牛结核病PCR诊断试剂盒的检测试验

应用自制牛结核病PCR诊断试剂盒对贵州省某奶牛场共计150份血样、奶样标本中结核分枝杆菌进行检测,结果显示:PCR试剂盒对111份奶样标本进行检测,8份为阳性,阳性检出率7.2%;PCR试剂盒对39份血样标本的检测,12份为阳性,阳性检出率为30.76%。本试验共计检测贵阳附近某奶牛场1 200头份奶牛,先采用PPD检测牛结核病阳性牛和可疑牛,再用PCR法进行检测,PCR检出阳性牛共计20头份,阳性检出率为1.67%;PPD检出阳性牛24头份,检出率为2%。总之,PCR试剂盒在检测牛结核病不同标本中显示出快速、特异等优点,这为今后牛结核病的检测工作提供了一条新途径。     

牛结核病诊断新技术

皮试试验是诊断牛结核病的常规方法，但由于纯蛋白质衍化结核菌素（ＰＰＤ）多次使用，会明显影响牛结核病的诊断结果。为此，英国学者利用ＥＳＡＴ－６和ＭＰＢ７０两种特异性结核病抗原建立了全血ＩＦＮ—ｒ（ｒ干扰素）试验，并评价了其诊断效果。试验采集１８０头牛血样作皮试试验检测，其中１３１头被证实患有结核病，并且１２８头来自非结核牛群。对上述血清用两种抗原建立的ＩＦＮ－ｒ试验进行检测，结果两试验具有明显的阳性相关性（Ｐ＜０．００１）。与皮试试验比较，该方法的敏感性为７６．３％，特异性为９９．２％，而皮试试验…     

用ELISA和PCR对猪,牛血清中HBV抗原,抗体及DNA的检测

用三个家生产的乙型肝炎（ＨＢ）ＥＬＩＳＡ试剂盒及聚合酶反应（ＰＣＲ）对牛、猪和羊血清分别进行了乙型肝炎病毒抗原（ＨＢＶ－Ａｇ）、抗体（Ａｎｔｉ－ＨＢＶ－Ａｂ）及ＤＮＡ的检测。ＥＬＩＳＡ共检出阳性牛血清１３份（１３／１３６），其中ＨＢ４Ａｇ阳性８份，ＨＢｅＡｇ阳性５份；阳性猪血清４份（４／３６），其中有ＨＢｅＡｇ阳性３份，ＨＢｅＡｇ阳性１份。全部阳性血清和部分阴性血清共１２０份经用ＰＣＲ检测ＨＢＶＤ     

奶牛结核病两种检测方法的比较试验

采用自制的牛结核病PCR快速诊断试剂盒,对某奶牛场100头份奶牛奶样进行检测,检出阳性牛16头;采用结核菌素皮内注射法（PPD）检出阳性牛17头,结果符合率为94.11％.用牛结核病PCR快速诊断试剂盒检测所需时间为6h,显示其快速、特异等优点,为今后牛结核病的检疫工作提供了1个新方法.     

我国规模化肉牛场牛病毒性腹泻—粘膜病流行状况监测

从山东,河南和河北省的６个规模化的肉牛场随机采肉牛血清８９份,直肠粪拭子１６５份,分别用微量细胞中和试验和双抗体夹心ＥＬＩＳＡ试剂盒检测牛病毒性腹泻－粘膜病的抗体和抗原。诊断结果;ＢＶＤ－ＭＤ中和抗体阳性率为４６．２％－６５．０％;ＢＶＤ－ＭＤ病毒抗原阳性检出率为５．１％－７７．２％。从而证实我国中原地区肉牛群中存在有ＢＶＤ－ＭＤ。     

利用聚合酶链反应技术检测牛结核杆菌病的研究

应用聚合酶链反应（ Ｐ Ｃ Ｒ） 技术检测牛结核分枝杆菌纯化 Ｄ Ｎ Ａ, 其敏感性为２５０ｆｇ 。所用引物序列对９种抗酸分枝杆菌 Ｄ Ｎ Ａ 进行扩增, 经琼脂糖凝胶电泳证实, 只有人型结核分枝杆菌、牛型结核分枝杆菌产生了３１７ｂｐ 的特异性扩增带。将 Ｐ Ｃ Ｒ 法与皮内变态反应试验（ Ｐ Ｐ Ｄ） 检测方法比较; ５４ 份血样标本中 Ｐ Ｃ Ｒ 的阳性率为１ ％ , Ｐ Ｐ Ｄ 试验的阳性率为０ 。同时对奶样标本的检测与血样结果一致。结果表明, Ｐ Ｃ Ｒ 在直接检测患牛血样、奶样标本中显示出快速、敏感、特异的优点。为今后牛结核病的检测工作提供了一条新的途径。     

