Evaluation of an ASFV RNA helicase gene A859L for virus replication and swine virulence

Authors: Ramirez-Medina, Elizabeth; VUONO, ELIZABETH - University Of Mississippi; Pruitt, Sarah; RAI, AYUSHI - Oak Ridge Institute For Science And Education (ORISE); Espinoza, Nallely; VELAZQUEZ-SALINAS, LAURO - University Of Mississippi; Gladue, Douglas; Borca, Manuel

Submitted to: Viruses
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2021
Publication Date: 12/21/2021
Citation: Ramirez Medina, E., Vuono, E., Pruitt, S.E., Rai, A., Espinoza, N.N., Velazquez-Salinas, L., Gladue, D.P., Borca, M.V. 2021. Evaluation of an ASFV RNA helicase gene A859L for virus replication and swine virulence. Viruses. https://doi.org/10.3390/v14010010.
DOI: https://doi.org/10.3390/v14010010

Interpretive Summary: African swine fever virus (ASFV) causes a devastating disease in swine, called African swine fever (ASF), that is currently spreading across Europe and Asia. There is no available vaccine for ASF, and currently only experimental live attenuated vaccines are derived from deletions of individual genes in the ASFV genome. In this study we were able to delete a structural protein in ASFV, however deletion of this helicase protein did not have any effect on virus replication or virulence.

Technical Abstract: African swine fever virus (ASFV) is producing a devastating pandemic that, since 2007, has spread to a contiguous geographical area from central Europe to Asia. In July 2021, ASFV was detected in the Dominican Republic, the first report of the disease in the Americas in more than 40 years. ASFV is a large highly complex virus harboring a large dsDNA genome that encodes for more than 160 genes. The majority of these genes have not been functionally characterized. Bioinformatics analysis predicts that ASFV gene A859L encodes for a RNA helicase, although its function has not yet been experimentally assessed. Here we evaluated the role of the A859L gene during virus replication in cell cultures and during infection in swine. For that purpose, a recombinant virus (ASFV-G-'A859L) harboring a deletion of the A859L gene was developed using the highly virulent ASFV Georgia (ASFV-G) isolate as template. Recombinant ASFV-G-'A859L replicates in swine macrophage cultures as efficiently as the parental virus ASFV-G, demonstrating that the A859L gene is non-essential for ASFV replication. Experimental infection of domestic pigs demonstrated that ASFV-G-'A859L replicates as efficiently and induces a clinical disease undistinguishable from that caused by the parental ASFV-G. These studies conclude that the predicted RNA helicase gene A859L is not involved in the processes of virus replication or disease production in swine.