感染细胞中SARS相关病毒的形态学观察

Ultrastructural characteristics of severe acute respiratory syndrome associated virus in infected cells

目的 用电子显微镜观察严重急性呼吸综合征(SARS)患者标本感染细胞,为SARS病原体的分离鉴定提供形态学资料。方法 以北京和广州地区SARS病例尸检肺组织和鼻咽拭子标本感染Vero E6细胞,通过对培养上清液和病变细胞超薄切片观察,了解病毒的大小、形态、在感染细胞中的分布和装配情况,初步判定病毒的分类。结果 在3价标本感染的细胞培养液和病变细胞中均查见病毒,病毒颗粒多呈圆形或椭圆形,大小80～120nm,外周有冠状排列的纤突。在广州肺组织标本感染的细胞中还查见大量的短杆状和少量肾形、不规则形的病毒颗粒,大小100～200nm×60～90nm,其他标本感染细胞中这种形态的病毒颗粒较少见。切片中见病毒主要分布在细胞质的内质网池、高尔基体、空泡、包涵体内和细胞外,呈空心和实心两种形式。包涵体内病毒颗粒排列紧密,其大小、形态不一。病毒以胞饮或膜融合形式进入细胞,以出芽方式增殖。结论 电镜查见SARS病例标本中分离出典型的圆形或椭圆形的冠状病毒,与文献报道的SARS相关新型冠状病毒相符。同时我们也发现了另一种以短杆状为主,偶见梨形、肾形、多形性的病毒颗粒,它们在SARS研究中的意义有待进一步探讨。

Objective Electron microscopical study of infected cells to identify the pathogenic agent of severe acute respiratory syndrome (SARS). Methods Vero E6 cells were inoculated with lung autopsy samples or nasopharyngeal swabs from SARS patients of Beijing and Guangzhou. The supernatant and cultured cells exhibiting identifiable cytopathic effect (CPE) were prepared for electron microscopic srudy. Results Examination of CPE cells on thin-section revealed characteristic coronavirus particles within the cisternae of endoplasmic reticulum, Golgi apparatus, vesicles and extracellular space. They were mainly spherical or oval in shape, annular or dense, about 80 nm in diameter. Negative-stain electron microscopy identified coronavirus particles in culture supernatant, 80-120 nm in diameter, with club-shaped surface projections. Elongated, rod-, kidney- or other irregular shaped virons with the size of 100-200 nm by 60-90 nm were also found in the cultured cells infected with the lung samples from the Guangdong patients. Infectious virons entered cells by endocytosis or membrane fusion and released through a budding process. Conclusions These data indicate a novel coronavirus as the causative agent of SARS. Most viral particles showed typical characteristics of coronavirus. The potential role of special shape viruses is expected to be further investigated.