Bovine Leukemia Virus: A novel Zoonosis?

牛白血病病毒（BLV）与人t细胞白血病病毒（HTLV）密切相关，大量牛已被证明感染该病毒；因此，弄清人类是否也能感染这种病毒是至关重要的。(1) BLV原病毒DNA （pDNA）的检测方法：采用PCR方法从外周血单核细胞（PBMC） DNA中扩增出BLV pDNA，并采用Southern blotting （SB）法进行鉴定，或采用实时荧光定量PCR法进行定量。虽然在一些样本中几乎检测不到BLV pDNA，但验证实验的结果不一致。考虑到前病毒载量可能在阈值水平附近，我们通过用eb病毒（Epstein-Barr virus， EBV）转化外周血B细胞来扩增被认为是blv靶向细胞的B细胞。利用来自健康志愿者的大量ebv转化的B细胞DNA样本，我们可以扩增和测序几种BLV基因，如tax， env和pol。BLV env基因的系统发育分析表明，More鉴定的BLV pDNA与美国和澳大利亚的BLV pDNA接近，与日本奶牛的BLV pDNA几乎相同。然而，迄今为止，BLV pDNA的更多延伸区域的扩增尚未成功，部分原因是PCR困难和拷贝数低。(2)抗blv抗体的检测从blv持续感染细胞的裂解液或从这些细胞的无细胞培养上清液中制备blv蛋白。此外，从大肠杆菌培养物中纯化重组BLV Tax或Env蛋白作为GST融合蛋白。这些BLV蛋白作为抗原用于Western blotting （WB）检测人血清样品中的BLV抗体。根据HTLV WB的诊断标准，11名健康志愿者中1人（9%）阳性，1人（9%）不明确，32名乳腺癌患者中1人（3%）阳性，3人（9%）不明确。然而，在BLV血清阳性个体中，BLV pDNA的存在尚未得到证实。讨论：与美国最近报道的一项研究不同，没有很多BLV血清阳性个体，抗BLV抗体的存在并不能预测其外周血B细胞中BLV pDNA的存在。因此，BLV感染在人类中可能是罕见的，如果有的话。少

Bovine leukemia virus (BLV) is closely related to human T-cell leukemia virus (HTLV), and considerable number of cattle have been shown to be infected with this virus; therefore, it is critical to clarify if human being can also be infected with this virus.(1) Detection of BLV provirus DNA (pDNA)BLV pDNA was amplified from peripheral blood mononuclear cells (PBMC) DNA with PCR and confirmed with Southern blotting (SB), or quantitated with real-time PCR. Although barely detectable BLV pDNA was found in a few samples, results of confirmatory experiments were inconsistent. Considering that proviral load might be around threshold level, we expanded peripheral blood B cells that are supposed to be BLV-targeting cells by transforming them with Epstein-Barr virus (EBV). Using large amount of DNA samples of EBV-transformed B cells derived from a healthy volunteer, we could amplified and sequenced several BLV genes such as tax, env and pol. Phylogenetic analysis of BLV env gene demonstrated the … More identified BLV pDNA was close to those in the USA and Australia and almost identical to those found in cows in Japan. However, amplification of more extended regions of BLV pDNA has been unsuccessful so far, partly because of difficulty in PCR and low copy number.(2) Detection of anti-BLV antibodyBLV proteins were prepared from lysates of persistently BLV-infected cells or from cell-free culture supernatants of those cells. In addition, recombinant BLV Tax or Env protein was purified as fusion proteins with GST from E. coli cultures. Those BLV proteins were used as antigens for Western blotting (WB) to detect anti-BLV antibodies in human serum samples. Based on the diagnostic criteria for HTLV WB, one (9%) was positive and another (9%) was ambiguous among 11 healthy volunteers, and one (3%) was positive and three (9%) were ambiguous among 32 patients with breast cancer. However, the presence of BLV pDNA was not confirmed in BLV-seropositive individuals.Discussion: Different from a recently reported study in the USA, there were not many BLV-seropositive individuals and the presence of anti-BLV antibody did not predict the presence of BLV pDNA in their peripheral blood B cells. Thus, BLV infection is probably rare, if any, in humans. Less