Viral Infectious Diseases Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
BMC Vet Res. 2012 Sep 21;8:167. doi: 10.1186/1746-6148-8-167.
Bovine leukemia virus (BLV) is associated with enzootic bovine leukosis, which is the most common neoplastic disease of cattle. BLV infects cattle worldwide, imposing a severe economic impact on the dairy cattle industry. Recently, we developed a new quantitative real-time polymerase chain reaction (PCR) method using Coordination of Common Motifs (CoCoMo) primers to measure the proviral load of known and novel BLV variants in BLV-infected animals. Indeed, the assay was highly effective in detecting BLV in cattle from a range of international locations. This assay enabled us to demonstrate that proviral load correlates not only with BLV infection capacity as assessed by syncytium formation, but also with BLV disease progression. In this study, we compared the sensitivity of our BLV-CoCoMo-qPCR method for detecting BLV proviruses with the sensitivities of two real-time PCR systems, and also determined the differences of proviral load with serotests.
BLV-CoCoMo-qPCR was found to be highly sensitive when compared with the real-time PCR-based TaqMan MGB assay developed by Lew et al. and the commercial TaKaRa cycleave PCR system. The BLV copy number determined by BLV-CoCoMo-qPCR was only partially correlated with the positive rate for anti-BLV antibody as determined by the enzyme-linked immunosorbent assay, passive hemagglutination reaction, or agar gel immunodiffusion. This result indicates that, although serotests are widely used for the diagnosis of BLV infection, it is difficult to detect BLV infection with confidence by using serological tests alone. Two cattle were experimentally infected with BLV. The kinetics of the provirus did not precisely correlate with the change in anti-BLV antibody production. Moreover, both reactions were different in cattle that carried different bovine leukocyte antigen (BoLA)-DRB3 genotypes.
Our results suggest that the quantitative measurement of proviral load by BLV-CoCoMo-qPCR is useful tool for evaluating the progression of BLV-induced disease. BLV-CoCoMo-qPCR allows us to monitor the spread of BLV infection in different viewpoint compared with classical serotest.
牛白血病病毒（BLV）与地方性牛白血病有关，这是牛最常见的肿瘤疾病。BLV 感染全世界的牛，给奶牛养殖业造成严重的经济影响。最近，我们使用协调共同基序（CoCoMo）引物开发了一种新的定量实时聚合酶链反应（PCR）方法，用于测量 BLV 感染动物中已知和新型 BLV 变体的前病毒载量。事实上，该检测方法在检测来自不同国家和地区的牛 BLV 方面非常有效。该检测方法使我们能够证明前病毒载量不仅与通过合胞体形成评估的 BLV 感染能力相关，而且与 BLV 疾病进展相关。在这项研究中，我们比较了我们的 BLV-CoCoMo-qPCR 方法检测 BLV 前病毒的敏感性与两种实时 PCR 系统的敏感性，并确定了与血清学检测的前病毒载量差异。
与 Lew 等人开发的基于 TaqMan MGB 的实时 PCR 检测系统和商业 TaKaRa cycleave PCR 系统相比，BLV-CoCoMo-qPCR 被发现具有高度的敏感性。BLV-CoCoMo-qPCR 确定的 BLV 拷贝数与酶联免疫吸附试验、被动血凝反应或琼脂凝胶免疫扩散测定的抗 BLV 抗体阳性率仅部分相关。这一结果表明，尽管血清学检测广泛用于 BLV 感染的诊断，但仅通过血清学检测很难有信心地检测 BLV 感染。两头牛被实验性感染 BLV。前病毒的动力学与抗 BLV 抗体产生的变化并不完全相关。此外，在携带不同牛白细胞抗原（BoLA）-DRB3 基因型的牛中，两种反应都不同。
我们的结果表明，通过 BLV-CoCoMo-qPCR 定量测量前病毒载量是评估 BLV 诱导疾病进展的有用工具。BLV-CoCoMo-qPCR 使我们能够从不同的角度监测 BLV 感染的传播，与经典的血清学检测相比。
