Lyden T W, Johnson P M, Mwenda J M, Rote N S
Department of Microbiology/Immunology, Wright State University School of Medicine, Dayton, Ohio 45435.
Biol Reprod. 1994 Jul;51(1):152-7. doi: 10.1095/biolreprod51.1.152.
Human placental endogenous retroviral (ERV) particle isolates were investigated by ultrastructural evaluation. Although retrovirus-like structures in normal human placental tissue sections have been described, the precise nature of these particles has not previously been defined. By direct electron microscopic (EM) observation of placental ERV isolates that display retroviral reverse transcriptase (RTase) activity and a buoyant density consistent with type-C retroviruses (1.17 g/ml on sucrose), we have shown these to contain particles with characteristic retroviral ultrastructural features. Samples were stained with 1.0% phosphotungstic acid (PTA), 0.5% uranyl acetate (UA), and low-angle-shadowed with platinum/palladium. Isolated placental ERV particles have an apparent diameter of approximately 120 nm, are membrane-bound with a short surface fringe, and contain capsid particles (about 90 nm in diameter) within an internal matrix structure. These observations support the view that human placental cells normally express ERV particles.
通过超微结构评估对人胎盘内源性逆转录病毒（ERV）颗粒分离物进行了研究。尽管已描述了正常人胎盘组织切片中的逆转录病毒样结构，但这些颗粒的确切性质此前尚未明确。通过对显示逆转录病毒逆转录酶（RTase）活性且浮力密度与C型逆转录病毒一致（在蔗糖上为1.17 g/ml）的胎盘ERV分离物进行直接电子显微镜（EM）观察，我们发现这些分离物含有具有特征性逆转录病毒超微结构特征的颗粒。样品用1.0%磷钨酸（PTA）、0.5%醋酸铀（UA）染色，并用铂/钯进行低角度阴影投射。分离出的胎盘ERV颗粒的表观直径约为120 nm，有膜包裹且表面有短边缘，内部基质结构内含有衣壳颗粒（直径约90 nm）。这些观察结果支持人胎盘细胞正常表达ERV颗粒这一观点。
