牛支原体生物学特性及其膜蛋白的研究进展

牛支原体(Mycoplasma bovis,Mb)是引起牛肺炎、关节炎、乳房炎和中耳炎等众多疾病的主要病原之一,牛支原体引起的疾病在欧美地区广泛蔓延并造成巨大的经济损失。中国2008年首次报道在犊牛肺炎中分离到牛支原体,目前国内对牛支原体的认识还很欠缺,现对牛支原体生物学特性及其膜蛋白进行简要综述,以期为牛支原体病的防控与治疗提供一定的参考依据。     

牛支原体不同分离株全菌蛋白免疫印迹分析

为比较牛支原体（Mycoplasma bovis,M.bovis）不同分离株间全菌蛋白组成的差异,找到其具有免疫原性的蛋白片段,试验采用裂解液法提取分离自全国不同地区6株M.bovis分离株（W70株、1738株、Q3株、Q1株、JX02株、677株）的全菌蛋白,并利用自制抗血清对所获蛋白进行SDS-PAGE和免疫印迹分析。结果显示,6株分离株全菌蛋白条带数量、清晰度存在差异,其中W70株、1738株、Q3株和Q1株的蛋白条带数量及清晰度均优于JX02株和677株,蛋白质分子质量范围在23.2～130.8 ku之间;6株分离株均显现2条大小为55和43 ku的免疫杂交条带。综上所述,M.bovis不同分离株全菌蛋白组成存在差异,55和43 ku是其主要的免疫原性蛋白之一,该试验结果为M.bovis病血清学诊断、分子诊断技术及疫苗的研制提供理论依据。     

牛支原体药物敏感性试验

为了解牛支原体的体外药敏试验,以指导临床合理使用抗生素,对临床分离鉴定的3株牛支原体,采用微量稀释法测定其对环丙沙星、恩诺沙星、红霉素和诺氟沙星的最低抑菌浓度(MIC),重复3次,取平均值。结果表明,牛支原体对环丙沙星的MIC抑菌范围为64μg/mL～128μg/mL,对恩诺沙星的MIC值为4μg/mL～8μg/mL,对红霉素的MIC值为2μg/mL～4μg/mL,对诺氟沙星的MIC值在8μg/mL～16μg/mL之间。牛支原体对红霉素的耐药性最低,其次是恩诺沙星、诺氟沙星,对环丙沙星的耐药性最高。     

In vitro susceptibilities of field isolates of Mycoplasma agalactiae

In order to determine how widespread antibiotic resistance has become to standard treatments, the in vitro susceptibilities of 28 Mycoplasma agalactiae Spanish field isolates to 16 antimicrobial agents were determined using a broth microdilution method. The most effective antimicrobials based on minimum inhibitory concentration (MIC)₉₀ values were fluoroquinolones, tetracyclines and macrolides. Two strains were tetracycline resistant. Streptomycin, erythromycin and nalidixic acid resistance was observed in all strains.     

牛支原体新疆株的分离鉴定

为调查新疆规模化奶牛场病牛死亡原因并确定病原,本研究无菌采集7份肺炎病死牛病变肺组织样,通过牛支原体液体培养基和固体培养基分离到1株支原体,采用形态学观察和生化试验鉴定该分离株,采用支原体特异性引物和牛支原体16S rRNA通用引物扩增基因序列并测序,使用DNAStar软件将分离菌株测序结果与GenBank中的标准株序列进行同源性比对,采用Mega 6.0软件中的邻接法(Neighbor-Joining,NJ)依据16S rRNA序列构建分离株系统进化树。结果显示,分离株菌落呈典型的"煎蛋样",菌落中心凹陷深入培养基,周边菲薄而透明,经Dienes染液染色后,菌落中心呈深蓝色。该分离株不分解葡萄糖、尿素、不水解精氨酸,血细胞吸附试验和溶血试验均呈阴性,氯化三苯基四氮唑还原反应呈阳性,产生膜和斑。PCR反应扩增出大小为1 911 bp的牛支原体特异性目的片段;分离株16S rRNA基因序列与牛支原体标准株PG45的序列同源性为99.8%,与牛支原体地方株(Mb NM2012、Mb HB0801、Mb Hubei-1、Mb Ningxia-1、Mb CQ-W70和Mb 08M)的同源性为99.3%～99.7%。系统进化树显示,分离株16S rRNA基因与Mb Ningxia-1株和Mb 08M株亲缘关系较近,处于同一分支。本研究结果证实了引起病牛死亡的病原为牛支原体,为新疆牛支原体病的防治提供了科学依据。     

