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Title: Interaction of structural core protein of Classical Swine Fever Virus with endoplasmic reticulum-associated degradation pathway protein OS9

item GLADUE, DOUGLAS - University Of Connecticut
item O'DONNELL, VIVIAN - University Of Connecticut
item FERNANDEZ-SAINZ, IGNACIO - University Of Connecticut
item FLETCHER, PAIGE - Oak Ridge Institute For Science And Education (ORISE)
item BAKER-BRANSTETTER, RYAN - Oak Ridge Institute For Science And Education (ORISE)
item Holinka-Patterson, Lauren
item Sanford, Brenton
item CARLSON, JOLENE - Kansas State University
item LU, ZHIQIANG - Us Deparment Of Homeland Security
item Borca, Manuel

Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2014
Publication Date: 7/1/2014
Citation: Gladue, D.P., O'Donnell, V., Fernandez-Sainz, I.J., Fletcher, P., Baker-Branstetter, R., Holinka-Patterson, L.G., Sanford, B.J., Carlson, J., Lu, Z., Borca, M.V. 2014. Interaction of structural core protein of Classical Swine Fever Virus with endoplasmic reticulum-associated degradation pathway protein OS9. Virology. 460-461:173-179. DOI: 10.1016/j.virol.2014.05.008.

Interpretive Summary: Classical swine fever virus (CSFV) causes an important and costly disease of swine. We are investigating the role of different viral proteins in the pathogenesis of CSFV. The Core protein forms the capsid protecting the virus genetic material. Besides this structural function, Core protein also has been involved in the process of producing disease in infected swine. To discover additional Core protein functions we attempted to identify swine host proteins that directly interact with Core during the process of virus infection. For that purpose we use a special methodology known as yeast two hybrid system. Among the identified host proteins one of them, called OS9, was further studied in its interaction with CSFV Core protein. We first identify the area of Core protein that actually physically interact with OS9 and then we produce a recombinant CSFV that has mutated that particular area in its Core protein. Using this mutant virus we showed that interaction of CSFV Core and host OS9 protein is important for the process of virus replication. This information may be useful for the development of alternative methodologies to control virus spread among susceptible animals.

Technical Abstract: Classical Swine Fever Virus (CSFV) Core protein is involved in virus RNA protection, transcription regulation and virus virulence. To discover additional Core protein functions a yeast two-hybrid system was used to identify host proteins that interact with Core. Among the identified host proteins, the osteosarcoma amplified 9 protein (OS9) was further studied. Using alanine scanning mutagenesis, the OS9 binding site in the CSFV Core protein was identified, between Core residues ^90IAIM^93, near a putative cleavage site. Truncated versions of Core were used to show that OS9 binds a polypeptide representing the 12 C-terminal Core residues. Cells transfected with a double-fluorescent labeled Core construct demonstrated that co-localization of OS9 and Core occurred only on unprocessed forms of Core protein. A recombinant CSFV containing Core protein where residues ^90IAIM^93 were substituted by alanines showed no altered virulence in swine, but a significant decreased ability to replicate in cell cultures.