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-...     

牛巴贝斯虫GST-MSA-2c融合蛋白抗象间接ELISA检测方法的初步建立

以纯化的牛巴贝斯虫GST-MSA-2c融合蛋白作为检测抗原,通过优化ELISA反应条件,初步建立了检测牛巴贝斯虫血清特异性抗体的间接ELISA方法。方阵试验确定的GST-MSA-2C抗原的最适包被浓度为2.5μg／mL,血清最佳稀释倍数为20倍,ELISA阳性反应的临界值为OD450≥0.347,批内和批间重复试验的变异系数均小于10％。经对多例血清检测表明,所建ELSIA检测法重复性好、特异性强、灵敏度高。     

牛支原体生长曲线的测定和培养基筛选

为筛选最适于牛支原体(Mycoplasma bovis)生长的培养基,利用活菌计数方法测定了牛支原体OF2株在改良Thiaucourt’s培养基、牛心汤培养基和改良KM2培养基中的生长曲线。结果发现,牛支原体在改良Thiaucourt’s培养基中生长30 h即可达到平台期,平均最高生长滴度7.0×109ccu/mL;在牛心汤培养基中生长40 h即可达到平台期,平均最高生长滴度4.0×109ccu/mL;在改良KM2培养基中生长50 h达到平台期,其平均最高生长滴度为7.0×108ccu/mL。结果表明,牛支原体在改良Thiaucourt’s培养基中生长快、滴度高,为下一步牛支原体灭活疫苗的研究提供了参考依据。     

Effect of breed of cattle on innate resistance to infection with <i>Babesia bovis, B bigemina and Anaplasma marginale

Objective To assess the innate resistance of naive Bos taurus, Bos taurus cross Bos indicus and Bos indicus cattle to virulent Babesia bovis, B bigemina and Anaplasma marginale parasites. Design Groups of 10, pure B indicus, fi B indicus cross,/B indicus cross and pure B taurus steers were infected with virulent B bovis, B bigemina and A marginale parasites. Procedure Sequential infections were carried out by intravenous inoculation of infected blood containing 1 times 10⁸ parasites of B bovis, followed by B bigemina and then A marginale. To assess resistance, measurements were made of parasitaemia, rectal temperature, packed cell volume and the number within a group requiring chemotherapy to control infection. There was a recovery period between each infection. Results Infection with B bovis showed that pure B indicus steers were significantly more resistant to B bovis infection than the other groups, with none of this group requiring treatment. There was no significant difference between fi B indicus cross and/B indicus cross with 30% and 20%, respectively, of steers in these groups requiring treatment. The pure B taurus steers were significantly more affected then those in the other three groups with 80% requiring treatment. Infections of B bigemina produced a mild response in comparison to that of B bovis and none of the steers required treatment. However, the pure B taurus group was significantly more affected than the other three groups for all other measurements. After the A marginale infection, B indicus steers were moderately affected with 50% requiring treatment, whereas 70% of the fi B indicus group, 80% of the /B indicus cross group and 100% of the pure B taurus group required treatment. Conclusions All breeds of cattle, ranging from pure B indicus to pure B taurus may be at risk of severe disease if exposed to virulent A marginale. The results confirm that pure B indicus cattle are relatively resistant to B bovis, but there could be a significant risk of severe mortalities if cross-bred herds are exposed to virulent infection.     

Isolation of Mycoplasma bovoculi from cases of infectious bovine keratoconjunctivitis.

Five outbreaks of infectious bovine keratoconjunctivitis were examined for bacteria and mycoplasmas. Mycoplasma bovoculi was demonstrated in four of the five outbreaks. Other mycoplasmatales were represented by Ureaplasma in one sample. Moraxella bovis and Neisseria ovis were found in all the outbreaks, the former being present in the vast majority of the animals. Transmission experiments with Mycoplasma bovoculi and Moraxella bovis in combination were carried out on four young, colostrumdeprived calves. Mycoplasma bovoculi appeared to have an enhancing effect on the pathogenicity of Moraxella bovis.     

