Taylor J A, Jacobs R M
Department of Pathology, University of Guelph, Ontario.
Lab Invest. 1993 Sep;69(3):340-6.
Bovine leukemia virus (BLV) is difficult to detect in freshly isolated peripheral blood mononuclear cells (PBMCs) from infected cattle. The lack of viral expression has been attributed to a plasma blocking factor capable of inhibiting the in vitro expression of the BLV p24 antigen.
The purpose of this study was to investigate the effects of plasma and serum on the in vitro synthesis of the p24 antigen within short-term cultures of PBMCs from BLV-seropositive cows. BLV p24 antigen was detected in the cell lysate using an antigen capture enzyme-linked immunosorbent assay.
Antigen synthesis was suppressed in PBMCs cultured in plasma from both seropositive and seronegative cows. Serum from infected cows suppressed p24 expression, but to a lesser extent than any of the plasmas. Addition of phytohemagglutinin-P to the cultures resulted in the detection of more p24 in PBMCs cultured in serum, but had no effect on p24 expression within cells cultured in plasma. The reduction in p24 was not related to lower cell viability, nor was it influenced by the effects of the anticoagulant citrate-phosphate dextrose on calcium-dependent lymphocyte activation. No significant difference was observed in the potency of the p24 inhibition between cells grown in autologous and homologous serum, or between cells grown in autologous and homologous plasma from seropositive cows.
Blocking activity is present in the plasma of seronegative cows, and in the plasma and serum of BLV-seropositive cows. This activity may be important in regulating viral latency and provirus expression in vivo.
牛白血病病毒（BLV）很难在从感染牛新鲜分离的外周血单个核细胞（PBMC）中检测到。病毒表达的缺乏归因于一种能够抑制BLV p24抗原体外表达的血浆阻断因子。
本研究的目的是调查血浆和血清对来自BLV血清阳性奶牛的PBMC短期培养物中p24抗原体外合成的影响。使用抗原捕获酶联免疫吸附测定法在细胞裂解物中检测BLV p24抗原。
在来自血清阳性和血清阴性奶牛的血浆中培养的PBMC中，抗原合成受到抑制。感染奶牛的血清抑制p24表达，但程度低于任何一种血浆。向培养物中添加植物血凝素-P可导致在血清中培养的PBMC中检测到更多的p24，但对在血浆中培养的细胞中的p24表达没有影响。p24的减少与较低的细胞活力无关，也不受抗凝剂枸橼酸盐-磷酸盐-葡萄糖对钙依赖性淋巴细胞活化的影响。在自体和同源血清中生长的细胞之间，或在血清阳性奶牛的自体和同源血浆中生长的细胞之间，p24抑制效力没有观察到显著差异。
血清阴性奶牛的血浆以及BLV血清阳性奶牛的血浆和血清中存在阻断活性。这种活性可能在体内调节病毒潜伏期和前病毒表达方面很重要。
