Development of a novel African swine fever virus (ASFV) live attenuated vaccine candidate: deletion of A137R gene drastically attenuates Georgia strain and induce protection against the virulent challenge

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

Submitted to: Journal of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2021
Publication Date: 8/18/2021
Citation: Gladue, D.P., Ramirez Medina, E., Vuono, E., Silva, E.B., Rai, A., Pruitt, S.E., Espinoza, N.N., Velazquez-Salinas, L., Borca, M.V. 2021. Development of a novel African swine fever virus (ASFV) live attenuated vaccine candidate: deletion of A137R gene drastically attenuates Georgia strain and induce protection against the virulent challenge. Journal of Virology. https://doi.org/10.1128/JVI.01139-21.
DOI: https://doi.org/10.1128/JVI.01139-21

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 are several experimental vaccines for ASF, however some of them have residual effects and require additional changes to increase safety. Here we evaluate a new genetic deletion in ASF that attenuates the virus, and serves as a vaccine candidate for the current Pandemic strain of ASFV.

Technical Abstract: African swine fever virus (ASFV) is causing a devastating pandemic in domestic and wild swine within an extended geographical area from Central Europe to East Asia resulting in economic losses for the regional swine industry. There are no commercial vaccines, therefore disease control relies on identification and culling of infected animals. We report here that the deletion of the ASFV gene A137R from the highly virulent ASFV-Georgia2010 (ASFV-G) isolate induces a significant attenuation of virus virulence in swine. A recombinant virus lacking the A137R gene, ASFV-G-'A137R, was developed to assess the role of this gene in ASFV virulence in domestic swine. Animals inoculated intramuscularly with 102 HAD50 of ASFV-G-'A137R remained clinically healthy during the 28 day observational period. All animals inoculated with ASFV-G-'A137R had medium to high viremia titers and developed a strong virus-specific antibody response. No virus transmission to a cohabitating naïve animal was observed. Importantly, all ASFV-G-'A137R-inoculated animals were protected when challenged with the virulent parental strain ASFV-G. ASFV-G-'A137R is a novel potential live attenuated vaccine candidate and one of the few experimental vaccine strains reported to induce protection against the highly virulent ASFV Georgia virus that is the cause of the current Eurasian pandemic.