利用TB_PCR试剂盒对牛结核病的检测

应用聚合酶链式反应（ＰＣＲ）技术制备的ＴＢ－ＰＣＲ试剂盒对来自新疆６个牛场的２３８份血样、奶样、口腔分泌物标本中结核分枝杆菌进行检测,结果显示：ＴＢ－ＰＣＲ试剂盒对４０份奶样样本进行检测,７头为阳性,阳性检出率１７．５％。ＴＢ－ＰＣＲ试剂盒对１７８份血样标本的检测,２３头牛为阳性,阳性检出率为１２．９２％。ＴＢ－ＰＣＲ试剂盒对２０份口腔分泌物标本中结核分歧杆菌检测结果均为阴性。本试验中共计检测６个牛场的２３８份不同标本的ＰＣＲ阳性牛共计２７头,阳性检出率为３．０２％。将ＰＣＲ和传统的ＰＰＤ检测方法的结果比较显示ＰＰＤ检出阳性率高于ＰＣＲ,ＰＰＤ检出阳性牛３９头,检出阳性率６．７％。本试验对口腔分泌物标本的检测结果不理想。总之,ＴＢ－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。为今后牛结核病的检测     

重组牛分枝杆菌CFP-10蛋白间接ELISA检测方法的建立

[目的]建立检测牛分枝杆菌的间接ELISA方法,快速区分致病性与非致病性牛分枝杆菌,为净化牛结核病提供技术支撑.[方法]以体外扩增表达并纯化的重组牛分枝杆菌CFP-10蛋白为包被抗原,建立检测牛分枝杆菌的间接ELISA,并应用方阵法优化间接ELISA的检测条件.[结果]重组CFP-10蛋白间接ELISA的最佳检测条件为：以8μg/mL重组CFP-10蛋白包为被抗原,37℃下包被1h,再以5％脱脂奶封闭1h,血清（一抗）经1∶200倍稀释后作用1h,然后以1：500倍稀释的辣根过氧化物酶标记羊抗兔IgG（二抗）作用1h.该间接ELISA的阴阳临界值为0.281,仅与牛分枝杆菌呈阳性反应,与牛布鲁氏杆菌、牛口蹄疫病毒无交叉反应;其敏感性能检测1：320倍稀释的血清,批内与批间的变异系数均小于5.0％.[结论]建立的重组牛分枝杆菌CFP-10蛋白间接ELISA具有特异、敏感等优点,临床上可用于致病性牛分枝杆菌的检测.     

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.     

A proof of concept study to assess the potential of PCR testing to detect natural Mycobacterium bovis infection in South American camelids

Background

Cases of Mycobacterium bovis infection South American camelids have been increasing in Great Britain. Current antemortem immunological tests have some limitations. Cases at post mortem examination frequently show extensive pathology. The feasibility of detecting Mycobacterium bovis DNA in clinical samples was investigated.

Findings

A sensitive extraction methodology was developed and used on nasal swabs and faeces taken post-mortem to assess the potential for a PCR test to detect Mycobacterium bovis in clinical samples. The gross pathology of the studied South American camelids was scored and a significantly greater proportion of South American camelids with more severe pathology were positive in both the nasal swab and faecal PCR tests. A combination of the nasal swab and faecal PCR tests detected 63.9% of all the South American camelids with pathology that were tested.

Conclusions

The results suggest that antemortem diagnosis of Mycobacterium bovis in South American camelids may be possible using a PCR test on clinical samples, however more work is required to determine sensitivity and specificity, and the practicalities of applying the test in the field.     

2019年滨州地区及周边规模化场牛支原体血清流行病学调查

[目的]为了了解山东省滨州地区及周边规模化牛场支原体流行的基本情况,[方法]对该区域14个规模化奶牛场和肉牛场进行了血清采集,采用牛支原体IgG抗体ELISA检测方法进行牛支原体血清抗体检测,并使用SPSS 20进行卡方统计学检验。[结果]山东省规模化牛场的牛支原体IgG抗体总阳性率为77.86%,奶牛场的阳性率为74.29%,肉牛场的阳性率为81.43%,奶牛场牛支原体IgG阳性率与肉牛场的统计学差异不显著（P>0.05）;奶牛场不同场区,肉牛场不同场区之间,牛支原体的IgG阳性率差异显著（P<0.05）。[结论]山东省滨州地区及周边规模化牛场存在不同程度的牛支原体感染,牛支原体感染可能成为危害国内规模化奶牛场奶牛健康的主要疫病之一。