Bovine leukemia virus (BLV) is widely prevalent in Japanese dairy farms. To control BLV infections in Japan, segregating or managing cows according to their proviral load (PVL) is a rational strategy. This study was conducted to establish a quantitative procedure for estimating blood PVL per microliter using a statistical model to offer a cost-effective alternative to the conventional quantitative real-time PCR method. In total, 250 Holstein cows infected with BLV were identified from 10 commercial dairy farms. Information on age was collected and blood samples were tested for white blood cell and lymphocyte counts and PVL using PCR. Generalized linear models with quasi-Poisson errors were used to estimate PVL by selecting age, logarithm of lymphocyte count, and their interaction term as explanatory variables. To evaluate the model, blood samples of 92 BLV-infected Holstein cows from 2 other commercial dairy farms were tested, and measured PVL values were compared with estimated PVL values by the model. The logPVL per microliter was modeled by positive associations with log lymphocyte count and age and a negative association with the interaction term. In the evaluation, measured PVL values had a strong correlation with estimated PVL values (Spearman's ρ = 0.87). In conclusion, our model provides a cost-effective and more rapid alternative to the conventional method to facilitate test and segregation or management of BLV-suspected cows.

牛白血病病毒（BLV）在日本奶牛场中广泛流行。为了控制日本的BLV感染，根据母牛的前病毒负荷（PVL）隔离或管理母牛是一种合理的策略。进行了这项研究，以建立使用统计模型估算每微升血液PVL的定量程序，从而为传统的定量实时PCR方法提供了一种经济高效的替代方法。从10个商业奶牛场中总共鉴定出250头感染了BLV的荷斯坦奶牛。收集年龄信息，并使用PCR检测血液样本中的白细胞和淋巴细胞计数以及PVL。通过选择年龄，淋巴细胞计数的对数及其相互作用项作为解释变量，使用具有准泊松误差的广义线性模型估算PVL。要评估模型，测试了来自其他2个商业奶牛场的92例受BLV感染的荷斯坦奶牛的血液样本，并通过模型将测得的PVL值与估计的PVL值进行了比较。通过与log淋巴细胞计数和年龄呈正相关而与相互作用项呈负相关来对每微升logPVL进行建模。在评估中，测得的PVL值与估计的PVL值具有很强的相关性（Spearman'sρ = 0.87）。总之，我们的模型为常规方法提供了一种经济高效且更快速的替代方法，以方便对BLV怀疑的母牛进行测试，隔离或管理。