牛支原体病实验室诊断技术研究进展

牛支原体病是由牛支原体引起的以肺炎、关节炎、乳腺炎等为主要症状的传染病，该病分布范围广，给养牛业造成了巨大经济损失。当前尚无有效的疫苗防治牛支原体病，但快速且准确的诊断方法能够预防和控制该病的流行。本文就牛支原体病的病原学诊断、免疫学诊断、血清学诊断和分子生物学诊断方法进行综述，旨在为该病的诊断和治疗提供参考依据。     

牛支原体病研究进展

牛支原体病是由牛支原体引起的,以肺炎、结膜炎、关节炎、中耳炎等为主要临床症状的疾病,世界范围内普遍存在。牛支原体的致病机理和毒力相关因子还不是很清楚,但有研究发现可变表面脂蛋白、黏附因子等可能与致病性相关。目前国内外用于确诊牛支原体病的主要方法包括病原体的分离鉴定、核酸诊断和血清学检测等;牛支原体疫苗被认为可以刺激机体产生可检测的Ig M、Ig G1、Ig G2、和Ig A等抗体反应。预防该病可通过加强牛群引进及饲养管理,对已发病牛群进行疫病控制与治疗等综合防控措施来实现。     

牛支原体病的研究进展及防控措施

牛支原体感染可引起牛呼吸系统综合征、结膜炎、中耳炎、乳腺炎、关节炎甚至流产等疾病,给各国养牛业带来重大经济损失。由于目前尚无疫苗及有效的药物可用于该病的防治,及时诊断牛支原体病有利于牛场采取有效的措施以降低扩散风险,减少经济损失。本文就牛支原体病病原、常见的生存环境、支原体的鉴别、临床感染、防控措施的研究进展等方面进行综述,供同行参考。     

种猪场猪支原体肺炎流行病学调研

猪支原体肺炎在我国广泛流行，为查清该病在山西省流行情况，对部分种猪场和散养户进行了流行病学调研，证实猪群咳嗽、气喘现象较为普遍；对疑似病猪、死猪采集病料，用PCR试剂盒检测猪肺炎支原体病原阳性率为26％以上；对非免疫猪群抽检血样，用ELISA试剂盒检测猪肺炎支原体血清抗体阳性率为36．7％以上。以上调研证明，山西种猪场猪支原体肺炎感染较为严重，与临床调查结果基本相符。可能与山西昼夜温差大，养猪户只重视保温、不重视通风，绝大多数养猪户不接种猪肺炎支原体疫苗有一定关系。为今后山西省防治该病提供了重要依据。     

两种猪支原体肺炎灭活疫苗的临床效果对比

猪支原体肺炎又名"猪喘气病",对养猪业危害巨大,疫苗免疫是预防该病最有效的方式。为了评估市场上两种猪支原体肺炎疫苗的临床效果,本试验从仔猪日增重、成活率、料肉比以及血液抗体水平等方面进行了对比,结果表明试验组支原体灭活苗的效果要优于对照组。     

牛传染性支原体肺炎综合防治措施

正牛传染性支原体肺炎是一种由牛支原体感染引发的以坏死性肺炎为主要临床特征的接触性牛呼吸道疫病。该病对养牛业的发展有较大的危害,一旦牛群有该病感染,较短时间内难以消除病原体,且对该病的疫苗研究以及检疫方式、措施尚不完善,同时,该病的病原体对抗生素敏感性较低,导致该病难以防治,对养殖户会造成较大的经济损失。本文从该病的病原、流行病学、临床症状、病理变化、诊断以及综合防治措施进行综述。1病原     

牛支原体相关疾病的防治方法

牛支原体是一种病原体,对牛的生长状况有很大的威胁,但容易被忽视,其能够导致乳腺炎、牛肺病、关节炎等多种疾病,我国已经证实了该病所引发的各种并发症,给养牛业造成了较大的经济损失。文章主要分析探讨了内蒙古地区牛养殖过程中出现的牛支原体病等相关疾病的防治工作,从牛支原体相关疾病、传播与检测以及预防工作等方面进行阐述,以此为我国牛支原体病的防治提供参考。     

