A dual-gene-deleted ASFV Lv17/WB/Rie1-ΔCD candidate administered orally to wild boar confers DIVA-compatible protection against virulent challenge

African swine fever (ASF) continues to expand worldwide. Recent detection in wild boar in Spain highlights the urgent need for effective control tools, with oral vaccination as a key priority. Following previous evaluation of the attenuated Lv17/WB/Rie1 strain, we assess an improved derivative, Lv17/WB/Rie1-ΔCD, lacking EP402R (CD2v) and EP153R, replaced by GFP to abrogate haemadsorption and enable Differentiating-Infected-from-Vaccinated-Animals (DIVA) diagnostics. Vaccinated animals received either a single high dose (10<sup>4</sup> TCID₅₀) or a prime and re-exposure regimen (10<sup>2</sup> TCID₅₀ plus a 10<sup>4</sup> TCID₅₀). Animals were challenged intramuscularly with the virulent Armenia07 genotype II strain. The ΔCD vaccine was well tolerated, inducing only transient low-grade fever. Prime-re-exposure vaccination induced earlier seroconversion (mean 12 ± 4 dpv) and sterilizing immunity in 5/6 animals in the high dose group. Overall protection reached 90%, while all unvaccinated controls died within 7 days. Quantitative PCR revealed >10³-fold reductions in viral genome copies in blood and tissues versus controls. DIVA ELISA reliably distinguished vaccine-induced antibodies from infection-derived responses. These findings identify Lv17/WB/Rie1-ΔCD as a safer oral ASFV vaccine candidate, addressing concerns raised with the parental Lv17/WB/Rie1 by increasing attenuation and supporting multi-gene deletion strategies. Further studies on safety, transmission, genetic stability, and environmental behaviour are required before large-scale field trials.

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Publication Details

Journal
Veterinary Quarterly
Published
2026-03-26
DOI
https://doi.org/10.1080/01652176.2026.2649573
Primary Topic
Animal Disease Management and Epidemiology
Type
article
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article

A dual-gene-deleted ASFV Lv17/WB/Rie1-ΔCD candidate administered orally to wild boar confers DIVA-compatible protection against virulent challenge

José Á. Barasona, Marta Díaz-Frutos, Paola Nicolussi, Giulia Franzoni et al.
Veterinary Quarterly
Animal Disease Management and Epidemiology
article

A dual-gene-deleted ASFV Lv17/WB/Rie1-ΔCD candidate administered orally to wild boar confers DIVA-compatible protection against virulent challenge

José Á. Barasona, Marta Díaz-Frutos, Paola Nicolussi, Giulia Franzoni, Aleksandra Kosowska, Gabriela González-García, Daniel De Antonio-Gómez, Mónica Sánchez-Segovia, Néstor Porras, Sandra Barroso-Arévalo, Paloma Rueda
article en

Abstract

African swine fever (ASF) continues to expand worldwide. Recent detection in wild boar in Spain highlights the urgent need for effective control tools, with oral vaccination as a key priority. Following previous evaluation of the attenuated Lv17/WB/Rie1 strain, we assess an improved derivative, Lv17/WB/Rie1-ΔCD, lacking EP402R (CD2v) and EP153R, replaced by GFP to abrogate haemadsorption and enable Differentiating-Infected-from-Vaccinated-Animals (DIVA) diagnostics. Vaccinated animals received either a single high dose (10<sup>4</sup> TCID₅₀) or a prime and re-exposure regimen (10<sup>2</sup> TCID₅₀ plus a 10<sup>4</sup> TCID₅₀). Animals were challenged intramuscularly with the virulent Armenia07 genotype II strain. The ΔCD vaccine was well tolerated, inducing only transient low-grade fever. Prime-re-exposure vaccination induced earlier seroconversion (mean 12 ± 4 dpv) and sterilizing immunity in 5/6 animals in the high dose group. Overall protection reached 90%, while all unvaccinated controls died within 7 days. Quantitative PCR revealed >10³-fold reductions in viral genome copies in blood and tissues versus controls. DIVA ELISA reliably distinguished vaccine-induced antibodies from infection-derived responses. These findings identify Lv17/WB/Rie1-ΔCD as a safer oral ASFV vaccine candidate, addressing concerns raised with the parental Lv17/WB/Rie1 by increasing attenuation and supporting multi-gene deletion strategies. Further studies on safety, transmission, genetic stability, and environmental behaviour are required before large-scale field trials.

Veterinary QuarterlyVol. 46(1)
Universidad Complutense de Madrid (ES), Standard Bio (Norway) (NO), Department of Animal Health (VN), Istituto Zooprofilattico Sperimentale della Sardegna (IT)
Life in Land
Openalex Percentile: Top 3%
Animal Disease Management and Epidemiology
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