Lanyon S R, McCoy R, Bergman E, Reichel M P
School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy, South Australia, 5371, Australia.
Aust Vet J. 2014 Jul;92(7):269-73. doi: 10.1111/avj.12188.
The aims of this study were to evaluate a commercially available ELISA for the detection of bovine viral diarrhoea virus (BVDV)-specific antibodies in individual milk compared with individual serum samples, and in bulk milk samples compared with within-herd antibody prevalence and bulk milk quantitative reverse transcription polymerase chain reaction (qRT-PCR) results.
Paired individual serum and individual milk samples were collected from 125 lactating cows and tested by ELISA; 96 bulk milk samples were also tested. Within-herd antibody prevalence was calculated based on milk ELISA results for 25 individual cows in each herd. Additionally, 167 bulk milk samples were tested for BVDV-specific antibodies by ELISA and for the presence of BVDV by qRT-PCR to establish the correlation between antibody result and virus presence.
Good agreement was observed between individual milk and serum results (Kappa = 0.865). The ELISA was observed to detect BVDV-specific antibodies in individual milk samples with a relative sensitivity of 96.6% and specificity of 89.2%. The bulk milk samples revealed a strong (r(2) = 0.95) relationship between the ELISA result and the within-herd antibody prevalence. The proportion of herds that tested positive by bulk milk qRT-PCR increased as the bulk milk antibody S/P ratio increased.
Commercially available ELISA testing of individual and bulk milk samples is an appropriate alternative to serum testing with good test performance in these samples. Determining a threshold for the detection of herds containing active BVD infection by testing bulk milk is a novel use for an antibody ELISA kit and provides more practical, relevant test results.
本研究旨在评估一种市售酶联免疫吸附测定（ELISA）法，用于检测个体牛奶中牛病毒性腹泻病毒（BVDV）特异性抗体，并与个体血清样本进行比较；同时检测批量牛奶样本中的该抗体，并与牛群内抗体流行率及批量牛奶定量逆转录聚合酶链反应（qRT-PCR）结果进行比较。
从125头泌乳奶牛中采集配对的个体血清和个体牛奶样本，并用ELISA法进行检测；还对96份批量牛奶样本进行了检测。根据每个牛群中25头个体奶牛的牛奶ELISA检测结果计算牛群内抗体流行率。此外，对167份批量牛奶样本进行ELISA检测以确定BVDV特异性抗体，并通过qRT-PCR检测BVDV的存在情况，以建立抗体检测结果与病毒存在情况之间的相关性。
个体牛奶和血清检测结果之间具有良好的一致性（Kappa = 0.865）。观察发现ELISA法检测个体牛奶样本中BVDV特异性抗体的相对灵敏度为96.6%，特异性为89.2%。批量牛奶样本的ELISA检测结果与牛群内抗体流行率之间呈现出强相关性（r² = 0.95）。随着批量牛奶抗体S/P比值的增加，通过批量牛奶qRT-PCR检测呈阳性的牛群比例也随之增加。
对个体和批量牛奶样本进行市售ELISA检测是血清检测的合适替代方法，在这些样本中具有良好的检测性能。通过检测批量牛奶来确定检测含有活跃BVD感染牛群的阈值，是抗体ELISA试剂盒的一种新用途，可提供更实际、相关的检测结果。
