吉林省部分牛场BVDV、IBRV、BRSV的感染情况调查

为了解吉林省牛病毒性腹泻(BVD)、牛传染性鼻气管炎(IBR)、牛呼吸道合胞体病(BRS)的流行及其病原混合感染情况,在吉林省的9个地区随机采集了325份血清样品,采用ELISA血清抗体检测试剂盒与新型纳米PCR方法检测所采集样品。结果显示,ELISA检测BVDV抗体阳性243份,阳性率为74.77%,IBRV抗体阳性186份,阳性率为57.23%,BRSV抗体阳性90份,阳性率为27.69%,BVDV与IBRV混合感染率为31.69%;BVDV与BRSV混合感染率为9.54%,IBRV与BRSV混合感染率为1.54%,3种病毒混合感染率为17.23%。采用纳米PCR方法检测所有血清显示,BVDV抗原阳性42份,阳性率12.92%,未检出IBRV抗原阳性;BRSV抗原阳性29份,阳性率8.92%。BVDV与BRSV混合感染率为1.85%。     

新疆南疆地区某规模奶牛场牛病毒性腹泻抗原检测

为了解新疆南疆地区某规模化奶牛场牛病毒性腹泻病毒(bovine viral diarrheavirus,BVDV)感染情况,采用血清流行病学调查方法,对该规模化奶牛场2358份牛血清样品、35份新生犊牛耳组织样品进行BVDV抗原ELISA检测。结果显示,该场有9份血清样品为BVDV抗原阳性,阳性率为0.38%;对阳性样品的来源牛间隔21d后采血复检,检出1份阳性血清样品,确认该样品来源牛为持续性感染牛;在新生犊牛耳组织中,未检测出BVDV。本次抗原检测证明,新疆南疆地区规模化奶牛场存在一定的BVDV流行和持续感染,建议督促牛场积极开展BVDV净化工作。     

宁夏地区牛病毒性腹泻流行情况调研报告

牛病毒性腹泻/黏膜病（BVD）是由牛病毒性腹泻病毒（BVDV）引起的一种传染病。为调查宁夏地区BVD的流行情况,对制订防控措施提供数据支持,采集宁夏地区疑似感染BVDV且未进行疫苗免疫的1 500 头牛的血清进行抗体检测,对临床症状明显的295 头牛用肛拭子进行抗原检测。结果显示,牛病毒性腹泻抗体阳性率87.60%,抗原阳性率2.71%,存在较为严重的BVDV感染。     

牛病毒性腹泻的流行病学调查与防控

[目的]了解陕西省榆林市奶牛场牛病毒性腹泻病毒（BVDV）感染情况。[方法]从5家奶牛场采集156份血清样品,采用双抗体夹心ELISA方法进行BVDV抗原检测。[结果]除1家未检测到BVDV,其余4家均存在BVDV感染,BVDV抗原阳性率0～6.38%,平均为4.49%(7/156),成母牛、犊牛、育成牛BVDV抗原阳性率分别为5.66%、4.44%、3.45%。[结论]陕西省榆林市5家奶牛场存在一定的BVDV流行和持续性感染牛,且感染率较高,建议奶牛场采取定期检测、引种检疫、免疫接种等综合防控方法,以有效净化BVDV。     

牛病毒性腹泻病的危害及防控措施

正牛病毒性腹泻-黏膜病(BVD-MD)是由牛病毒性腹泻病毒(BVDV)引起的一种高度接触的传染性疾病。临床上以发热、腹泻和消化道黏膜坏死、糜烂或溃疡为特征,感染牛也可表现肺炎、流产、出血综合征、急性感染和持续性感染等多种临床症状。病毒引起的急性疾病称为牛病毒腹泻,引起的慢性持续感染称为黏膜病。发生该病后会导致产奶量下降、产肉率降低、繁殖障碍、生长迟缓等,给养牛业造成巨大经济损失。2014年,对我省3市8个养牛场(户)和1个屠宰场的检测结果发现,采样阳性率总体在20%~     

