ASF Vaccine Candidate ASFV-G-ΔI177L Does Not Exhibit Residual Virulence in Long-Term Clinical Studies

Journal Article · 01 June 2023 · Pathogens

DOI: https://doi.org/10.3390/pathogens12060805 · OSTI ID:2471316

Borca, Manuel V. ^[1]; Ramirez-Medina, Elizabeth ^[1]; Silva, Ediane  ^[1]; Rai, Ayushi ^[2]; Espinoza, Nallely ^[1]; Velazquez-Salinas, Lauro ^[1]; Gladue, Douglas P.  ^[1]

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1. US Dept. of Agriculture (USDA), Greenport, NY (United States). Agricultural Research Service (ARS), Plum Island Animal Disease Center
2. US Dept. of Agriculture (USDA), Greenport, NY (United States). Agricultural Research Service (ARS), Plum Island Animal Disease Center; Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN (United States)

African swine fever (ASF) is an important disease in swine currently producing a pandemic affecting pig production worldwide. Except in Vietnam, where two vaccines were recently approved for controlled use in the field, no vaccine is commercially available for disease control. Up to now, the most effective vaccines developed are based on the use of live-attenuated viruses. Most of these promising vaccine candidates were developed by deleting virus genes involved in the process of viral pathogenesis and disease production. Therefore, these vaccine candidates were developed via the genomic modification of parental virus field strains, producing recombinant viruses and reducing or eliminating their residual virulence. In this scenario, it is critical to confirm the absence of any residual virulence in the vaccine candidate. This report describes the assessment of the presence of residual virulence in the ASFV vaccine candidate ASFV-G-ΔI177L in clinical studies conducted under high virus loads and long-term observation periods. The results demonstrated that domestic pigs intramuscularly inoculated with 10⁶ HAD₅₀ of ASFV-G-ΔI177L did not show the presence of any clinical sign associated with ASF when observed daily either 90 or 180 days after vaccination. In addition, necropsies conducted at the end of the experiment confirmed the absence of macroscopic internal lesions associated with the disease. These results corroborate the safety of using ASFV-G-ΔI177L as a vaccine candidate.

• Research Organization: Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC); USDA
• Grant/Contract Number: SC0014664
• OSTI ID: 2471316
• Journal Information: Pathogens, Journal Name: Pathogens Journal Issue: 6 Vol. 12; ISSN 2076-0817; ISSN PATHCD
• Publisher: MDPICopyright Statement
• Country of Publication: United States
• Language: English