A cell culture-adapted vaccine virus against the current pandemic African swine fever virus strain

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

Submitted to: Nature Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2021
Publication Date: 6/24/2021
Citation: Borca, M.V., Rai, A., Ramirez-Medina, E., Silva, E.B., Velazquez-Salinas, L., Vuono, E., Espinoza, N.N., Pruitt, S.E., Gladue, D.P. 2021. A cell culture-adapted vaccine virus against the current pandemic African swine fever virus strain. Nature Communications. https://doi.org/10.1128/JVI.00123-21.
DOI: https://doi.org/10.1128/JVI.00123-21

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 is no available vaccine for ASF, and currently only experimental live attenuated vaccines are derived from deletions of individual genes in the ASFV genome. All experimental vaccines have only been able to grow in primary cells. In this study we identified a deletion in ASFV, that allows for growth in cell cultures.

Technical Abstract: African swine fever virus (ASFV) causes a virulent, deadly infection in wild and domestic swine, and is currently causing a pandemic covering a contiguous geographical area from Central and Eastern Europe to Asia. No commercial vaccines are available to prevent African swine fever (ASF), resulting in devastating economic losses to the swine industry. The most advanced vaccine candidates are live attenuated strains developed using genetically modified virulent parental virus. Recently we developed a vaccine candidate, ASFV-G-'I177L, by deleting the I177L gene from the genome of the highly virulent pandemic ASFV strain Georgia (ASFV-G). ASFV-G-'I177L is safe and highly efficacious in challenge studies using parental ASFV-G. Large-scale production of ASFV-G-'I177L has been limited because it can only efficiently replicate in primary swine macrophages. Here we present the development of an ASFV-G-'I177L derivative strain, ASFV-G-'I177L/'LVR, that efficiently replicates in a stable porcine cell line. In challenge studies, ASFV-G-'I177L/'LVR maintained the same level of attenuation, immunogenic characteristics and protective efficacy as ASFV-G-'I177L. ASFV-G-'I177L/'LVR is the first rationally designed ASF vaccine candidate that can be used for large-scale commercial vaccine manufacturing.