三株牛支原体的致病性比较

为检测从内蒙古发病牛场分离到的3株牛支原体(HS2019、HSZ2019、HSS2019)的致病性,对其进行本动物回归试验,通过观察攻毒后的临床症状、病理变化,以及应用实时荧光定量PCR确定组织器官中支原体载量,分析3株支原体的毒力.结果显示,3株牛支原体回归牛体后均使试验牛出现体温升高、咳嗽、呼吸困难等临床症状,解剖...     

牛支原体引起奶牛乳房炎的诊断

牛支原体（Mycoplasma bovis）是引起成年牛乳房炎和犊牛肺炎、关节炎的主要病原之一。本文从有乳房炎临床症状的奶牛中采集牛奶样本,经细菌培养和支原体培养、特异性PCR与环介导等温扩增（LAMP扩增）和16S rRNA测序等病原学检测证实为牛支原体感染,同时还有其他细菌的混合感染。     

重庆市某肉牛场牛支原体肺炎的诊断

重庆市某肉牛场新进育肥牛群发生以呼吸系统感染为主的传染性疾病,为确诊病因,对表现明显临床症状的病牛进行迫杀,无菌采集肺脏、肝脏、血液和心肌进行病原分离,共分离到4株菌,分别编号为CQ1、CQ2、CQ3、CQ4.经16S rRNA序列比对,CQ1与牛支原体同源性达99.9％,CQ2与羊创伤球菌同源性达99.8％,CQ3、CQ4分别与大肠杆菌和沙门氏菌同源性达99％.通过培养特性、菌落形态观察、牛支原体特异性引物PCR扩增,确定CQ1为牛支原体;药物敏感性试验和动物试验表明,该分离株对环丙沙星、氧氟沙星、四环素、壮观霉素敏感,不致死小白鼠.按牛支原体肺炎临床用药后,疫情很快得到控制,结合实验室检测结果,确认该场爆发的是以牛支原体感染为主的牛支原体肺炎.     

牛支原体疫苗的研究进展

牛支原体（Mycoplasma bovis,M.bovis）是一种造成全世界范围内育肥牛和奶牛多种疾病综合征的重要病原体。临床症状主要包括长期性肺炎及多发性关节炎（CPPS）、呼吸道疾病综合征（BRD）、乳腺炎及生殖器官疾病。牛支原体能感染多种组织和器官,也能从健康的牛体内分离,是威胁畜牧业生产的主要病原体。由于临床上抗生素治疗效果不佳,预防或控制牛支原体感染最好的选择是研发有效的商业可用的疫苗。牛支原体疫苗的研究已历经多年,虽然存在很多问题,但也取得了一定进展。文章对牛支原体弱毒疫苗、灭活疫苗及亚单位疫苗的研究进展进行了总结,并讨论了疫苗设计的优化方案,为合理设计和研发有效的牛支原体防控技术提供参考。     

牛支原体的分离鉴定及其对体外药物的敏感性分析

为探讨兽医临床治疗牛支原体肺炎常用药物的有效性,采用形态观察、分子生物学等方法对病原菌进行鉴定,共获得4株牛支原体,继而对分离菌株进行耐药性检测。结果表明,4株牛支原体均对大环内酯类抗生素耐药,对氟喹诺酮类及四环素类抗生素相对敏感。实验结果为兽医临床对牛支原体肺炎的治疗具有一定的指导意义。     

