Evaluation of diagnostic tests used for detection of bovine viral diarrhea virus and prevalence of subtypes 1a, 1b, and 2a in persistently infected cattle entering a feedlot
Evaluation of diagnostic tests used for detection of bovine viral diarrhea virus and prevalence of subtypes 1a, 1b, and 2a in persistently infected cattle entering a feedlot
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DOI：
10.2460/javma.228.4.578
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发表时间：
2006-02-15
影响因子：
1.9
通讯作者：
Funk, RA
中科院分区：
文献类型：
--
作者：
Fulton, RW;Hessman, B;Funk, RA
目的-评价用于检测牛病毒性腹泻病毒（BVDV）的诊断试验，并确定BVDV亚型1a、1b和2a在进入饲养场的持续感染（PI）牛中的流行率。设计-前瞻性研究。动物——21,743头小牛。程序-通过抗原捕获ELISA （ACE）在新鲜皮肤（耳沟）标本上进行初步检测呈阳性，从小牛身上获得样品，并重复ACE。此外，将皮肤标本固定在10%福尔马林中性缓冲液中进行免疫组织化学（IHC）检测，并对血清样本进行逆转录酶PCR （RT-PCR）检测和病毒分离。通过对病毒基因组的5'非翻译区进行测序，确定了病毒亚型。结果- 88头小牛的初始ACE结果为BVDV阳性。经后续检测，88头小牛中86头的ACE、免疫组化、RT-PCR和病毒分离检测结果均为阳性；2头小牛的所有后续检测结果均为阴性。这两头小牛的检测结果呈假阳性。根据IHC结果，21,743头小牛中有86头为PI合并BVDV，患病率为0.4%。BVDV亚型分布为BVDV1b（77.9%）、BVDV1a（11.6%）和BVDV2a（10.5%）。结论和临床意义——诸如ACE之类的快速测试允许在进一步测试结果出来之前对PI牛进行识别和分离，从而减少它们与饲养场其他牛群的接触。虽然给进入饲养场的牛接种了含有BVDV1a和2a成分的疫苗，但这些疫苗可能不能提供足够的BVDV1b保护。
Objective - To evaluate diagnostic tests used for detection of bovine viral diarrhea virus (BVDV) and determine the prevalence of BVDV subtypes 1 a, 1 b, and 2a in persistently infected (PI) cattle entering a feedlot.Design - Prospective study.Animals - 21,743 calves.Procedures - Samples were obtained from calves initially testing positive via antigen capture ELISA (ACE) performed on fresh skin (ear notch) specimens, and ACE was repeated. Additionally, immunohistochemistry (IHC) was performed on skin specimens fixed in neutral-buffered 10% formalin, and reverse transcriptase PCR (RT-PCR) assay and virus isolation were performed on serum samples. Virus was subtyped via sequencing of the 5' untranslated region of the viral genome.Results - Initial ACE results were positive for BVDV in 88 calves. After subsequent testing, results of ACE, IHC, RT-PCR assay, and viral isolation were positive in 86 of 88 calves; results of all subsequent tests were negative in 2 calves. Those 2 calves had false-positive test results. On the basis of IHC results, 86 of 21,743 calves were PI with BVDV, resulting in a prevalence of 0.4%. Distribution of BVDV subtypes was BVDV1b (77.9%), BVDV1a (11.6%), and BVDV2a (10.5%).Conclusions and Clinical Relevance - Rapid tests such as ACE permit identification and segregation of PI cattle pending results of further tests, thus reducing their contact with the rest of the feedlot population. Although vaccines with BVDV1a and 2a components are given to cattle entering feedlots, these vaccines may not provide adequate protection against BVDV1b.