猪支原体肺炎疫苗研究进展

猪肺炎支原体是引起猪支原体肺炎的病原,该病呈世界性流行,死亡率虽然不高,但由于长期性和消耗性的流行,使饲料转化率降低,并引起猪的多种并发病,是造成养猪业经济损失最重要的疾病之一。目前疫苗免疫是预防猪支原体肺炎和减少经济损失最有效的手段之一,猪支原体肺炎疫苗主要有灭活疫苗和减毒活疫苗。这些疫苗已得到广泛的应用,并在临床上取得了较好的免疫效果。而基因工程疫苗由于自身的优点和可行性则会成为未来疫苗研发的趋势,粘附因子在病原粘附上起到非常直接的作用,将单个或多个粘附因子引入基因工程疫苗中会大大提高疫苗的免疫反应。另外,噬菌体展示技术和多肽疫苗技术也被用于新型猪支原体肺炎疫苗的研究开发中。本文综合了近年来国内外猪支原体肺炎疫苗的应用情况和处于不同研究阶段的疫苗,并重点关注基因工程疫苗和新型联合疫苗的研究,以期为行业研究提供参考。     

猪支原体肺炎疫苗应用现状与研究进展

猪支原体肺炎是造成养猪业经济损失最大的传染病之一,严重危害养猪业健康发展。疫苗免疫防治该病极为关键。本文就该病在疫苗方面的应用现状与研究进展展开综述,为有效防控该病提供参考。     

不同物种支原体的比较基因组学研究

为了研究不同物种支原体在进化关系、结构组成以及致病因子三方面所存在的异同,试验采用比较基因组学的方法,分析了不同物种来源的21株支原体的进化关系,并以肺炎支原体为例,对来自三个不同物种(猪、牛、羊)的代表株在基因组的组成结构以及整体相似程度方面进行了横向比较分析,并进一步利用相似性比较对这三个物种代表株进行潜在的毒力因子挖掘。结果表明:三个不同物种的肺炎支原体差异较大;猪肺炎支原体内毒力因子的保守性和特异性都较高,牛支原体和山羊支原体中存在较多相似的毒力因子。说明以不同宿主寄生的致病型支原体结构组成上变异较大,但羊与牛的肺炎支原体在致病机理上可能更为相近。     

Increased prevalence of Mycoplasma bovis in the Netherlands.

The epidemiology, therapy, and prevention of M. bovis infections are briefly reviewed. In a survey begun in 1982, M. bovis was found frequently in the respiratory tract [corrected] of veal calves and beef cattle with respiratory problems. In replacement calves infected with respiratory disease in dairy herds, however, the organism has only been detected since 1986. Respiratory tract specimens collected from calves with respiratory disease were submitted for examination for M. bovis from 1986 to 1991 and originated from 83 herds. Mycoplasma bovis was detected in specimens from 59 of the herds, 20% of which were dairy herds and 80% fattening herds. Arthritis caused by M. bovis was observed in 12 herds until July 1991. Since 1976 when the first mastitis outbreak caused by M. bovis was diagnosed, M. bovis has caused 14 more outbreaks. The number of diseased cattle varied from 1 tot 16 per farm, and clinical signs of mastitis varied from mild to severe. In all instances the infection has been eradicated from the herds. Because M. bovis can cause great losses in intensively reared cattle herds, it is advisable to separate purchased veal calves and beef cattle from dairy cattle to prevent further spread of M. bovis.     

Method for evaluation of Mycobacterium bovis purified protein derivative tuberculin in experimentally infected cattle.

A method for the evaluation of Mycobacterium bovis purified protein derivative (PPD) tuberculin in experimentally infected cattle is presented. The development of skin test responses in M bovis-infected cattle was determined for International Standard PPD-S, M bovis PPD-2, and M bovis PPD-5 at 24, 48, and 72 hours. Significantly larger reactions (dermal thickness) were observed at 48 and 72 hours than at 24 hours (P = 0.001). Statistically significant differences were not detected in the responses obtained with M bovis PPD-2, M bovis PPD-5, and International Standard PPD-S if comparisons were made at approximately the same concentrations in M bovis-infected cattle (P greater than 0.25). In Mycobacterium avium-infected cattle, M bovis PPD-2 produced skin test responses that were significantly smaller than responses obtained using M avium PPD-2 (P = 0.001). Significant variation was not observed in the PPD-S responses in 2 groups of M bovis-infected cattle (P greater than 0.1).     

