Electron Microscopic Study of Tissue Cultures Infected with Simian Haemorrhagic Fever Virus

Abstract

SUMMARYThe morphology and development of simian haemorrhagic fever virus was studied in tissue cultures infected with low multiplicities of virus. Early cytoplasmic lesions which were observed 24 hr after infection consisted of increased concentrations of polysomes and small vesicles IOO nm. in diameter filled with densely staining fibrillar material. As the lesions progressed, thickened membranous structures developed at the periphery of the vesicles. The membranes appeared to lengthen and thicken by a process of end-to-end and side-to-side fusion. Serial sections demonstrated that the fused, thickened structures were lamellae. Their role in the morphogenesis of simian haemorrhagic fever virus is not presently known.Spherical virus particles measuring 4o to 45 nm. in diameter appeared in cells by 72 hr after infection. Infected cells contained vacuoles which enclosed accumulations of enveloped spherical particles. Some particles appeared to be budding into vacuoles.

The molecular biology of arteriviruses.

“…1) and are released by exocytosis (Magnusson et al, 1970 ;Wood et al, 1970 ;Stueckemann et al, 1982 ;. The generation of aberrant nucleocapsid structures and\or unusual elongated virions was observed for various arteriviruses (Stueckemann et al, 1982 ;Wada et al, 1995).…”

“…2 a, Breese & McCollum, 1970 ;Wood et al, 1970 ;Stueckemann et al, 1982 ;Pol et al, 1997). Although the origin and function of these membrane structures are unclear, they do not appear to be involved in virus assembly.…”

Studies on Simian Hemorrhagic Fever virus nucleocapsids

“…The banding of SHF virus nuclcocapsids in a consistent way after treatment in conditions which would release the lipoprotein of the envelope while leaving the virus core intact (21), confirms the existence of such a structure suggested by electromicroscopic observation of S H F infected cells (24).…”

“…Electron microscopy of negatively stained S H F virus has shown them to be spherical particles with an average diameter of 48 nm (22), and covered b y tight fitting envdopes which mask the ultrastructure of the internal nucleocapsids. Diseased ceils were observed to have core-like structures of an average diameter of 25 nm (24).…”

“…However, it has not been subclassified within any of the currently recognized Togavirus genera, since to date, this virus was unrelated serologically to any of the arbovirus known to cause hemorrhagic disease (20,24).…”