧光定量PCR检测方法,其灵敏度可达102拷贝/μL,不同梯度标准品间线性关系(R2)达0.997,斜率为-0.3101,扩增效率为110.145%,所有标准品均在79.94℃出现尖且窄的特异性熔解峰。利用该检测系统可以快速定量检测埃博拉病毒莱斯顿亚型核酸,灵敏度高、重复性好,可用于基础及临床实验室对埃博拉病毒莱斯顿亚型感染的快速诊断和临床效果的监测,具有实际的应用价值。     

狂犬病病毒 SYBR-Green玉实时荧光定量 PCR 检测方法的建立

狂犬病病毒为不分节段单链负股的 RNA 病毒,属弹状病毒科狂犬病病毒属.世界上几乎所有国家都有狂犬病发生,狂犬病病毒能够使所有温血动物发病致死,死亡率高达100%.本研究根据 GenBank 中的狂犬病病毒 M 基因序列,选择保守区域设计引物,通过对 SYBR-Green玉实时荧光 PCR 反应条件进行优化,建立了用于检测狂犬病病毒的 SYBR-Green玉实时荧光 PCR 方法.结果显示,建立的狂犬病病毒实时荧光定量 PCR 方法,具有特异性强、灵敏度高、重复性好的优点,是开展狂犬病的临床检测的有力工具.     

The Diversity of Strategies of Defense from Pathogens in Molluscs

Based on our own results and literature data, a comparative analysis is performed of particularities of mechanisms of defense from pathogens in representatives of Bivalvia and Gastropoda. The agglutinating and opsonizing activities of plasma from molluscs of phylogenetically distant species were revealed to differ significantly. These differences may be described in terms of two contrast strategies: low-promiscuous that is more typical of most gastropod mollusc species, it is characterized by a narrow specificity of plasma agglutinins and a strong dependence of phagocytosis on the presence of plasma proteins in the medium; the high-promiscuous strategy is characteristic predominately of bivalve molluscs whose plasma agglutinins are able to react with a wider spectrum of indicator cells, and the rate of phagocytosis in this case does not depend on the presence of plasma proteins in the medium. The diversity of strategies of defense from pathogens can explain differences in spectra of pathogen organisms parasitizing in Gastropoda and Bivalvia.     

An Integrated Lab-on-Chip for Rapid Identification and Simultaneous Differentiation of Tropical Pathogens

Tropical pathogens often cause febrile illnesses in humans and are responsible for considerable morbidity and mortality. The similarities in clinical symptoms provoked by these pathogens make diagnosis difficult. Thus, early, rapid and accurate diagnosis will be crucial in patient management and in the control of these diseases. In this study, a microfluidic lab-on-chip integrating multiplex molecular amplification and DNA microarray hybridization was developed for simultaneous detection and species differentiation of 26 globally important tropical pathogens. The analytical performance of the lab-on-chip for each pathogen ranged from 10² to 10³ DNA or RNA copies. Assay performance was further verified with human whole blood spiked with Plasmodium falciparum and Chikungunya virus that yielded a range of detection from 200 to 4×10⁵ parasites, and from 250 to 4×10⁷ PFU respectively. This lab-on-chip was subsequently assessed and evaluated using 170 retrospective patient specimens in Singapore and Thailand. The lab-on-chip had a detection sensitivity of 83.1% and a specificity of 100% for P. falciparum; a sensitivity of 91.3% and a specificity of 99.3% for P. vivax; a positive 90.0% agreement and a specificity of 100% for Chikungunya virus; and a positive 85.0% agreement and a specificity of 100% for Dengue virus serotype 3 with reference methods conducted on the samples. Results suggested the practicality of an amplification microarray-based approach in a field setting for high-throughput detection and identification of tropical pathogens.     

