PCR技术在支原体检测中的应用

一、前言 支原体(Mycoplasma)是界于细菌和病毒之间的原核微生物,分类学上是一个独立的纲——柔膜体纲( Mollicute)。 1989年Nocard与Roux从牛的胸膜肺炎病灶中首先分离到,以后又从病人、家畜标本中查出。迄今发现的支原体有100多种,确定对人致病的有五种。肺炎支原体(M.pneu-moniae)能引起人的原发性非典型性肺炎;解脲脲原体( Ureaplasma urealyticum)能引起非淋菌性尿道炎、绒毛膜羊膜炎、早产及低体重新生儿,人型支原体(M.hominis)主要引起肾孟肾     

支原体、衣原体、立克次体和螺旋体研究概况

支原体 支原体广泛寄生于人体、哺乳动物,鸟类及植物中,仅有少数有致病性.自1995年以来,34种支原体基因组测序已经完成或即将完成测序,已完成的包括人类致病性支原体(肺炎支原体、穿透支原体、解脲支原体等),动物致病性支原体(猪肺炎支原体、山羊传染性胸膜肺炎支原体、鸡毒支原体、牛丝状支原体、鸡滑膜支原体、鱼肺炎支原体和鼠类肺支原体),植物致病性支原体(洋葱黄化病支原体)等.肺炎支原体是人呼吸道感染的最主要病原体之一,对儿童尤其严重,因为它与人类密切相关,所以最为人们关注.     

支原体培养基的改良及其效果评价

为了改良支原体培养基配方,评价其效果。按《中华人民共和国药典》(以下简称药典)中规定的灵敏度比较方法,将实验室制备的新型支原体改良培养基与《药典》中支原体检查法推荐的处方培养基和商品化支原体培养基进行灵敏度效果比较试验。结果表明,改良后的支原体肉汤和半流体培养基,与接种口腔支原体和肺炎支原体及其它支原体的精氨酸培养基、支原体肉汤培养基无显著差异;与接种肺炎支原体的支原体半流体培养基无显著差异;与接种口腔支原体的支原体半流体培养基差异显著。因此经改良后的支原体培养基灵敏度能够满足药典规定的要求,但其操作简便,且成本低于现有的支原体培养基。     

易致污染的支原体在固体培养基上的形态特征

目的研究不同条件下、不同生长期易致污染的支原体在固体培养基中的形态特征。方法通过改变支原体菌体浓度、培养时间及培养基组成,观察支原体在固体培养基中的形态变化。结果支原体菌体浓度小于103cfu/m L时,培养至2~3天后可在固体培养基中形成典型的"油煎蛋"状形态,以蔗糖作为碳源培养支原体会导致葡萄糖发酵型支原体(肺炎支原体)不能在固体培养基中形成典型菌落,当使用牛血清代替马血清为支原体提供外源胆固醇时,猪鼻支原体在固体培养基中不能形成典型菌落。结论支原体的不同生长期、菌体浓度、培养基的组成都会使易致污染的支原体在固体培养基上的形态发生变化。     

绵羊肺炎支原体DnaK B细胞抗原表位预测及其蛋白结构分析

以绵羊肺炎支原体(Mo)热休克蛋白Hsp70(DnaK蛋白)氨基酸序列为基础,运用DNAStar软件和在线服务器等生物信息学分析工具,在同源性分析的基础上,通过Jameson-Wolf法、Kyte-Doolittle法、Emini法、Karplus-Schulz法及Welling法分别预测其抗原指数、亲水性、柔韧性、表面可极性等参数,综合分析、预测了该蛋白的B细胞抗原表位,并进行了蛋白的二级结构预测和3D结构模拟。结果表明,Mo贵州分离株的Hsp70蛋白与其它可致羊发病支原体的Hsp70蛋白同源性较低,说明该蛋白具有良好的特异性;Mo Hsp70蛋白整体抗原性较好,同时呈现较规则的空间结构,其中以C末端较稳定,区域也最大(第394-598区段),为优势B细胞抗原表位区域。     

猪肺炎支原体感染诱导的固有免疫应答研究进展

猪肺炎支原体是引起猪支原体肺炎的病原。由于缺乏成熟的猪肺炎支原体感染动物模型,使得猪肺炎支原体相关的抗感染免疫研究进展较为缓慢。本文从猪肺炎支原体感染后的炎症反应、固有免疫系统对猪肺炎支原体的识别、固有免疫细胞的作用、补体系统、抗菌肽、自噬以及细胞凋亡7个方面进行综述,旨在阐明固有免疫系统各组分在猪肺炎支原体感染中发挥的作用的研究进展,并对今后猪肺炎支原体感染的固有免疫应答研究的重点方向进行展望。     