一例奶牛发生牛支原体肺炎的诊断

牛支原体是严重影响养牛业发展的重要病原。2008年我们报道牛支原体导致＂肉牛传染性牛支原体肺炎＂以来,主要在肉牛发现该病。本文从临床出现类似症状的运输后发病奶牛采集样本,经细菌培养和支原体培养、特异性PCR扩增和16S rRNA测序等病原学检测证实为牛支原体感染。     

Lymphocyte subset proliferative responses of Mycobacterium bovis-infected cattle to purified protein derivative

Despite highly successful eradication efforts in several countries, Mycobacterium bovis infection of cattle remains a significant health concern worldwide. Immune mechanisms of resistance to and/or clearance of M. bovis infection of cattle, however, are unclear. Recent studies have provided evidence supporting a role for CD4(+), CD8(+), and gammadelta TCR(+) T cells in the response of cattle to M. bovis. In the present study, we utilized a flow cytometric-based proliferation assay to determine the relative contribution of individual lymphocyte subsets in the response to M. bovis infection and/or sensitization with mycobacterial purified protein derivative (PPD). Peripheral blood mononuclear cells (PBMC) from M. bovis-infected cattle proliferated in response to in vitro stimulation with M. bovis PPD. CD4(+) T cells and gammadelta TCR(+) cells were the predominate subsets of lymphocytes responding to PPD. gammadelta TCR(+) cells also proliferated in non-stimulated cultures; however, the gammadelta TCR(+) cell proliferative response of infected cattle was significantly (p<0.05) greater in PPD-stimulated cultures as compared to non-stimulated cultures. Intradermal injection of PPD for comparative cervical testing (CCT) induced a boost in the in vitro proliferative response of CD4(+) but not gammadelta TCR(+) cells of infected cattle. Administration of PPD for CCT also boosted interferon-gamma (IFN-gamma) production by PBMC of infected cattle following in vitro stimulation with M. bovis PPD. Injection of PPD for CCT did not, however, elicit a proliferative or IFN-gamma response in cells isolated from non-infected cattle. These data indicate that CD4(+) and gammadelta TCR(+) cells of M. bovis-infected cattle proliferate in a recall response to M. bovis PPD and that the CD4(+) cell response is boosted by intradermal injection with PPD for CCT.     

New generation vaccines and delivery systems for control of bovine tuberculosis in cattle and wildlife

Advances in the understanding of protective immune responses to tuberculosis are providing opportunities for the rational development of improved vaccines for bovine tuberculosis. Protection requires activation of macrophages through stimulation of a Th 1 type immune response. Ideally, a vaccine for cattle should induce protection without causing animals to react in a tuberculin test when exposed to Mycobacterium bovis. A number of new tuberculosis vaccines including attenuated M. bovis strains, killed mycobacteria, protein and DNA vaccines have been developed and many of these are being assessed in cattle. The requirements for a tuberculosis vaccine for wildlife differ from those for cattle. The major goal of a wildlife vaccine is to prevent the transmission of M. bovis to cattle and other wildlife. Although there are a number of technical problems associated with the development of a vaccine delivery system for wildlife, attenuated M. bovis vaccines administered via oral baits or aerosol spray to possums have already been shown to reduce the severity of a subsequent M. bovis infection.     

Mycoplasma bovis-free breeding of cattle]

On a cattle farm latently infected by M. bovis, field studies aiming at the formation of a mycoplasma free herd, were carried out with a group of newborn female calves. These calves were strictly separated from their dams and any other cattle immediately after parturition. Intensive investigations for mycoplasmas were made over 30 months (mycoplasma isolation from nasal swabs, antibody detection by means of indirect hemagglutination test and ELISA technique). M. bovis could never be isolated from the samples. Also, there were no antibodies to M. bovis. In some animals antibody titers to M. bovis occurred after having contact with cattle infected with M. bovis. The results demonstrate a practicable way to establish cattle herds free from M. bovis infection.     

Spatial relationship between Mycobacterium bovis strains in cattle and badgers in four areas in Ireland

We investigated whether strains (restriction fragment length polymorphism, RFLP-types) of Mycobacterium bovis isolated from badgers and from cattle clustered among and within four areas in Ireland. The spatial scan test and nearest-neighbor analysis were used as the spatial cluster-detection techniques. In addition, for each of the major strains, associations between the distance to badger setts and the "centroid" of the cattle farm were assessed in a logistic model. Overall, between September 1997 and May 2000, 316 and 287 M. bovis samples, from badgers and cattle, respectively, were strain-typed. The distribution of strains in badgers, and separately in cattle, differed among areas. Within each of the four large areas, badgers and cattle tended to have similar strains; this is consistent with the sharing of M. bovis strains within an area. In more detailed within-area analyses, some spatial clusters of M. bovis strains were detected, separately, in both cattle and badgers. Almost half of the infected badger setts with a specific strain were located outside of the "detected" clusters. There was no association between the number of infected badgers with a specific M. bovis strain within 2 or 5 km distances to cattle herds, and the risk of the same strain in cattle. We speculate about the dynamic nature of badger movements, as an explanation for the absence of more clusters of most of the strains of M. bovis isolated from badgers, and its impact on trying to study transmission of M. bovis between cattle and badger.     

