Evaluation of the deletion of the African swine fever virus gene O174L from the genome of the Georgia isolate

Authors: Ramirez-Medina, Elizabeth; Velazquez, Lauro; RAI, AYUSHI - Oak Ridge Institute For Science And Education (ORISE); Espinoza, Nallely; VALLADARES, ALYSSA - Oak Ridge Institute For Science And Education (ORISE); Silva, Ediane; Burton, Leeanna; Spinard Iii, Edward; MEYERS, AMANDA - Oak Ridge Institute For Science And Education (ORISE); RISATTI, GUILLERMO - University Of Connecticut; CALVELAGE, STEN - Friedrich-Loeffler-institute; BLOME, SANDRA - Friedrich-Loeffler-institute; Gladue, Douglas; Borca, Manuel

Submitted to: Viruses
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/16/2023
Publication Date: 10/23/2023
Citation: Ramirez Medina, E., Velazquez Salinas, L., Rai, A., Espinoza, N.N., Valladares, A., Silva, E.B., Burton, L.J., Spinard III, E.J., Meyers, A., Risatti, G., Calvelage, S., Blome, S., Gladue, D.P., Borca, M.V. 2023. Evaluation of the deletion of the African swine fever virus gene O174L from the genome of the Georgia isolate. Viruses. 15(10). Article 2134. https://doi.org/10.3390/v15102134.
DOI: https://doi.org/10.3390/v15102134

Interpretive Summary: African swine fever virus (ASFV) is currently causing a world-wide pandemic of a highly lethal disease in domestic swine and wild boar. In this study we evaluate the proteins involved in genome replication, by deleting an ASFV protein, when deleted we saw that there was no difference in pathogenesis or replication of ASFV.

Technical Abstract: African swine fever virus (ASFV) is a structurally complex, double stranded DNA virus which causes African swine fever (ASF), a contagious disease affecting swine. ASF is currently affecting pork production in a large geographical region including Eurasia and the Caribbean. ASFV has a large genome which harbors more than 160 genes, but most of these genes’ functions have not been experimentally characterized. One of these genes is the O174L, which has been experiment-tally shown to function as a small DNA polymerase. Here, we demonstrate that the deletion of the O174L gene from the genome of the virulent strain ASFV Georgia2010 (ASFV-G) does not significantly affect virus replication in vitro nor in vivo. A recombinant virus, having deleted the O174L, ASFV-G-deltaO174L, was developed to study the effect of the O174L in replication in swine macrophages cultures in vitro and disease production when inoculated in pigs. Results demonstrated that ASFV-G-deltaO174L has similar replication kinetics to parental ASFV-G in swine macrophage cultures. In addition, animals intramuscularly inoculated with 102 HAD50 of ASFV-G-deltaO174L present a clinical form of the disease which is indistinguishable from that induced by the parental virulent strain ASFV-G. All animals develop a lethal disease, being euthanized around day 7 post infection. Therefore, although O174L is a well characterized DNA polymerase, its function is apparently not critical for the process of virus replication, both in vitro and in vivo, nor for disease production in domestic pigs.