二种方法检测猪传染性胃肠炎病毒抗体的比较

分别用血清中和试验和单克隆抗体阻断酶联免疫吸附试验对８１头美国进口猪轿清作猪传染性胃肠炎抗体检测。ＳＮ试验同７份阳性血清，检出率为８．６４％，Ｂ－ＥＬＩＳＡ试验检出７份ＰＲＣＶ抗体阳性血清，检出率为８．６４％，无ＴＧＥ阳性。ＳＮ试验检出７份ＴＧＥ抗体阳性血清与Ｂ－ＥＬＩＳＡ试验检出的７份ＰＲＣＶ抗体阳性血清完全重合。结果证明，应用单克隆抗体进行的Ｂ－ＥＬＩＳＡ可鉴别诊断ＴＧＥ与ＰＲＣＶ感染，优于Ｓ     

Dot—ELISA检测牛副结核病抗体的研究

本文利用提纯的副结核分枝杆菌胞浆特异性抗原，建立了检测牛副结核抗体的Ｄｏｔ－ＥＬＩＳＡ方法，用该方法对粪便培养阳性性的３２头份牛副结核病血清检测，检出２７头，阳性检出率为８４．４％，其敏感性与ＥＬＩＳＡ相似，与１０头ＯＴ变态反应阳性牛血清检测，无交叉反应。Ｍ－ｐｈｌｅｉＭ．ｆｏｒｔｕｉｔｕｍ．Ｍ．ｋａｎｓａｓｉｉ人工高兔血清经两次用Ｍ．ｐｈｌｅｉ悬液吸收，用建立的Ｄｏｔ－ＥＬＩＳＡ方法也无交叉反应     

RT—PCR与夹心ELISA检测粪便及饲料中IBDV的研究

将ＩＢＤ病鸡粪便及饲料经ＰＥＧ浓缩处理后用ＲＴＰＣＲ与单克隆抗体夹心ＥＬＩＳＡ进行ＩＢＤＶ检测。在ＲＴＰＣＲ试验中，粪便和饲料的阳性检出率均为１００％（８／８）；在夹心ＥＬＩＳＡ试验中，粪便的阳性检出率为１００％（８／８），而在饲料中末检出ＩＢＤＶ（８／８％。试验结果证明，ＲＴＰＣＲ是ＩＢＤＶ流行病学特别是传播途径研究的首选方法。     

二种方法检测猪传染性胃肠炎病毒抗体的比较

分别用血清中和（ＳＮ）试验和单克隆抗体（ＴＧＥｍＡｂ和ＴＧＥ／ＰＲＣＶｍＡｂ）阻断酶联免疫吸附试验（Ｂ－ＥＬＩＳＡ）对８１头美国进口猪血清作猪传染性胃肠炎（ＴＧＥ）抗体检测。ＳＮ试验检出７份阳性血清，检出率为８．６４％；Ｂ－ＥＬＩＳＡ试验检出７份ＰＲＣＶ抗体阳性血清，检出率为８．６４％，无ＴＧＥ阳性。ＳＮ试验检出７份ＴＧＥ抗体阳性血清与Ｂ－ＥＬＩＳＡ试验检出的７份ＰＲＣＶ抗体阳性血清完全重合。结果证明，应用单克隆抗体进行的Ｂ－ＥＬＩＳＡ可鉴别诊断ＴＧＥ与ＰＲＣＶ感染，优于ＳＮ试验     

应用TaqMan荧光定量PCR检测牛分枝杆菌

为建立快速检测牛分枝杆菌(M.bovis)的TaqMan荧光定量PCR方法,本研究以GenBank登录的M.bovis特有229 bp基因为研究对象,设计并合成引物及探针。该方法具有较好的特异性,与标准质控菌株呈阳性反应,与其他微生物样品呈阴性反应;灵敏性最低检测值可达1 pg/mL;对20阳性临床样品进行荧光定量PCR检测,均为阳性;而对培养为阴性的20份临床样品进行检测,6份为阳性。该研究结果表明,建立的方法特异性强,敏感性高,稳定性好,能够用于M.bovis的鉴别检测,对牛分枝杆菌病的快速检测和早期诊断具有重要意义。     