3种ELISA试剂盒检测抗牛支原体抗体的比较

为比较3种抗牛支原体(M.bovis)血清抗体的ELISA试剂盒检测效果,本实验应用3种检测M.bovis血清抗体ELISA诊断试剂盒对38份阳性样品(自然感染19份,人工感染18份)和37份阴性样品进行检测.结果表明:本实验室制备的HVRI试剂盒与商品化试剂盒Kit 1的检测结果和综合检测结果符合率分别达到92%和96%;而商品化试剂盒Kit 2的检测结果与综合检测结果符合率仅为74.67%.一致性检验结果显示:HVRI试剂盒与Kit 1的一致性较高;Kit 2与HVRI试剂盒、Kit 2与Kit 1有中度的一致性.此外,3种试剂盒对牛传染性胸膜肺炎国际标准血清(PS2)的检测结果显示HVRI试剂盒和Kit 1均为为阴性,Kit 2为阳性.因此,HVRI试剂盒与Kit 1更适于M.bovis检测和开展流行病学调查.     

Histopathological findings,phenotyping of inflammatory cells,and expression of markers of nitritative injury in joint tissue samples from calves after vaccination and intraarticular challenge with Mycoplasma bovis strain 1067

Background

The pathogenesis of caseonecrotic lesions developing in lungs and joints of calves infected with Mycoplasma bovis is not clear and attempts to prevent M. bovis-induced disease by vaccines have been largely unsuccessful. In this investigation, joint samples from 4 calves, i.e. 2 vaccinated and 2 non-vaccinated, of a vaccination experiment with intraarticular challenge were examined. The aim was to characterize the histopathological findings, the phenotypes of inflammatory cells, the expression of class II major histocompatibility complex (MHC class II) molecules, and the expression of markers for nitritative stress, i.e. inducible nitric oxide synthase (iNOS) and nitrotyrosine (NT), in synovial membrane samples from these calves. Furthermore, the samples were examined for M. bovis antigens including variable surface protein (Vsp) antigens and M. bovis organisms by cultivation techniques.

Results

The inoculated joints of all 4 calves had caseonecrotic and inflammatory lesions. Necrotic foci were demarcated by phagocytic cells, i.e. macrophages and neutrophilic granulocytes, and by T and B lymphocytes. The presence of M. bovis antigens in necrotic tissue lesions was associated with expression of iNOS and NT by macrophages. Only single macrophages demarcating the necrotic foci were positive for MHC class II. Microbiological results revealed that M. bovis had spread to approximately 27% of the non-inoculated joints. Differences in extent or severity between the lesions in samples from vaccinated and non-vaccinated animals were not seen.

Conclusions

The results suggest that nitritative injury, as in pneumonic lung tissue of M. bovis-infected calves, is involved in the development of caseonecrotic joint lesions. Only single macrophages were positive for MHC class II indicating down-regulation of antigen-presenting mechanisms possibly caused by local production of iNOS and NO by infiltrating macrophages.     

一株牛支原体的分离鉴定及致病性初步研究

对采集到的疑似牛支原体肺炎肺组织病料进行病原的分离,并对分离株进行形态学、生化和分子生物学鉴定,结果显示成功分离获得1株牛支原体,命名为NM001.该分离株的菌落形态呈典型的"荷包蛋状",不能发酵葡萄糖,不能水解精氨酸,不分解尿素.PCR能够扩增出牛支原体特异的P48基因条带,16S rRNA基因序列与Ningxia-...     

牛支原体单克隆抗体的制备与鉴定

以牛支原体(Mycoplasma bovis)湖北分离株HB0801作为抗原免疫8周龄BALB/c小鼠,利用杂交瘤技术筛选出了6株能稳定分泌抗牛支原体的单克隆抗体细胞株,分别生产腹水并对单抗进行了纯化和特性鉴定。经亚型测定,这些单抗都属IgG类。腹水ELISA效价在1×10⁵~1.6×10⁶。ELISA特异性分析结果表明,6株单抗与临床分离的牛支原体菌株以及ATCC标准株PG45都显阳性反应,但与牛的其他常见病原菌如多杀性巴氏杆菌、化脓隐秘杆菌等都显阴性反应。所有制备的单抗都与无乳支原体有交叉反应,其中两株单抗1A5和1C11只与无乳支原体有交叉反应,与其他支原体无交叉反应。经Western blotting验证,6株单抗分别识别牛支原体全菌蛋白中的不同条带,说明分别针对不同的蛋白抗原。这些牛支原体单克隆抗体为后期建立牛支原体检测方法及致病机理研究奠定了良好基础。     