青海牦牛牛病毒性腹泻病毒的血清学调查

为掌握青海牦牛群中牛病毒性腹泻病毒(BVDV)的感染情况,采用ELISA试剂盒对采集于青海省6个规模牦牛饲养场和11户散养户的559份血清样品进行了BVDV抗体检测。检测结果显示,559份血清样品平均阳性率为36.14%,规模牦牛场平均阳性率为34.19%,散养户平均阳性率为39.42%。表明青海牦牛群中普遍存在BVDV感染,应该引起重视。     

牛病毒性腹泻病毒检测方法研究进展

牛病毒性腹泻病(bovine viral diarrhea, BVD)是由牛病毒性腹泻病毒(Bovine viral diarrhea virus, BVDV)感染导致的传染病。该病会导致牛生产性能下降,给全球养牛业带来严重的经济损失。BVD的临床表现和病理变化与其他牛源腹泻病毒病相似,因此有必要根据不同的条件选择快速高效的BVDV诊断方法,及时采取措施阻断BVDV在牛群间、BVDV持续感染牛(persistently infected, PI)与健康牛之间传播,减少BVDV对养牛业造成的经济损失。用于BVDV检测的方法很多,主要有病毒分离鉴定、荧光定量RT-PCR、RT-PCR、环介导等温扩增技术(LAMP)、重组酶聚合酶扩增技术(RPA)、胶体金免疫检测技术(GICT)、酶联免疫吸附试验(ELISA)、抗原捕获ELISA(AC-ELISA)、间接免疫荧光法(IFA)等。近年一些新兴技术和优化的方法被应用于BVDV的检测,如抗体液相芯片技术、CRISPR-LwCas13a系统、双重纳米RT-PCR法等,均具有特异性强和灵敏度高等优点。作者从抗原、抗体两个方面总结了BVDV检测方法的研...     

青海省黄南州牛群3种病毒性腹泻疾病的血清学调查

为了解青海省黄南州牛病毒性腹泻病毒(bovine viral diarrhea virus,BVDV)、牛轮状病毒(bovine rotavirus,BRV)和牛冠状病毒(bovine coronavirus,BCV)的流行与分布情况,采用ELISA方法分别对2010—2012年采自青海省黄南州规模化养殖场和散养户的842份血清样品进行了BVDV、BRV、BCV抗体检测。结果显示:BVDV、BRV、BCV平均抗体阳性率分别为21.14%,24.22%和27.20%。同时调查中发现,BVDV、BRV、BCV抗体阳性率及BVDV、BRV、BCV 2种及3种病原混合感染抗体阳性率在2010年至2012年均有逐步上升的趋势,表明我州牛群中BVDV、BRV、BCV的感染情况日益严重,混合感染现象日益突出,应引起重视,并建立行之有效的综合防控措施。     

甘肃省武威市肉牛牛病毒性腹泻的流行病学调查

试验旨在掌握武威市肉牛群牛病毒性腹泻病毒（BVDV）的感染及流行现状,为防控肉牛牛病毒性腹泻病（BVD/MD）提供依据。应用酶联免疫吸附试验和RT-PCR方法,对采集自武威市各县区的512份肉牛血样和425份具有腹泻症状肉牛的粪便进行BVDV抗体和BVDV病原检测。结果显示,所检血样BVDV抗体总阳性率为60.16%;成年母牛、青年牛、犊牛样品BVDV抗体阳性率分别为74.45%、68.35%、26.47%;来自规模场和散养户样品BVDV抗体阳性率分别为57.06%、55.47%;粪便样品BVDV病原总阳性率为7.76%。研究表明,武威市各县区的肉牛群普遍存在BVDV感染,应采取有效措施加强BVD/MD防控和净化工作。     