Isolation of Mycoplasma bovis from bovine clinical mastitis cases in Northern Greece

Mycoplasma bovis was detected in 18/219 (8.2%) quarter milk samples collected from cases of bovine clinical mastitis in Northern Greece between November 1997 and March 1999. The cases occurred in 2/37 (5.4%) of the herds examined. The micro-organism was isolated from bulk milk samples (BTS) from the two positive herds but was not isolated from 111 composite milk samples collected from clinically healthy cows from all 37 herds. Isolates were identified as M. bovis by polymerase chain reaction (PCR) assay. Other micro-organisms were also isolated from the M. bovis positive samples. The M. bovis-positive cows had all been imported into Greece from other European countries.     

奶水牛牛分枝杆菌的分离与鉴定

从患疑似结核病的广西奶水牛群中进行牛分枝杆菌的分离和鉴定。共收集了238份临床样品(鼻黏液及牛奶),病料经1.25 mol/mL NaOH溶液预处理后,接种罗氏培养基进行细菌分离。分离菌经进一步纯化后进行抗酸性染色并镜检,镜检后判为阳性的细菌再接种到鉴别培养基上进行鉴别培养,同时,应用PCR方法对镜检为阳性的细菌进行进一步的鉴别检验。结果收集的所有临床样品,经37℃培养后共获得细菌12株。这12株菌经抗酸性染色后镜检都为分枝杆菌阳性,进一步经鉴别培养基鉴定12株菌中有2株为牛分枝杆菌,其余均为非典型分枝杆菌。2株牛分枝杆菌经PCR方法鉴定得以确诊。     

牛结核病两种活体诊断方法检测结合病原学诊断的研究

本文报道应用两种活体诊断方法检测牛结核病的试验结果。2010～2011年度,应用PPD皮内变态反应方法分3批次对5156头奶牛和奶水牛实施监测,监测阳性数57头,阳性率1.11%。采集该57头牛抗凝全血,应用γ-干扰素酶联免疫吸附试验进行检测,检出阳性样品3份,阳性率5.26%。对14头第一批PPD皮内变态反应阳性牛进行病理检验和进行细菌分离培养和PCR检测,结果3份样品分离培养呈阳性,其中1份PCR鉴定为结核分枝杆菌,2份为非分枝杆菌。PCR方法检测的14份组织样品中,2份为结核分枝杆菌阳性,1份为牛结核分枝杆菌阳性。结合病理剖检和病原PCR诊断,分析比较PPD皮内变态反应试验和γ-干扰素酶联免疫吸附试验的敏感性和特异性,由于PPD纯度、非特异性反应、结果判定的主观性等因素,导致PPD皮内变态反应监测检出假阳性率较高。     

High frequency of Mycobacterium bovis DNA in colostra from tuberculous cattle detected by nested PCR

We evaluated by nested PCR reaction, different cow secretions from a herd with 48% of prevalence of bovine tuberculosis (BTB), seeking to determine niches where Mycobacterium bovis could be found. Postmortem examination of 18 (75%) tuberculin reacting cows allowed demonstrates BTB-compatible lesions in six, all of them PCR positives in milk and four in colostra samples. Our results showed that up to 62% of the colostra analysed contained M. bovis DNA, whereas only 18% of milk gave a positive reaction. Moreover, in bronchoalveolar lavages from cattle with compatible lesions in lungs or lymph nodes, where macrophages account up to 90% of cells, we did not find evidences of M. bovis. Altogether, these results suggest that differences in the anti-bacterial capacity of bovine macrophages, dependent upon microenvironment and organ-specific factors, exist. Alternatively, we hypothesize that hypoxic conditions that are encountered in mammary glands macrophages could induce M. bovis entrance into a 'dormancy-like' state, and that the high number of colostra samples were M. bovis was detected, could be an indicator of reactivation during 'peripartum'.     

Development of a real-time PCR for detection of Mycoplasma bovis in bovine milk and lung samples.

