Bovine viral diarrhea virus (BVDV) causes significant economic loss in cattle. Detection of persistently infected (PI) animals is an important control measure, but persistence of maternal antibodies may result in false-negative test results. We assessed the sensitivity and specificity of 2 antigen ELISAs (Idexx BVDV Ag/Serum Plus and BVDV PI X2) and a reverse-transcription real-time PCR (RT-rtPCR; Idexx RealPCR BVDV) assay for detecting PI calves. Ear notch samples were collected from 1,030 calves ~3, 10, 24, and 38 d old (days 3, 10, 24, and 38). All day 38 samples were tested using 2 antigen ELISAs and RT-rtPCR, and any calf that tested positive by any of these tests was blood sampled at ~100 d old (day 100) for antigen and antibody testing by ELISA; samples collected on days 3, 10, and 24 were tested using the antigen ELISAs and PCR. Calves were defined as PI if they were test-positive on day 38 by either ELISA or PCR and were antigen-positive on day 100. Twenty-six calves were PCR BVDV test–positive and one was BVDV PI X2 ELISA–positive at day 38. Five calves were defined as PI, and all tested positive by ELISAs and RT-PCR assay on days 3, 10, and 24. The sensitivity and specificity were 100% for both antigen ELISAs and 96.7% and 100%, respectively, by RT-rtPCR. Test results were not affected by calf age, suggesting that testing for PI calves can be undertaken at any age.

牛病毒性腹泻病毒 (BVDV) 对牛造成重大经济损失。检测持续感染 (PI) 动物是一项重要的控制措施，但母体抗体的持续存在可能导致假阴性检测结果。我们评估了 2 种抗原 ELISA（Idexx BVDV Ag/Serum Plus 和 BVDV PI X2）和逆转录实时 PCR（RT-rtPCR；Idexx RealPCR BVDV）检测用于检测 PI 小牛的敏感性和特异性。从大约 3、10、24 和 38 天（第 3、10、24 和 38 天）的 1,030 只小牛身上采集耳刻痕样本。使用 2 种抗原 ELISA 和 RT-rtPCR 对所有 38 天的样本进行了测试，通过这些测试中的任何一种测试呈阳性的任何小牛都在约 100 天（第 100 天）时采集血液样本，以通过 ELISA 进行抗原和抗体测试；在第 3、10 和 24 天收集的样本使用抗原 ELISA 和 PCR 进行了测试。如果犊牛在第 38 天通过 ELISA 或 PCR 检测呈阳性，并且在第 100 天呈抗原阳性，则定义为 PI。26 头犊牛在第 38 天 PCR BVDV 检测呈阳性，1 头 BVDV PI X2 ELISA 呈阳性. 5 头小牛被定义为 PI，在第 3、10 和 24 天通过 ELISA 和 RT-PCR 检测均呈阳性。抗原 ELISA 的敏感性和特异性均为 100%，RT 分别为 96.7% 和 100% -rtPCR。测试结果不受小牛年龄的影响，这表明可以在任何年龄对 PI 小牛进行测试。和 24. 两种抗原 ELISA 的敏感性和特异性均为 100%，RT-rtPCR 的敏感性和特异性分别为 96.7% 和 100%。测试结果不受小牛年龄的影响，这表明可以在任何年龄对 PI 小牛进行测试。和 24. 两种抗原 ELISA 的敏感性和特异性均为 100%，RT-rtPCR 的敏感性和特异性分别为 96.7% 和 100%。测试结果不受小牛年龄的影响，这表明可以在任何年龄对 PI 小牛进行测试。