聚合酶链反应在牛血清支原体检测中的应用

为了探讨聚合酶链反应在牛血清支原体检测上的应用价值,以支原体高度保守的rRNA操纵子(支原体基因组中16SrRNA的编码区序列)设计引物,采用碱裂解法提取牛血清中支原体DNA作为模板进行聚合酶链反应。结果表明,阳性、阴性和内控对照都扩增出了预期的条带,聚合酶链反应与支原体培养法比较,有灵敏、快速、特异性高的特点,可用于牛血清中支原体的常规检测。     

泌尿生殖道解脲支原体和人型支原体感染情况及药敏结果分析

目的分析抚顺地区泌尿生殖道解脲支原体和人型支原体感染情况及药敏情况。方法采用支原体培养、鉴定、药敏一体化试剂盒对710名患者进行解脲支原体(Uu)和人型支原体(Mh)检测和其对9种抗菌药物的药敏试验。结果710名患者中共检出支原体感染者200名,阳性率为28.17%。其中Uu 140名(19.71%),Mh 12名(1.69%),Uu+Mh混合感染48名(6.76%)。药敏结果表明,支原体对强力霉素、美满霉素和克拉霉素敏感率高,分别为95.71%、98.57%和91.42%。结论抚顺地区支原体感染发病率较高,以单纯Uu感染为主,美满霉素是治疗支原体感染的首选药物。     

2194例男性泌尿生殖道支原体检测及药敏分析

目的研究男性泌尿生殖系统炎症患者解脲脲原体(Uu)和人型支原体(Mh)感染及对抗菌药物耐药情况,以了解本地区男性支原体的感染流行状况并指导临床合理选择使用抗菌药物。方法采用支原体鉴定药敏试剂盒,对男性生殖道感染者进行支原体培养及药敏试验。结果 2 194份标本中检出支原体636例,阳性率为28.96%,其中解脲脲原体阳性率为22.59%,人型支原体阳性率为0.96%,解脲脲原体和人型支原体混合感染阳性率为5.42%。支原体对抗菌药物药敏结果显示,抗菌活性较高的是多西环素、普拉霉素、四环素和交沙霉素。结论Uu是男性泌尿生殖系统支原体感染的主要病原体。临床治疗支原体感染时应尽量根据药敏结果选择敏感药物。普拉霉素、多西环素、四环素和交沙霉素可作为本地区非淋菌尿道炎经验用药的首选药物,避免使用喹诺酮类药物。     

4103例泌尿生殖道支原体感染及药敏分析

目的通过分析泌尿生殖道支原体感染及药敏情况,为临床提供用药指导。方法采用支原体检测试剂盒进行支原体属培养和药敏试验。结果4103例患者标本中,检出支原体属1336株,总阳性率为32．56％;其中单一解脲脲原体（Uu）感染1227例,阳性率为91．84％;单纯人型支原体（Mh）感染15例,阳性率为1．12％;Uu＋Mh混合合感染94例,阳性率为7．04％。解脲脲原体对阿奇霉素、红霉素、交沙霉素、罗红霉素、米诺环素、强力霉素敏感性高;单纯人型支原体对交沙霉素、米诺环素、强力霉素敏感。结论泌尿生殖道支原体感染以Uu为主。支原体大多具有多重耐药性,临床治疗需根据药敏结果选药物。     

猴血中SFV病毒基因PCR检测方法的建立及应用

针对猴泡沫病毒SFV（Simian Foany Virus）多聚酶区（pol区）设计两对引物,以猴血DNA为模板者嵌套式PCR扩增,得到500bp左右基因片段,克隆进入pUC-19载体,经测序鉴定为SFV465bp的pol区基因片段,将此段序列与SFV各型425bp的pol区基因片段进行同源性比较,它与SFV－1型的同源性最高,为92.00%。在此基础上,用这两对引物对158例猴血DNA进行检测,阳性54例,阳性率为34.2%,发现猴群中有较高的SFV病毒的感染。     

Identification of Candida albicans by polymerase chain reaction amplification of CaYST1 gene intron fragment

A single pair of primers, deduced from the intron nucleotide sequence of the Candida albicans CaYST1 gene, was used in PCR analysis performed with both genomic DNA and whole cells of clinical isolates of Candida species and other microorganisms. All the clinical C. albicans isolates generated the expected 310 bp amplicon; other Candida species as well as laboratory strains belonging to other fungal genera failed to amplify any DNA fragment, except for Candida pseudotropicalis (amplicon of 1200 bp), Kluyveromices marxianus (amplicon of 1250 bp) and Cryptococcus neoformans (several amplicons longer than 1200 bp). Unusual C. albicans isolates from Africa also yielded the expected 310 bp amplicon. These results indicate that genes containing intron sequences may be useful to design species-specific primers for identification of fungal strains by PCR. The sensitivity of the method was evaluated for C. albicans genomic DNA by using both various DNA concentrations (224 ng to 2.7 pg) and different cell amounts (10(7); to 5 cells). The results obtained may be useful in earlier detection of candidiasis.     

