Ultrastructural morphogenesis of salmonid alphavirus 1.
Studies on the ultrastructural morphogenesis of viruses give an insight into how the host cell mechanisms are utilized for new virion synthesis. A time course examining salmonid alphavirus 1 (SAV 1) assembly was performed by culturing the virus on Chinook salmon embryo cells (CHSE-214). Different stages of viral replication were observed under electron microscopy. Virus-like particles were observed inside membrane-bound vesicles as early as 1 h following contact of the virus with the cells. Membrane-dependent replication complexes were observed in the cytoplasm of the cells, with spherules found at the periphery of late endosome-like vacuoles. The use of intracellular membranes for RNA replication is similar to other positive-sense single-stranded RNA (+ssRNA) viruses. The number of Golgi apparatus and associated vacuoles characterized by 'fuzzy'-coated membranes was greater in virus-infected cells. The mature enveloped virions started to bud out from the cells at approximately 24 h post-infection. These observations suggest that the pathway used by SAV 1 for the generation of new virus particles in vitro is comparable to viral replication observed with mammalian alphaviruses but with some interesting differences.
School of Natural Sciences, Institute of Aquaculture, University of Stirling, Stirling, UK. tkh1@stir.ac.uk
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Herath
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Ferguson
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Thompson
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Adams
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Richards
D000524:Alphavirus / Q000502:physiology* / Q000648:ultrastructure*; D000818:Animals; D002460:Cell Line; D046529:Microscopy, Electron, Transmission; D012487:Salmonidae / Q000821:virology; D014779:Virus Replication