SERTA domain containing protein 1 (SERTAD1) interacts with classical swine fever virus structural glycoprotein E2 which is involved in virus virulence in swine

Authors: VUONO, ELIZABETH - University Of Mississippi; RAMIREZ-MEDINA, ELIZABETH - University Of Connecticut; Azzinaro, Paul; BERGGREN, KEITH - Princeton University; RAI, AYUSHI - Oak Ridge Institute For Science And Education (ORISE); PRUITT, SARAH - Oak Ridge Institute For Science And Education (ORISE); SILVA, EDIANE - University Of Kansas; VELAZQUEZ-SALINAS, LAURO - University Of Kansas; Borca, Manuel; Gladue, Douglas

Submitted to: Journal of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2020
Publication Date: 4/9/2020
Citation: Vuono, E., Ramirez-Medina, E., Azzinaro, P.A., Berggren, K., Rai, A., Pruitt, S., Silva, E., Velazquez-Salinas, L., Borca, M.V., Gladue, D.P. 2020. SERTA domain containing protein 1 (SERTAD1) interacts with classical swine fever virus structural glycoprotein E2 which is involved in virus virulence in swine. Journal of Virology. https://doi.org/10.3390/v12040421.
DOI: https://doi.org/10.3390/v12040421

Interpretive Summary: Classical swine fever virus (CSFV) causes a devastating disease in swine, one protein of this virus called E2 is probably the most important component of virus due to its involvement in many virus activities, particularly interacting with the hosts ie pig cells. Here we identified a protein in pig cells that interact with E2, this protein is called SERTAD1. During virus infection, SERTAD1 is responsible for movement of proteins inside the cells. The E2 amino acid residues mediating the interaction with SERTAD1 were also identified. A genetically modified CSFV was created harboring mutations disrupting E2-SERTAD1 interaction. Disrupting the E2-SERTAD1 interaction resulted in attenuation of the virus when tested in pig. This information provides possible mechanisms of virus attenuation toward development of improved CSF vaccines.

Technical Abstract: E2 is the major structural glycoprotein of classical swine fever virus (CSFV). E2 has been shown to be involved in important virus functions such as replication and virulence in swine. Using the yeast two-hybrid system, we have previously identified several host proteins specifically interacting with CSFV E2. Here, we analyze the protein interaction of E2 with SERTA domain containing protein 1 (SERTAD1), a factor involved in the stimulation of the transcriptional activities of different host genes. We have confirmed that the interaction between these two proteins occurs in CSFV-infected swine cells by using a proximity ligation assay and confocal microscopy. Amino acid residues in the CSFV E2 protein that are responsible for mediating the interaction with SERTAD1 were mapped by a yeast two-hybrid approach using a randomly mutated E2 library. Using that information, a recombinant CSFV mutant (E2'SERTAD1v) which harbors substitutions in those residues mediating the protein-interaction with SERTAD1 was developed and used to study the role of the E2-SERTAD1 interaction in viral replication and virulence in swine. CSFV E2'SERTAD1v showed a clear decreased ability to replicate in the SK6 swine cell line and a more severe replication effect in primary swine macrophage cultures. Importantly, 80% of animals infected with E2'SERTAD1v survived challenge infection, remaining clinically normal during the 21-day observational period. This result would indicate that the ability of CSFV E2 to bind host SERTAD1 protein during infection plays a critical role in virus virulence.