Simultaneous PCR Detection of the Two Major Bacterial Pathogens of Geranium

Xanthomonas campestris pv. pelargonii ( Xcp ) and Ralstonia solanacearum ( Rs ) are the two most important bacterial pathogens of commercially cultivated geraniums ( Pelargonium spp.), both causing bacterial wilt and leaf spot. Asymptomatic infections are important reservoirs of infections in commercial growing facilities. Our objective was to design a multiplex PCR (Polymerase Chain Reaction) assay to detect infection by either or both of these pathogens. We used a previously characterized PCR primer pair for Xcp that amplifies a region of 200 bp. In addition, we designed a new primer pair specific for Rs that amplifies a region of 822 bp. With these two primer pairs, we could detect either or both pathogens. As geranium tissue extracts frequently contain inhibitors of the PCR process, a negative PCR could result from either an accurate indication that the plant was pathogen-free or from a false negative assay. We therefore designed `amplification competence' primers, targeting a portion of the geranium 18 s rRNA gene, and generating a 494-bp amplification product that confirms amplification competence and validates a negative assay result. Thus, the triple primer pair multiplex PCR screens for the two most important bacterial pathogens of geraniums simultaneously confirms amplification competence for each geranium sample.     

Rapid Sample Processing for Detection of Food-Borne Pathogens via Cross-Flow Microfiltration

This paper reports an approach to enable rapid concentration and recovery of bacterial cells from aqueous chicken homogenates as a preanalytical step of detection. This approach includes biochemical pretreatment and prefiltration of food samples and development of an automated cell concentration instrument based on cross-flow microfiltration. A polysulfone hollow-fiber membrane module having a nominal pore size of 0.2 μm constitutes the core of the cell concentration instrument. The aqueous chicken homogenate samples were circulated within the cross-flow system achieving 500- to 1,000-fold concentration of inoculated Salmonella enterica serovar Enteritidis and naturally occurring microbiota with 70% recovery of viable cells as determined by plate counting and quantitative PCR (qPCR) within 35 to 45 min. These steps enabled 10 CFU/ml microorganisms in chicken homogenates or 10² CFU/g chicken to be quantified. Cleaning and sterilizing the instrument and membrane module by stepwise hydraulic and chemical cleaning (sodium hydroxide and ethanol) enabled reuse of the membrane 15 times before replacement. This approach begins to address the critical need for the food industry for detecting food pathogens within 6 h or less.     

A Modified PCR-Based Method for Rapid Non-Radioactive Detection of Clinically Important Pathogens

We have devised a sensitive and rapid method for the detection of several bacterial pathogens in clinical specimens using PCR. This method has been named Direct Labeling and Detection Procedure (DLDP) and is based on the direct incorporation of a nonradioactive digoxigenin label (DIG-11-dUTP) into a microbial species-specific gene fragment during amplification. Following amplification, the resulting PCR products are cleansed of nonincorporated DIG-11-dUTP, spotted onto a nylon membrane, fixed by UV-crosslinking and the labeled DNA is visualized by digoxigenin detection reagents. Using cultivated reference bacteria (Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa) we were able to demonstrate a rapid and sensitive detection of < 20 CFU of bacteria in human secretions (sputum, urine, mucous). The present study suggests that DLDP can be used as a reliable method for indication of bacteria in clinical or environmental specimens with the proviso that the selected corresponding oligonucleotide primers provide amplification of strong species-specific genes.     

Parasitism of Molluscs by Nematodes: Types of Associations and Evolutionary Trends

Although there are no confirmed fossil records of mollusc parasitic nematodes, diverse associations of more than 108 described nematode species with slugs and snails provide a fertile ground for speculation of how mollusc parasitism evolved in nematodes. Current phylogenic resolution suggests that molluscs have been independently acquired as hosts on a number of occasions. However, molluscs are significant as hosts for only two major groups of nematodes: as intermediate hosts for metastrongyloids and as definitive hosts for a number of rhabditids. Of the 61 species of nematodes known to use molluscs as intermediate hosts, 49 belong to Metastrongyloidea (Order Strongylida); of the 47 species of nematodes that use molluscs as definitive hosts, 33 belong to the Order Rhabditida. Recent phylogenetic hypotheses have been unable to resolve whether metastrongyloids are sister taxa to those rhabditids that use molluscs as definitive hosts. Although most rhabditid nematodes have been reported not to kill their mollusc hosts prior to their reproduction, some species are pathogenic. In fact, infective juveniles of Phasmarhabditis hermaphrodita vector a lethal bacterium into the slug host in which they reproduce. This life cycle is remarkably similar to the entomopathogenic nematodes in the families Steinernematidae and Heterorhabditidae. Also, the discoveries of Alloionema and Pellioditis in slugs are interesting, as these species have been speculated to represent the ancestral forms of the entomopathogenic nematodes. Development of the infective stage appears to be an important step toward the acquisition of molluscs as definitive hosts, and the association with specific bacteria may have arisen in conjunction with the evolution of necromeny.     

