Lemon S M, Jansen R W, Newbold J E
J Virol. 1985 Apr;54(1):78-85. doi: 10.1128/JVI.54.1.78-85.1985.
Although hepatitis A virus (HAV) released by infected BS-C-1 cells banded predominantly at 1.325 g/cm3 (major component) in CsCl, smaller proportions of infectious virions banded at 1.42 g/cm3 (dense HAV particles) and at 1.27 g/cm3 (previously unrecognized light HAV particles). cDNA-RNA hybridization confirmed the banding of viral RNA at each density, and immune electron microscopy demonstrated apparently complete viral particles in each peak fraction. The ratio of the infectivity (radioimmunofocus assay) titer to the antigen (radioimmunoassay) titer of the major component was approximately 15-fold greater than that of dense HAV particles and 4-fold that of light HAV particles. After extraction with chloroform, the buoyant density of light and major component HAV particles remained unchanged, indicating that the lower density of the light particles was not due to association with lipids. Light particles also banded at a lower density (1.21 g/cm3) in metrizamide than did the major component (1.31 g/cm3). Dense HAV particles, detected by subsequent centrifugation in CsCl, were indistinguishable from the major component when first banded in metrizamide (1.31 g/cm3). However, dense HAV particles recovered from CsCl subsequently banded at 1.37 g/cm3 in metrizamide. Electrophoresis of virion RNA under denaturing conditions demonstrated that dense, major-component, and light HAV particles all contained RNA of similar length. Thus, infectious HAV particles released by BS-C-1 cells in vitro consist of three distinct types which band at substantially different densities in CsC1, suggesting different capsid structures with varied permeability to cesium or different degrees of hydration.
尽管受感染的BS-C-1细胞释放的甲型肝炎病毒（HAV）在氯化铯中主要在1.325 g/cm³处形成条带（主要成分），但较小比例的感染性病毒粒子在1.42 g/cm³处形成条带（致密HAV颗粒），在1.27 g/cm³处也有形成条带（此前未被识别的轻型HAV颗粒）。cDNA-RNA杂交证实了病毒RNA在每个密度下的条带情况，免疫电子显微镜显示每个峰级分中都有明显完整的病毒颗粒。主要成分的感染性（放射免疫聚焦测定）滴度与抗原（放射免疫测定）滴度之比大约比致密HAV颗粒高15倍，是轻型HAV颗粒的4倍。用氯仿提取后，轻型和主要成分HAV颗粒的浮力密度保持不变，这表明轻型颗粒较低的密度并非由于与脂质结合。在甲泛影酰胺中，轻型颗粒的条带密度（1.21 g/cm³）也低于主要成分（1.31 g/cm³）。通过随后在氯化铯中离心检测到的致密HAV颗粒，首次在甲泛影酰胺中条带时（1.31 g/cm³）与主要成分无法区分。然而，从氯化铯中回收的致密HAV颗粒随后在甲泛影酰胺中的条带密度为1.37 g/cm³。在变性条件下对病毒粒子RNA进行电泳表明，致密、主要成分和轻型HAV颗粒都含有长度相似的RNA。因此，BS-C-1细胞在体外释放的感染性HAV颗粒由三种不同类型组成，它们在氯化铯中的条带密度差异很大，这表明衣壳结构不同，对铯的渗透性不同或水化程度不同。