2013年-2015年宁夏地区牛支原体感染的血清学调查分析

为了摸清宁夏地区肉牛和奶牛牛支原体(Mycoplasma bovis)感染情况及流行趋势,采用酶联免疫吸附试验(ELISA)对2013年-2015年采集自宁夏地区肉牛主要养殖区的57个肉牛场886份血清和奶牛主要养殖区的39个奶牛场1 088份血清进行检测.结果发现,2013年抽检的16个奶牛场阳性率为32.17％(148/460),场群阳性率100％(16/16);2014年抽检的银川地区12个奶牛场,阳性率为26.52％(61/230),场群阳性率100％(12/12);2015年抽检的11个奶牛场,阳性率为44.97％(179/398),场群阳性率100％(11/11);2014年阳性率较2013年和2015年低,2015年最高,2013年与2014年阳性率差异不显著(P>0.05),2015年与2013年和2014年的阳性率差异极显著(P<0.01).2013年抽检的19个肉牛场,阳性率为7.26％(18/248),场群阳性率为26.32％(5/19);2014年抽检的38个肉牛场,阳性率为5.02％(32/638),场群阳性率为50％(19/38);2014年较2013年的阳性率低,但差异不显著(P>0.05),而且部分地区和肉牛场未检测到牛支原体阳性血清.上述结果表明,宁夏地区奶牛养殖场牛支原体感染状况较为严重,应引起养殖场的高度重视.     

In vitro susceptibilities of field isolates of Mycoplasma mycoides subsp. mycoides large colony type to 15 antimicrobials

In vitro susceptibilities of 16 Mycoplasma mycoides subsp. mycoides large colony type field isolates to 15 antimicrobial agents were determined using a broth microdilution method. The most effective antimicrobials were fluoroquinolones, tetracyclines and macrolides, with MIC values under 2 microg/ml. Resistance to nalidixic acid, gentamicin, streptomycin and spectinomycin was observed.     

Identification and Serological Specificity of a Polysaccharide Component from Mycoplasma bovis

Whole-cell lysate and proteinase K digest preparations of the Mycoplasma bovis type strain (American Type Culture Collection 25523) were compared using sodium dodecyl sulfate polyacrylamide gel electrophoresis. Coomassie blue staining for protein revealed approximately 50 bands for the lysate but only a single band for the digest. Silver staining for polysaccharide revealed at least 19 bands for the digest. Fourteen monoclonal antibodies (MAbs) were produced using a screening procedure with an M. bovis digest. On immunoblots of digests of four M. bovis strains, an almost identical profile was seen with each strain for all 14 MAbs but differences were evident between strains. One MAb, M1557, was used to analyse 17 M. bovis strains on immunoblots. Ten to 20 bands were observed with 16 of the 17 strains, and differences were apparent among all 16 strains. In an enzyme-linked immunosorbent assay, M1557 reacted with 16 of the 17 M. bovis strains, but did not react with any of 41 non-M. bovis organisms tested. Strong reactions were observed with the MAbs and M. bovis colonies in immunofluorescence. The M. boris polysaccharide and MAbs to this component may be useful for the development of diagnostic assays for this organism.     

