Muasya Daniel, Leeuwen John Van, Gitau George, McKenna Shawn, Heider Luke, Muraya Joan
Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island (UPEI), Charlottetown, Prince Edward Island, Canada.
Department of Clinical Studies, Faculty of Veterinary Medicine, University of Nairobi, Nairobi, Kenya.
Vet World. 2022 May;15(5):1290-1296. doi: 10.14202/vetworld.2022.1290-1296. Epub 2022 May 24.
Bovine viral diarrhea virus (BVDV) and classical swine fever virus (CSFV) are important pathogens of cattle and pigs, respectively, and belong to the genus Pestivirus. As CSFV has been shown to infect cattle, it can create diagnostic challenges of BVDV results through possible cross-reactivity where cattle could be exposed to pigs and CSFV. This study aimed to determine the possible cross-reactivity of BVDV and CSFV enzyme-linked immunosorbent assay (ELISA) results for antigen (Ag) and antibody (Ab) among smallholder dairy cattle in Kenya.
This was a cross-sectional study based on a single visit to farms to collect serum samples and other descriptive farm-level and animal-level information. Testing for BVDV Ag and Ab was conducted on serum samples from 320 dairy cows and heifers, with CSFV Ag and Ab testing conducted on a subset of 133 and 74 serum samples, respectively. CSFV testing was based on BVDV test results and the availability of enough sample volume from farms that kept pigs. The Ag and Ab tests utilized IDEXX ELISA for both BVDV and CSFV.
For the 74 samples with Ab tests for both viruses, 40 (54.0%) were BVDV Ab positive, while 63 (85.1%) were CSFV Ab positive. Of the 40 BVDV Ab positive samples, 36 cattle (90.0%) tested positive for CSFV Ab. However, of the 34 BVDV Ab negative samples, 27 (79.4%) were CSFV Ab test-positive. For the 133 samples with Ag tests for both viruses, 125 (94.0%) were BVDV Ag positive, while 2 (1.5%) samples were CSFV Ag positive. None of the eight BVDV Ag negative samples was positive for CSFV Ag and only two (1.6%) of the 125 BVDV Ag positive samples were positive for CSFV Ag.
The results indicate either substantial cross-reactivity of the two Ab ELISA tests, or reactivity with some other protein in the samples that led to the positive Ab test results. There was only limited evidence for cross-reactivity of the two Ag ELISA tests. We recommend that Pestivirus genus cross-reactivity be considered when interpreting BVDV ELISA results in cattle, more for Ab than Ag tests. Further research is needed to clarify the levels of cross-reactivity between BVDV and other Pestivirus Ag and Ab tests from animals on mixed-species farms.
牛病毒性腹泻病毒（BVDV）和猪瘟病毒（CSFV）分别是牛和猪的重要病原体，均属于瘟病毒属。由于已证实CSFV可感染牛，在牛可能接触猪和CSFV的情况下，可能会因交叉反应给BVDV检测结果带来诊断挑战。本研究旨在确定肯尼亚小农户奶牛群中BVDV和CSFV酶联免疫吸附测定（ELISA）对抗原（Ag）和抗体（Ab）检测结果的可能交叉反应性。
这是一项横断面研究，单次走访农场收集血清样本以及其他农场层面和动物层面的描述性信息。对320头奶牛和小母牛的血清样本进行BVDV Ag和Ab检测，分别对133份和74份血清样本子集进行CSFV Ag和Ab检测。CSFV检测基于BVDV检测结果以及养猪农场是否有足够的样本量。Ag和Ab检测均采用IDEXX ELISA检测BVDV和CSFV。
在对两种病毒进行Ab检测的74份样本中，40份（54.0%）BVDV Ab呈阳性，63份（85.1%）CSFV Ab呈阳性。在40份BVDV Ab阳性样本中，36头牛（90.0%）CSFV Ab检测呈阳性。然而，在34份BVDV Ab阴性样本中，27份（79.4%）CSFV Ab检测呈阳性。在对两种病毒进行Ag检测的133份样本中，125份（94.0%）BVDV Ag呈阳性，2份（1.5%）样本CSFV Ag呈阳性。8份BVDV Ag阴性样本中没有一份CSFV Ag呈阳性，在125份BVDV Ag阳性样本中只有两份（1.6%）CSFV Ag呈阳性。
结果表明两种Ab ELISA检测存在显著交叉反应，或者样本中与其他某种蛋白质发生反应导致Ab检测结果呈阳性。两种Ag ELISA检测仅存在有限的交叉反应证据。我们建议在解读牛的BVDV ELISA结果时考虑瘟病毒属交叉反应性，对于Ab检测比对Ag检测更应如此。需要进一步研究以阐明BVDV与混养农场动物的其他瘟病毒Ag和Ab检测之间的交叉反应水平。