Polymerase chain reaction and an outer membrane protein gene probe for the detection of Porphyromonas gingivalis

Abstract A sensitivity assay for Porphyromonas gingivalis based upon the polymerase chain reaction (PCR) was developed. A 426-bp sequence, including a Dra I- Hinc II DNA fragment (278 bp) encoding the 40-kDa outer membrane protein of the P. gingivalis gene was amplified. PCR products were obtained from chromosomal DNAs of the P. gingivalis strains tested but not from those of other oral microorganisms. The lower limit of template DNA detection was 10 pg with 30 cycles and 100 fg with 40 cycles of PCR by agarose gel electrophoresis. The PCR products were hybridized with Dra I- Hinc II DNA fragment internal to the PCR primers regions used. The lower limit of hybridization detection was 10 pg and 10 fg of template DNA with 30 and 40 cycles of PCR, respectively. These results demonstrated the simplicity, rapidity and specificity of the procedure, as well as the use of the Dra I- Hinc II DNA fragment in the identification of P. gingivalis .     

细胞质雄性不育辣椒育性恢复基因特异分子标记的筛选

利用集团分离分析法(Bulked segregant analysis BSA),以辣椒细胞质雄性不育系BU-12、恢复系RF-12为材料共筛选了336条RAPD引物,其中引物S418在恢复系中呈现特异性扩增,得到一条约3000bp的特异片段。回扩得到两条片段,测序表明大小为1515bp,1162bp。荧光原位杂交证实1515bp片段为恢复系特有,命名为S418_(1515)。序列分析表明S418_(1515)为一新发现的序列,Blastn序列比对同源性小于40%,tBlastx比对发现该序列与水稻2、4、7、10号染色体的几个BAC克隆上的序列高度同源。推测可能与其具有相似的编码功能,为进一步从分子水平研究辣椒育性恢复打下了坚实的基础。根据测序结果设计特异引物,将S418_(1515)转化成特异PCR标记,证明能用于候选材料的初筛。     

Analysis of a gene (vch) encoding hemolysin isolated and sequenced from Vibrio campbellii

This study describes the amplification, localization, and sequence analysis of a hemolysin gene from type strain V. campbellii NBRC 15631--the first report of a full-length hemolysin gene for the species. An amplicon ( approximately 600 bp) of polymerase chain reaction performed using V. campbellii DNA template and primers previously designed to target a fragment of V. harveyi hemolysin gene (vhh) was shotgun-cloned and sequenced, generating 576 bp nucleotide sequences of the V. campbellii hemolysin gene. PCR primers designed based on these initial sequences were used to amplify a 551-bp V. campbellii hemolysin gene fragment that was used as probe in Southern hybridization, which localized the complete hemolysin gene within a 3.5-kb HindIII restriction fragment of the V. campbellii genomic DNA. To obtain the remaining DNA sequences upstream and downstream of the 576-bp hemolysin gene sequences, inverse PCR was performed using a self-ligated (circularized) V. campbellii HindIII restriction fragment as the template and PCR primers designed to amplify flanking regions of the 576-bp gene fragment. Nucleotide sequences from the terminal regions of the 3.1-kb product of inverse PCR provided the flanking sequences, resulting in the complete sequence for the V. campbellii hemolysin gene. A VCH PCR primer set was designed to amplify a 1.3-kb region containing the entire hemolysin gene even from other V. campbellii strains, which was sequenced to confirm the V. campbellii hemolysin gene sequence. An open reading frame (ORF) of 1,254 bp (designated as vch) was identified, sharing 79% sequence identity with V. harveyi hemolysin gene vhh, representing 262 base substitutions between V. campbellii and V. harveyi. The deduced amino acid sequence of V. campbellii hemolysin (VCH) shows homologies to the V. harveyi hemolysin (VHH), thermolabile hemolysin of V. parahaemolyticus, proteins such as phospholipase of V. vulnificus and lecithinases of V. mimicus and V. cholerae. The VCH primer set did not produce any amplicon in PCR using V. harveyi DNA, and may therefore be used to distinguish environmental strains of V. campbellii from V. harveyi.     