牛病毒性腹泻病毒、大肠杆菌和奇异变形杆菌混合感染致犊牛腹泻的研究

为确定甘肃省临夏州某奶牛场犊牛腹泻的病因,并提供合适的治疗方案和防控措施,试验采集该牛场13头腹泻犊牛的粪便和血清,通过胶体金技术、ELISA方法、细菌分离鉴定、Kirby-Bauer法分别进行病毒病原学检测、病毒血清学抗体检测、病原菌鉴定和药物敏感性试验。病毒学检测结果显示,13份粪样中未检测出牛轮状病毒（BRV）、牛冠状病毒（BCV）的抗原,牛病毒性腹泻病毒（BVDV）抗原阳性率为23.08%（3/13）;未检出BRV和BCV的抗体,BVDV血清学抗体阳性率为38.46%（5/13）。病原菌检测结果显示,13份粪便样品中,分离出13株大肠杆菌和7株奇异变形杆菌。药敏试验表明,分离的大肠杆菌和奇异变形杆菌对20种常规药物均产生了不同程度的耐药,且无对两种细菌均有效的药物。此次犊牛腹泻是由BVDV、大肠杆菌、奇异变形杆菌混合感染引起的,且大肠杆菌和奇异变形杆菌的耐药现象严重,本试验结果为该牛场进一步治疗此次的犊牛腹泻病提供了合理有效的依据。     

Evaluation of the effects of long-term storage of bovine ear notch samples on the ability of 2 diagnostic assays to identify calves persistently infected with bovine viral diarrhoea virus

Research aimed at optimising diagnostic laboratory procedures is central to the development of effective bovine viral diarrhoea virus (BVDV) control programmes. BVDV is a single-stranded RNA virus that crosses the placenta to infect foetuses, resulting in reproductive losses due to foetal death or persistently infected calves that die early in life. Persistently infected animals are widely accepted to be the primary reservoir of BVDV and the largest source of infection. This poses important challenges to overall animal/herd health and can cause major losses to the cattle industry. Long-term storage of bovine ear notch samples from calves persistently infected with BVDV may adversely affect the ability of diagnostic assays to detect the virus efficiently. In order to test this hypothesis, ear notch samples from 7 animals were divided into 2 groups. One set was subjected to prompt formalin fixation and the other set stored either as fresh samples without preservatives at -2 degrees C, or soaked overnight in phosphate buffered saline followed by freezing of the supernatant fluid at -2 degrees C. Frozen ear notches and ear notch supernatant yielded positive results with an antigen-capture, enzyme linked immunosorbent assay (AC-ELISA) for the duration of the study (6 months) and optical density (OD) values remained significantly within range. There was no significant difference between storing fresh ear notch samples or PBS at -2 degrees C. However, positive immunohistochemistry (IHC) staining on formalin fixed ear notches started to fade between Day 17 and Day 29 when stored at room temperature. It was concluded that fresh ear notches could safely be stored at -2 degrees C for a period of 6 months prior to testing for BVD viral antigens.     

Outbreak of Salmonella enterica serotype Newport in a beef cow-calf herd associated with exposure to bovine viral diarrhea virus

CASE DESCRIPTION: Severe disease and death in cows and calves affected 1 of 3 separate groups (A, B, and C) of cattle on a commercial cow-calf operation. CLINICAL FINDINGS: Clinical illness consisting of severe watery and bloody diarrhea, dehydration, weakness, and death affected adult cows and calves in 1 group (group B). Salmonella enterica serotype Newport was recovered from tissues of cows and calves from group B. TREATMENT AND OUTCOME: Despite supportive and antimicrobial treatment of cattle in group B, cow mortality rate attributable to salmonellosis in that group was 7.9% (32/407); calf mortality rate was 14.4% (52/361). None of the cows in Groups A or C died, and the calf mortality rate in those groups was low. Salmonella enterica serotype Newport was recovered from pooled fecal samples subsequently collected from each group of cows. Bovine viral diarrhea virus (BVDV) antigen was identified in an ear notch sample collected from a necropsied calf from group B. Subsequently, ear notch specimens from cattle in all 3 groups were tested for BVDV antigen. A significantly higher proportion of calves persistently infected with BVDV was identified in group B (8/295 [2.7%]), compared with the proportion in groups A and C combined (1/287 [0.3%]). CLINICAL RELEVANCE: Outbreaks of disease attributable to Salmonella Newport infection in beef cattle are unusual. Because of the immunosuppressive nature of BVDV, the possibility of animals persistently infected with BVDV within the herd should be considered during investigation of unusual outbreaks of infectious diseases.     