Rapid Detection and Identification of Nontuberculous Mycobacterial Pathogens in Fish by Using High-Resolution Melting Analysis

Mycobacterial infections in fish are commonly referred to as piscine mycobacteriosis, irrespectively of the specific identity of the causal organism. They usually cause a chronic disease and sometimes may result in high mortalities and severe economic losses. Nearly 20 species of Mycobacterium have been reported to infect fish. Among them, Mycobacterium marinum, M. fortuitum, and M. chelonae are generally considered the major agents responsible for fish mycobacteriosis. As no quick and inexpensive diagnostic test exists, we tested the potential of high-resolution melting analysis (HRMA) to rapidly identify and differentiate several Mycobacterium species involved in fish infections. By analyzing both the melting temperature and melting profile of the 16S-23S rRNA internal transcribed spacer (ITS), we were able to discriminate 12 different species simultaneously. Sensitivity tests conducted on purified M. marinum and M. fortuitum DNA revealed a limit of detection of 10 genome equivalents per reaction. The primers used in this procedure did not lead to any amplification signal with 16 control non-Mycobacterium species, thereby demonstrating their specificity for the genus Mycobacterium.     

食源性致病菌多重PCR快速检测方法建立与应用

利用PCR技术,建立多组多重食源性致病菌PCR快速检测方法。设计受试菌特异性引物,反应体系中加入多对引物和多种DNA模板,采用正交试验优化PCR反应条件,进行特异性引物的PCR扩增。建立了多组多重食源性致病菌PCR快速检测方法,方法中所检测受试菌株和模拟样品均出现特异性扩增条带,结果与实际相符。所建立多组多重PCR快速检测体系符合设计要求,可以应用于食源性突发公共卫生事件的应急检测和日常样品检测工作。     

多重PCR检测无公害畜禽肉和水产品中4种致病菌

建立无公害畜禽肉和水产品中肠出血性大肠杆菌(EHEC)、沙门氏菌、副溶血性弧菌(VP)和单核细胞增生性李斯特氏菌(LM)的多重PCR检测方法,为这些致病菌的快速诊断提供实验依据。选择分别针对EHEC溶血素基因hlyAB、副溶血性弧菌属保守序列toxR基因、沙门氏菌侵袭基因invA和LM的iap基因特异的4对引物,先分别进行单重PCR扩增,再同时加入4对引物进行多重PCR扩增,扩增产物经测序验证。建立的多重PCR方法可简便、快速、灵敏地实现对EHEC、LM、沙门氏菌和VP的同时检测,在畜禽肉和水产品中的检测灵敏度达到10^3cfu/mL。     

基于毛细管电泳的快速检测七种人冠状病毒技术方法的建立

近来,一种新型冠状病毒(SARS-CoV-2)引发的COVID-19突发疫情,给全球公众健康和社会经济构成严重威胁。SARS-CoV-2成为继人冠状病毒229E(Human coronavirus 229E,HCoV-229E)、人冠状病毒OC43(Human coronavirus OC43,HCoV-OC43)、严重急性呼吸综合征冠状病毒(Severe acute respiratory syndrome coronavirus,SARS-CoV)、人冠状病毒NL63(Human coronavirus NL63,HCoV-NL63)、人冠状病毒HKU1(Human coronavirus HKU1,HCoV-HKU1)和中东呼吸综合征冠状病毒(Middle East respiratory syndrome coronavirus,MERS-CoV)后第七种感染人类的冠状病毒。本研究以高分辨毛细管电泳技术为基础,针对七种人冠状病毒基因保守区分别设计特异性引物对,经常规PCR扩增后,通过具备单碱基差异分辨率的毛细管电泳分析,实现快速检测七种人冠状病毒的目标。通过构建基于毛细管电泳的人冠状病毒分子靶标,实现同时快速精准鉴定七种人冠状病毒的目的。本研究建立的人冠状病毒毛细管电泳快速检测技术方法具有极高灵敏性和精确性,分辨率高而且特异性好,操作简便成本低廉,为人冠状病毒的临床诊断、口岸快速检测等提供了新的技术支持。