Doughri A M, Storz J, Hajer I, Fernando H S
Exp Mol Pathol. 1976 Dec;25(3):355-70. doi: 10.1016/0014-4800(76)90045-9.
The morphology and morphogenesis of virus strain LY-138 recovered from neonatal diarrheic calves were investigated by electron microscopy using negativestaining techniques and ultrathin sectioning. Purified viral particles were spherical in shape and measured 90 nm in average diameter in negatively stained preparations. Pleomorphic forms were also present. The virions had envelopes with petal-shaped projections characteristic of coronaviruses. In ultrathin sections, cores in viral factories were round with a diameter of 50–60 nm. Most of these cores were electron dense but some had an electron-lucent center. In cytoplasmic vacuoles, Golgi vesicles, and on the apical plasmalemma of intestinal epithelial cells, the virions were round or ellipsoidal in shape, measuring 70–80 nm in diameter, and had fine thread-like projections on their surfaces. Uptake of virus occurred through fusion of viral envelopes with the plasmalemma of the microvillous border or by entry into intercellular spaces and interaction with the lateral cell membranes of adjacent intestinal epithelial cells. As a result of this interaction, the lateral cell membranes became altered and ill-defined. During the early stage of infection, the rough andasmooth elements of the endoplasmic reticulum became distended with electron-dense granulofibrillar material. This material accumulated subsequently as well-defined, smooth membrane-bound areas mainly in the apical cytoplasm of infected cells. These structures were considered to be viral factories. The morphogenesis of virus occurred mainly through condensation of the electron-dense, granulo-fibrillar material into viral cores in cytoplasmic viral factories or within the distended cisternes of the rough endoplasmic reticulum. Viral envelopment occurred on membranes of cytoplasmic vacuoles, Golgi vesicles, or in association with membranes of viral factories. Release of virus from infected cells occurred by lysis and fragmentation of the apical plasmalemma and flow of the cytoplasm with its contents into the gut lumen. Release also occurred by digestion and lysis of extruded infected cells or by fusion of virus-containing cytoplasmic vacuoles with the apical plasmalemma and liberation of their contents.
采用负染技术和超薄切片技术，通过电子显微镜对从新生腹泻犊牛中分离得到的病毒株LY - 138的形态和形态发生进行了研究。纯化的病毒粒子呈球形，在负染制剂中平均直径为90 nm。也存在多形性形态。病毒粒子具有包膜，包膜上有冠状病毒特有的花瓣状突起。在超薄切片中，病毒工厂中的核心呈圆形，直径为50 - 60 nm。这些核心大多数电子密度高，但有些有电子透明中心。在细胞质空泡、高尔基体小泡以及肠上皮细胞的顶端质膜上，病毒粒子呈圆形或椭圆形，直径为70 - 80 nm，表面有细的丝状突起。病毒通过病毒包膜与微绒毛边界的质膜融合，或进入细胞间隙并与相邻肠上皮细胞的侧细胞膜相互作用而进入细胞。这种相互作用的结果是，侧细胞膜发生改变且界限不清。在感染早期，内质网的粗面和滑面成分被电子密度高的颗粒状纤维物质扩张。这种物质随后积累形成主要位于感染细胞顶端细胞质中的界限分明的、光滑的膜结合区域。这些结构被认为是病毒工厂。病毒的形态发生主要通过电子密度高的颗粒状纤维物质在细胞质病毒工厂或粗面内质网扩张的潴泡内浓缩形成病毒核心。病毒包膜在细胞质空泡膜、高尔基体小泡膜上形成，或与病毒工厂的膜相关联。病毒从感染细胞中释放是通过顶端质膜的溶解和破碎，以及细胞质及其内容物流入肠腔实现的。释放也通过挤压的感染细胞的消化和溶解，或通过含病毒的细胞质空泡与顶端质膜融合并释放其内容物而发生。