Prevalence and characterization of bovine viral diarrhea virus in the white-tailed deer population in Indiana.

Bovine viral diarrhea (BVD) is one of the economically important diseases of cattle. For many years, different types of vaccines have been commercially available, yet this disease is hard to control in high-density population areas. Detection and isolation of bovine viral diarrhea virus (BVDV) from any potential reservoir is vital, especially when considering virus eradication from a herd or locale. One potential source is wild ruminants. Ear notches and lymph nodes were collected from the wild population of white-tailed deer (Odocoileus virginianus) during deer hunting season in Indiana and tested for BVDV with a commercial BVD antigen capture enzyme-linked immunosorbent assay. Two samples out of 745 collected samples were positive, and subsequently cp and ncp BVDV was isolated from 1 ear notch and 1 lymph node. These isolates were genotyped as type 1a and 1b based on sequence analysis of the 5' untranslated region (UTR). The results of the present study indicate that the prevalence of BVDV in the white-tailed deer population of Indiana is about 0.3%. Wild ruminants infected with BVDV should be taken into consideration during an eradication program of BVDV from the livestock population.     

Challenge with Bovine viral diarrhea virus by exposure to persistently infected calves: protection by vaccination and negative results of antigen testing in nonvaccinated acutely infected calves

Calves persistently infected (PI) with Bovine viral diarrhea virus (BVDV) represent an important source of infection for susceptible cattle. We evaluated vaccine efficacy using calves PI with noncytopathic BVDV2a for the challenge and compared tests to detect BVDV in acutely or transiently infected calves versus PI calves. Vaccination with 2 doses of modified live virus vaccine containing BVDV1a and BVDV2a protected the calves exposed to the PI calves: neither viremia nor nasal shedding occurred. An immunohistochemistry test on formalin-fixed ear notches and an antigen-capture enzyme-linked immunosorbent assay on fresh notches in phosphate-buffered saline did not detect BVDV antigen in any of the acutely or transiently infected calves, whereas both tests had positive results in all the PI calves.     

Implementation of immunohistochemistry on frozen ear notch tissue samples in diagnosis of bovine viral diarrhea virus in persistently infected cattle

Background

Bovine viral diarrhea is a contagious disease of domestic and wild ruminants and one of the most economically important diseases in cattle. Bovine viral diarrhea virus belongs to the genus Pestivirus, within the family Flaviviridae. The identification and elimination of the persistently infected animals from herds is the initial step in the control and eradication programs. It is therefore necessary to have reliable methods for diagnosis of bovine viral diarrhea virus. One of those methods is immunohistochemistry. Immunohistochemistry on formalin fixed, paraffin embedded tissue is a routine technique in diagnosis of persistently infected cattle from ear notch tissue samples. However, such technique is inappropriate due to complicated tissue fixation process and it requires more days for preparation. On the contrary, immunohistochemistry on frozen tissue was usually applied on organs from dead animals. In this paper, for the first time, the imunohistochemistry on frozen ear notch tissue samples was described.

Findings

Seventeen ear notch tissue samples were obtained during the period 2008-2009 from persistently infected cattle. Samples were fixed in liquid nitrogen and stored on -20°C until testing. Ear notch tissue samples from all persistently infected cattle showed positive results with good section quality and possibility to determinate type of infected cells.

Conclusions

Although the number of samples was limited, this study indicated that immunohistochemistry on formalin fixed paraffin embedded tissue can be successfully replaced with immunohistochemistry on frozen ear notch tissue samples in diagnosis of persistently infected cattle.     

