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Gladue DP, O’Donnell V, Ramirez-Medina E, Rai A, Pruitt S, Vuono EA, Silva E, Velazquez-Salinas L, Borca MV. Deletion of CD2-Like (CD2v) and C-Type Lectin-Like (EP153R) Genes from African Swine Fever Virus Georgia-∆9GL Abrogates Its Effectiveness as an Experimental Vaccine. Viruses 2020; 12:E1185. [PMID: 33092057 PMCID: PMC7590024 DOI: 10.3390/v12101185] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Revised: 10/14/2020] [Accepted: 10/16/2020] [Indexed: 01/31/2023] Open
Abstract
African swine fever virus (ASFV) is currently the most dreaded infectious disease affecting the global swine production industry. There is no commercial vaccine available, making the culling of infected animals the current solution to control outbreaks. Effective experimental vaccines have been developed by deleting virus genes associated with virulence. Deletion of the ASFV 9GL gene (∆9GL) has resulted in the attenuation of different ASFV strains, although the degree of attenuation varies across isolates. Here, we investigated the possibility of the increased safety of the experimental vaccine strain ASFV-G-Δ9GL by deleting two additional virus genes involved in pathogenesis, CD2v, a CD2 like viral encoded gene from the EP402R open reading frame (ORF), and C-type lectin-like viral gene, encoded from the EP153R ORF. Two new recombinant viruses were developed, ASFV-G-Δ9GL/ΔCD2v and ASFV-G-Δ9GL/ΔCD2v/ΔEP153R, harboring two and three gene deletions, respectively. ASFV-G-Δ9GL/ΔCD2v/ΔEP153R, but not ASFV-G-Δ9GL/ΔCD2v, had a decreased ability to replicate in vitro in swine macrophage cultures when compared with parental ASFV-G-Δ9GL. Importantly, ASFV-G-Δ9GL/ΔCD2v and ASFV-G-Δ9GL/ΔCD2v/ΔEP153R induced almost undetectable viremia levels when inoculated into domestic pigs and failed to protect them against challenge with parental virulent ASFV-Georgia, while ASFV-G-Δ9GL offered robust protection during challenge. Therefore, the deletion of CD2-like and C-type lectin-like genes significantly decreased the protective potential of ASFV-G-Δ9GL as a vaccine candidate. This study constitutes an example of the unpredictability of genetic manipulation involving the simultaneous deletion of multiple genes from the ASFV genome.
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Affiliation(s)
- Douglas P. Gladue
- Plum Island Animal Disease Center, ARS, USDA, Greenport, NY 11944, USA; (V.O.); (E.R.-M.); (A.R.); (S.P.); (E.A.V.); (E.S.); (L.V.-S.)
| | - Vivian O’Donnell
- Plum Island Animal Disease Center, ARS, USDA, Greenport, NY 11944, USA; (V.O.); (E.R.-M.); (A.R.); (S.P.); (E.A.V.); (E.S.); (L.V.-S.)
- Plum Island Animal Disease Center, APHIS, USDA, Greenport, NY 11944, USA
| | - Elizabeth Ramirez-Medina
- Plum Island Animal Disease Center, ARS, USDA, Greenport, NY 11944, USA; (V.O.); (E.R.-M.); (A.R.); (S.P.); (E.A.V.); (E.S.); (L.V.-S.)
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, USA
| | - Ayushi Rai
- Plum Island Animal Disease Center, ARS, USDA, Greenport, NY 11944, USA; (V.O.); (E.R.-M.); (A.R.); (S.P.); (E.A.V.); (E.S.); (L.V.-S.)
- Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN 37830, USA
| | - Sarah Pruitt
- Plum Island Animal Disease Center, ARS, USDA, Greenport, NY 11944, USA; (V.O.); (E.R.-M.); (A.R.); (S.P.); (E.A.V.); (E.S.); (L.V.-S.)
- Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN 37830, USA
| | - Elizabeth A. Vuono
- Plum Island Animal Disease Center, ARS, USDA, Greenport, NY 11944, USA; (V.O.); (E.R.-M.); (A.R.); (S.P.); (E.A.V.); (E.S.); (L.V.-S.)
- Department of Pathobiology and Population Medicine, Mississippi State University, Mississippi State, MS 39762, USA
| | - Ediane Silva
- Plum Island Animal Disease Center, ARS, USDA, Greenport, NY 11944, USA; (V.O.); (E.R.-M.); (A.R.); (S.P.); (E.A.V.); (E.S.); (L.V.-S.)
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, USA
| | - Lauro Velazquez-Salinas
- Plum Island Animal Disease Center, ARS, USDA, Greenport, NY 11944, USA; (V.O.); (E.R.-M.); (A.R.); (S.P.); (E.A.V.); (E.S.); (L.V.-S.)
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, USA
| | - Manuel V. Borca
- Plum Island Animal Disease Center, ARS, USDA, Greenport, NY 11944, USA; (V.O.); (E.R.-M.); (A.R.); (S.P.); (E.A.V.); (E.S.); (L.V.-S.)
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