title: Low temperature-dependent salmonid alphavirus glycoprotein processing and recombinant virus-like particle formation.
abstract: Pancreas disease (PD) and sleeping disease (SD) are important viral scourges in aquaculture of Atlantic salmon and rainbow trout. The etiological agent of PD and SD is salmonid alphavirus (SAV), an unusual member of the Togaviridae (genus Alphavirus). SAV replicates at lower temperatures in fish. Outbreaks of SAV are associated with large economic losses of ~17 to 50 million $/year. Current control strategies rely on vaccination with inactivated virus formulations that are cumbersome to obtain and have intrinsic safety risks. In this research we were able to obtain non-infectious virus-like particles (VLPs) of SAV via expression of recombinant baculoviruses encoding SAV capsid protein and two major immunodominant viral glycoproteins, E1 and E2 in Spodoptera frugiperda Sf9 insect cells. However, this was only achieved when a temperature shift from 27°C to lower temperatures was applied. At 27°C, precursor E2 (PE2) was misfolded and not processed by host furin into mature E2. Hence, E2 was detected neither on the surface of infected cells nor as VLPs in the culture fluid. However, when temperatures during protein expression were lowered, PE2 was processed into mature E2 in a temperature-dependent manner and VLPs were abundantly produced. So, temperature shift-down during synthesis is a prerequisite for correct SAV glycoprotein processing and recombinant VLP production.
authors: Laboratory of Virology, Wageningen University, Wageningen, The Netherlands.
authors: Stefan W
authors: SW
authors: Metz
authors: Femke
authors: F
authors: Feenstra
authors: Stephane
authors: S
authors: Villoing
authors: Marielle C
authors: MC
authors: van Hulten
authors: Jan W
authors: JW
authors: van Lent
authors: Joseph
authors: J
authors: Koumans
authors: Just M
authors: JM
authors: Vlak
authors: Gorben P
authors: GP
authors: Pijlman
mesh_terms: D000524:Alphavirus / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D002467:Cell Nucleus / Q000378:metabolism / Q000648:ultrastructure; D003080:Cold Temperature; D006023:Glycoproteins / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D011995:Recombination, Genetic / Q000235:genetics; D012487:Salmonidae / Q000821:virology*; D018411:Spodoptera / Q000166:cytology; D014764:Viral Proteins / Q000378:metabolism*; D014771:Virion / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D006023:Glycoproteins; D014764:Viral Proteins