Detection of cariogenic bacterial genes by microchip electrophoresis

Allele-specific PCR primers were designed, based on the dextranase (dex) gene, to identify Streptococcus mutans and Streptococcus sobrinus in dental plaque; subsequently, PCR products were detected via microchip electrophoresis (ME). In order to amplify the dex gene fragment of S. mutans and S. sobrinus, the following two PCR methods were established. Duplex allele-specific PCR primers were designed on a region of low DNA homology; furthermore, 211 and 126-bp fragments were amplified for S. mutans and S. sobrinus, respectively. Common PCR primer for single allele-specific PCR was designed so as to sandwich a region exhibiting high homology and amplify PCR product of different DNA size due to deletion of small DNA fragment in two dex genes. S. mutans and S. sobrinus were amplified, leading to the generation of 202 and 226-bp products, respectively. Analysis of DNA base size by ME in order to achieve efficient separation employed a polymer mixture consisting of hydroxypropyl methylcellulose (HPMC) and polyethylene oxide (PEO). In the presence of a polymer mixture of 0.125% PEO/0.6% HPMC, two PCR products were obtained, displaying degree of separation of 226 bp/202 bp of 2.67 (Rs). Reproducibility (CV%, n = 7) was 0.3%; additionally, separation time was approximately 85 s. This method was applied to the detection of S. mutans and S. sobrinus in dental plaque. Detection of the dex genes of S. mutans and S. sobrinus characterized by quickness, precision and high sensitivity was possible.     

Molecular detection methods developed for a systemic rickettsia-like bacterium (RLB) in Penaeus monodon (Decapoda: Crustacea)

Molecular detection methods were developed to aid in the diagnosis of a rickettsia-like bacterium (RLB) which caused severe mortalities of farm-raised Penaeus monodon in Madagascar. Using primers derived from the 16S rRNA gene of bacteria, a PCR assay was optimized to amplify this region of the genome of the RLB, using extracted DNA from infected P. monodon tissue as the template. The resulting amplified PCR product was sequenced and 2 novel primers were selected from the variable region of the gene. These primers amplified a 532 bp fragment of DNA originating from the rickettsia-infected samples. The PCR assay was optimized and tested on DNA extracted from specific pathogen-free (SPF) P. vannamei tissue and several other strains of bacteria. The PCR assay with the rickettsia-specific primers was specific for this RLB and did not amplify the other DNA samples tested. The 532 bp PCR-amplified fragment was labeled with digoxigenin (DIG) for in situ hybridization assays. This probe was tested on SPF, RLB and bacteria-infected shrimp specimens preserved in Davidson's fixative. The probe was specific for both natural and experimental rickettsial infections. Hybridization with this probe required a stringent temperature of 65 degrees C, otherwise cross-reactivity was observed with other types of bacteria.     

高产王浆西蜂DNA分子中的相关基因标志筛选及其鉴定

为了探讨西蜂与高产王浆相关特异基因标记 ,用 12种随机引物 (P1～P12 )对产王浆量不同的4品系西蜂的基因组DNA进行了RAPD PCR分析 ,分别获得了产王浆量高、低不同西蜂的DNA多态性图谱 ,并从P2 引物的DNA多态性图谱中筛选出一差异DNA片段P2 316bp .将P2 316bp差异DNA片段用地高辛标记制备成探针 ,进行Southern杂交鉴定 .实验显示 ,探针与高产王浆西蜂基因组DNA的扩增产物出现了阳性杂交信号 ,而与低产王浆西蜂基因组DNA的扩增产物未出现阳性杂交信号 .结果表明 ,该差异性基因片段P2 316bp是西蜂高产王浆优良性状相关的遗传标记 ,序列为 30 5个核苷酸 .     

Preliminary development of a diagnostic test for Brucella using polymerase chain reaction

A highly sensitive and specific diagnostic test for Brucella based on polymerase chain reaction is under development in our laboratory. A commercially available PCR kit was used to create primers that allowed the amplification of a 635 bp fragment of a 43 kDa outer membrane protein gene from Brucella abortus strain 19. We successfully amplified the cloned gene present in the pMS64 plasmid and genomic Brucella S19 DNA. The amplified DNA was easily detected by agarose gel electrophoresis. Using both the pMS64 plasmid and Br. abortus S19 purified DNA as template each component of the PCR reaction was adjusted for the optimum amplification of the DNA sequence. Optimum specific amplification resulted when the primer annealing temperature was 60 degrees C. The gene fragment was amplifiable in 25 different Brucella species and strains. To test the specificity of the reaction, DNA extracted from 17 micro-organisms possibly associated with cattle were tested. No amplification was observed. The sensitivity of the reaction was determined with different concentrations of genomic Brucella strain 19 DNA. As little as 0.1 pg DNA (less than 100 brucella cells) could be detected. The specificity and sensitivity of PCR combined with its simplicity and speed suggests the potential of this technique for routine diagnosis of brucellosis.