一起牛感染支原体与多杀性巴氏杆菌的诊断与治疗

2022年5月甘肃省某肉牛养殖场的部分犊牛,先后出现以咳嗽、呼吸急促、流鼻涕等为主的呼吸道症状,并陆续出现牛只死亡的情况,现场调查及临床检查后初步怀疑为细菌性病原感染。为进一步确诊病原并对症治疗,现场采集症状明显牛只的鼻拭子,同时对病死牛只进行解剖观察,无菌采集肺组织进行实验室病原检测。使用TaqMan探针荧光定量PCR进行3种(牛支原体、牛多杀性巴氏杆菌及牛溶血性曼氏杆菌)牛呼吸道疾病病原核酸检测。结果显示,病死牛只肺脏病变较为明显,肺尖实质化严重,上端有脂肪样颗粒状病灶;鼻拭子及肺组织呈牛支原体和多杀性巴氏杆菌核酸阳性。结果表明,该牛场本次发病是由于感染了牛支原体和牛多杀性巴氏杆菌引起的。通过采取隔离治疗、紧急免疫、严格消杀等综合性防控措施后,该牛场病情逐步好转并恢复正常生产。     

Prokaryotic Expression of NOX2 of Mycoplasma bovis and Its Adherence Characterization

To explore the biological function of NADH oxidase NOX2 from Mycoplasma bovis (Mb), according to the nox2 gene sequence of Mb strain Hubei (GenBank.CP002513.1), the primers were designed and the nox2 gene of Mb strain Lintao was amplified by PCR. Based on sequencing and gene optimization, the prokaryotic expression vector pET-nox2 was constructed, and was expressed in Escherichia coli Rosetta (DE3). Subsequently, the analysis of the enzymatic activity and the immunogenicity of recombinant proteins rMbNOX2 were completed. And then the subcellular localization of NOX2, complement-dependent bactericidal activity of anti-rMbNOX2 serum, and as well as inhibition effect of anti-rMbNOX2 serum to Mb adhering to host cells was determined. The results showed that the CDS sequence of the nox2 gene of Mb Lintao strain was 1 350 bp, and showed 99.93% homology with nox2 gene of all Mb except Mb JF4278 strain in GenBank. The result of SDS-PAGE displayed the optimized nox2 was successfully expressed in E. coli. The recombinant protein rMbNOX2 was about 67 ku. Enzyme activity analysis showed that the purified rMbNOX2 had good enzymatic activity. The results of ELISA and Western blot showed that the rMbNOX2 has excellent immunogenicity, and the Mb NOX2 distribute both in the cell membrane and cytoplasm, but it's more distributed in the cytoplasm. Complement-dependent mycoplasmacidal assay and adherence inhibition assay confirmed anti-rMbNOX2 serum has distinct complement-dependent mycoplasmacidal activity and can also effectively inhibit the adherence of Mb to host cells. The results of this study lay a foundation for further study on the biological function of Mb NOX2.     

牛支原体NOX2的原核表达及黏附特性

旨在探究牛支原体（Mycoplasma bovis,Mb）NADH氧化酶NOX2的生物学功能,本研究参照GenBank中Mb湖北分离株（Mb Hubei-1 strain）nox2基因序列设计引物,应用PCR扩增获得Mb临洮分离株的nox2基因,在测序及序列优化的基础上,构建原核表达载体pET-nox2,并在大肠杆菌Rosetta（DE3）中诱导表达,进而对表达产物rMbNOX2的酶促活性、免疫原性,NOX2在Mb内的分布,rMbNOX2抗血清的补体介导体外杀菌活性和对Mb黏附宿主细胞的抑制活性进行了分析。结果表明,Mb临洮株nox2基因全长1 350 bp,与GenBank中已知序列的Mb nox2基因序列比较,除Mb JF4278株相似性为97.93%外,其余均为99.93%。SDS-PAGE结果显示,优化的nox2基因在大肠杆菌中成功表达,重组蛋白rMbNOX2相对分子质量约为67 ku,且具有良好的酶促活性;ELISA与Western blot结果显示,rMbNOX2具有良好的免疫原性,且Mb NOX2在细胞浆中的分布多于细胞膜;补体介导的体外杀菌试验及黏附抑制试验证实,rMbNOX2抗血清具有明显的补体介导杀支原体活性,并可有效抑制Mb对宿主细胞的黏附。本研究为深入探讨Mb NOX2生物学功能奠定了基础。