Detection of Bovine Viral Diarrhoea Virus Infected Cattle – Testing Tissue Samples Derived from Ear Tagging Using an Erns Capture ELISA

A new diagnostic approach testing tissue samples derived from cattle ear tagging for bovine viral diarrhoea virus (BVDV) antigen in a commercially available antigen capture enzyme‐linked immunosorbent assay (ACE) was developed. To validate this method, 99 positive and 469 negative samples were tested. With those samples the assay yielded a sensitivity of 100% and specificity of ≥99.6%. Serum and ear tissue samples from 11 persistently infected (PI) BVDV calves were tested. While serum samples were negative after intake of colostrum, the ear tissue samples could be detected positive for BVDV all the time. Testing multiple samples derived from the same ear from PI cattle yielded positive results and low variation. Using cattle ear tags combining the ear tag application with sampling of a small ear tissue plug and testing those tissue samples with an ACE could be a reliable and economic way of BVDV testing.     

Detection of bovine viral diarrhoea virus infected cattle--testing tissue samples derived from ear tagging using an Erns capture ELISA

A new diagnostic approach testing tissue samples derived from cattle ear tagging for bovine viral diarrhoea virus (BVDV) antigen in a commercially available antigen capture enzyme-linked immunosorbent assay (ACE) was developed. To validate this method, 99 positive and 469 negative samples were tested. With those samples the assay yielded a sensitivity of 100% and specificity of >or=99.6%. Serum and ear tissue samples from 11 persistently infected (PI) BVDV calves were tested. While serum samples were negative after intake of colostrum, the ear tissue samples could be detected positive for BVDV all the time. Testing multiple samples derived from the same ear from PI cattle yielded positive results and low variation. Using cattle ear tags combining the ear tag application with sampling of a small ear tissue plug and testing those tissue samples with an ACE could be a reliable and economic way of BVDV testing.     

Evaluation of two commercial enzyme-linked immunosorbent assays for detection of bovine viral diarrhoea virus in serum and skin biopsies of cattle

AIM: To assess the ability of two commercial bovine viral diarrhoea (BVD) virus (BVDV) antigen-capture enzyme-linked immunosorbent assays (ELISAs) to detect virus in serum and skin biopsies. METHODS: Thirty cattle persistently infected (PI) with BVDV were identified using routine diagnostic laboratory testing. Additional ear-notch skin biopsies and blood samples were collected from these animals to confirm the diagnosis, and from 246 cohorts, to determine their BVDV status. Skin biopsies were soaked overnight in buffer and the eluate collected. All sera and eluate were tested using two commercially available ELISAs for detecting BVDV antigen, and a subsample of positive and negative sera was tested using a polymerase chain reaction (PCR) test. A study was also performed to ascertain the risk of cross contamination occurring during the collection and processing of skin biopsies. RESULTS: Both serum and skin samples tested using either ELISA resulted in the detection of all cattle identified as PI and no non-infected cattle were incorrectly classified as infected using either method. Agreement between all assays (ELISAs, whether performed on serum or skin, and PCR) was 100%. No cross-contamination of skin samples between animals was evident using routine biopsy methods. CONCLUSIONS: Viraemic cattle infected with BVDV were accurately identified using either of the two commercial ELISAs evaluated on either serum or skin samples. CLINICAL RELEVANCE: Either skin biopsies or serum samples can be collected from cattle to determine their BVDV status. This should overcome problems in accurately identifying the infection status of young calves in which colostral antibodies might interfere with the antigen-capture ELISA.     

Immunohistochemistry used as a screening method for persistent bovine viral diarrhea virus infection.

Cattle persistently infected (PI) with bovine viral diarrhea virus(BVDV) are a major source of infection to herds. To successfully control BVDV, it is necessary to identify and cull those cattle PI with BVDV. Immunohistochemistry (IHC) is a useful tool for sensitive and specific detection of BVDV antigens in infected cattle.Skin of cattle PI with BVDV is one of the tissues where BVDV can be consistently identified by IHC and is readily accessible for sampling. Use of IHC on skin biopsies (in the form of ear notches)as a method to identify cattle PI with BVDV has resulted in a reliable, affordable technique for mass testing of cattle at an early age without maternal antibody interference. The ability to test large numbers of cattle to identify those Pl with BVDV will enable implementation of programs for control and eventual eradication of BVDV.