A real-time polymerase chain reaction (PCR) assay using hybridization probes on a LightCycler platform was developed for detection of Mycoplasma bovis from individual bovine mastitis milk and pneumonic lung tissues. The detection limit was 550 colony forming units (cfu)/ml of milk and 650 cfu/25 mg of lung tissue. A panel of bovine Mycoplasma and of other bovine-origin bacteria were tested; only M. bovis strains were positive, with a melting peak of 66.6 degrees C. Mycoplasma agalactiae PG2 was also positive and could be distinguished because it had a melting peak of 63.1 degrees C. In validation testing of clinical samples, the relative sensitivity and specificity were 100% and 99.3% for individual milks and 96.6% and 100% for the lung tissue. Using M. bovis real-time PCR, the M. bovis culture-positive milk samples were estimated to contain between 5 x 10(4) and 7.7 x 10(8) cfu/ml and the M. bovis culture-positive lungs between 1 x 10(3) and 1 x 10(9) cfu/25 mg. Isolation, confirmed with the real-time PCR and colony fluorescent antibody test, showed that at the herd level, the proportion of samples positive for M. bovis isolation in mastitis milk samples submitted to the Mastitis Laboratory, Animal Health Laboratory, University of Guelph, Ontario, Canada, was 2.4% (5/201). We conclude that this probe-based real-time PCR assay is a sensitive, specific, and rapid method to identify M. bovis infection in bovine milk and pneumonic lungs.     

Detection of mycoplasma in mastitic milk by PCR analysis and culture method.

Mycoplasma alkalescens, M. bovigenitalium, M. bovirhinis and M. bovis were directly detected from milk specimens by a polymerase chain reaction (PCR) when milk specimens were centrifuged and treated with mycoplasmal lysis buffer. The sensitivity of this PCR method was 110 to 1,400 colony forming units (CFU). This method was useful for the detection of mycoplasmas in milk specimens from cows at an early stage of mycoplasmal mastitis since a small amount of mycoplasma could be detect in milk without culture. The results were available within 12 hr, which is faster than conventional culture techniques. M. bovirhinis was detected in more than 70% of mastitic milk specimens when mycoplasmas were detected in milk specimens from 30 cows with mastitis by this PCR method.     

Application of different methods for the diagnosis of paratuberculosis in a dairy cattle herd in Argentina

Paratuberculosis (Ptbc) has a high prevalence in Argentina, that affects dairy and beef cattle. The culture is the gold standard to the diagnosis of the disease. Mycobacterium avium ssp. paratuberculosis (M. paratuberculosis), the aetiological agent, is difficult to isolate and grow in culture. In this study, 24 randomly selected cows of the Fresian breed from a dairy herd with a history of Ptbc were used to evaluate the performance of different diagnostic techniques. These animals did not show clinical signs of the disease. However, another animal from this herd presented evidence of clinical disease at the moment of the present study. This animal was necropsied and one strain of M. paratuberculosis was isolated from faeces, lymph nodes and intestine. Serum for indirect absorbed enzyme-linked immunosorbent assay (ELISA) and agar gel immunodiffusion (AGID) tests and whole blood samples to perform gamma interferon (gammaIFN) release assays were obtained from each animal. Faeces and milk samples to carry out bacteriological cultures, PCR identification of M. paratuberculosis, and direct examinations of smears with Ziehl-Neelsen's (ZN) stain were also collected. Tuberculin test with bovine purified protein derivative (PPD) in the caudal fold was performed. The results showed that 10 out of 24 animals (41.6%) were positive to ELISA. Eight strains of M. paratuberculosis were isolated, six from faeces, two from milk. Five of the animals that excreted the bacteria through faeces were ELISA-positive, whereas the excreters through milk were negative to ELISA. No positive samples by AGID were obtained in clinical asymptomatic animals. Seven samples gave positive gammaIFN results with avian PPD, but only two of these animals were confirmed with culture. Direct PCR, to detect IS900 (M. paratuberculosis) in faeces and milk samples, was negative, but PCR using material taken from faecal and milk cultures gave positive results before visualizing the colonies. No sample was positive by PCR directed to IS6110 (M. tuberculosis complex). There was not always agreement between isolations and ZN in the studied samples. In conclusion, the absorbed ELISA was useful to detect positive animals and excreters through faeces but not through milk. PCR applied to cultures with incipient development before the visualization of colonies was effective to specifically determine the presence of M. paratuberculosis. The gammaIFN test was not able to detect the most positive animals confirmed by culture. The importance of using ELISA and cultures is emphasized by this study but it is necessary to continue with the gammaIFN test development for early detection of the disease.