Cattle-to-cattle transmission of bovine tuberculosis

In developed countries, Mycobacterium bovis infection in cattle is now mostly confined to the respiratory system, which reflects transmission and establishment of infection mainly by this route. A single bacillus transported within a droplet nucleus is probably sufficient to establish infection within the bovine lung. Infected cattle should always be considered as potential sources of infection, since studies have demonstrated that a significant proportion of tuberculous cattle excrete M. bovis.In general, the dynamics of M. bovis transmission are poorly understood and the conditions under which a tuberculous animal becomes an effective disseminator of infection are currently not defined although environmental contamination appears to be a less effective method of disease transmission. Field studies indicate a wide spectrum of transmission rates but generally the spread of M. bovis infection is still considered to be a relatively slow process. Slaughter of diseased cattle detected by tuberculin testing and at meat plant inspection has been shown to be an effective policy for tuberculosis eradication, provided there are no other reservoirs of infection and all involved in the cattle industry are committed to a policy of eradication. Epidemiological approaches, particularly case-control studies, seem to provide the best method for quantifying the relative importance of the various sources of M. bovis transmission to cattle and modelling techniques can be used to assist in the design of cost-effective control measures that may lead to tuberculosis eradication.     

Pathologic findings and association of Mycobacterium bovis infection with the bovine NRAMP1 gene in cattle from herds with naturally occurring tuberculosis

OBJECTIVE: To determine necropsy and Mycobacterium bovis culture results in cattle from herds with tuberculosis, the role of the bovine NRAMP1 gene in resistance and susceptibility to infection with M bovis, and the association between magnitude of the tuberculous lesions and various types of M bovis isolates. ANIMALS: 61 cattle from herds with tuberculosis in Texas and Mexico. PROCEDURE: 61 cattle were evaluated by necropsy; 59 had positive and 2 had negative caudal fold tuberculin intradermal test (CFT) results. Thirty-three cattle with positive CFT results were genotyped to evaluate polymorphism of the 3' untranslated region of the bovine NRAMP1 gene, using single-stranded conformational analysis, 9 were resistant to M bovis with no tuberculous lesions and negative M bovis culture results, and 24 were susceptible with tuberculous lesions and positive M bovis culture results. Isolates of M bovis were analyzed by restriction fragment length polymorphism (RFLP) on the basis of IS6110 sequences and direct-repeat fingerprinting patterns. RESULTS: 21 (35.6%; 21/59) cattle with positive CFT results had tuberculous lesions or positive culture results; in addition, 1 of 2 cattle with negative CFT results had tuberculous lesions and positive culture results. Tuberculous lesions were most common in the thorax (35/63; 55.5%) and lymphoid tissues of the head (10/63; 15.9%). Tuberculous lesions varied from 1 to 11/animal; 8 of 21 (38.1%) had solitary lesions. Associations were not found between resistance or susceptibility to infection with M bovis and polymorphism in the NRAMP1 gene or between the magnitude of the lesions and various RFLP types of M bovis isolates. CONCLUSIONS AND CLINICAL RELEVANCE: The NRAMP1 gene does not determine resistance and susceptibility to infection with M bovis in cattle.     

Examination of the role of Mycoplasma bovis in bovine pneumonia and a mathematical model for its evaluation

The authors screened 34 large cattle herds for the presence of Mycoplasma bovis infection by examining slaughtered cattle for macroscopic lung lesions, by culturing M. bovis from lung lesions and at the same time by testing sera for the presence of antibodies against M. bovis. Among the 595 cattle examined, 33.9% had pneumonic lesions, mycoplasmas were isolated from 59.9% of pneumonic lung samples, and 10.9% of sera from those animals contained antibodies to M. bovis. In 25.2% of the cases M. bovis was isolated from lungs with no macroscopic lesions. The proportion of seropositive herds was 64.7%. The average seropositivity rate of individuals was 11.3% but in certain herds it exceeded 50%. A probability model was developed for examining the relationship among the occurrence of pneumonia, the isolation of M. bovis from the lungs and the presence of M. bovis specific antibodies in sera.