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. 2021 Apr 27;13(5):765.
doi: 10.3390/v13050765.

ASFV-G-∆I177L as an Effective Oral Nasal Vaccine against the Eurasia Strain of Africa Swine Fever

Manuel V Borca  1 , Elizabeth Ramirez-Medina  1 , Ediane Silva  1   2 , Elizabeth Vuono  1   3 , Ayushi Rai  1   4 , Sarah Pruitt  1 , Nallely Espinoza  1 , Lauro Velazquez-Salinas  1   2 , Cyril G Gay  5 , Douglas P Gladue  1
Affiliations

ASFV-G-∆I177L as an Effective Oral Nasal Vaccine against the Eurasia Strain of Africa Swine Fever

Manuel V Borca et al. Viruses. .

Abstract

The African swine fever virus (ASFV) is currently causing a pandemic affecting wild and domestic swine from Western Europe to Asia. No commercial vaccines are available to prevent African swine fever (ASF), resulting in overwhelming economic losses to the swine industry. We recently developed a recombinant vaccine candidate, ASFVG-ΔI177L, by deleting the I177L gene from the genome of the highly virulent ASFV strain Georgia (ASFV-G). ASFV-G-ΔI177L has been proven safe and highly efficacious in challenge studies using parental ASFV-G. Here, we present data demonstrating that ASFV-G-ΔI177L can be administered by the oronasal (ON) route to achieve a similar efficacy to that of intramuscular (IM) administration. Animals receiving ON ASFV-G-ΔI177L were completely protected against virulent ASFV-G challenge. As previously described, similar results were obtained when ASFV-G-ΔI177L was given intramuscularly. Interestingly, viremias induced in animals inoculated oronasally were lower than those measured in IM-inoculated animals. ASFV-specific antibody responses, mediated by IgG1, IgG2 and IgM, do not differ in animals inoculated by the ON route from that had IM inoculations. Therefore, the ASFV-G-ΔI177L vaccine candidate can be administered oronasally, a critical attribute for potential vaccination of wild swine populations.

Keywords: ASF; ASFV; African swine fever; African swine fever virus; I177L; swine; vaccine.

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Conflict of interest statement

The authors Douglas Gladue and Manuel Borca have a patent filed for ASFV-G-ΔI177L as an effective vaccine against ASF. No other authors have a conflict of interest.

Figures

Figure 1
Figure 1
Kinetics of body temperature values in pigs oronasally (A) or intramuscularly (B) inoculated with ASFV-G-ΔI177L before (Days post-infection) and after challenge (Days post-challenge) with ASFV-G. Each curve represents individual data from each of the animals under each of the treatments. Red curves represent a group of mock-inoculated animals used as a control during both challenge experiments.
Figure 2
Figure 2
Viremia titers in pigs either oronasally or intramuscularly inoculated with ASFV-G-ΔI177L before and after challenge with ASFV-G (A,B). Each curve represents individual data from each of the animals under each of the treatments. Red curves represent mock-inoculated animals used as controls during the challenge. The sensitivity of virus detection was ≥1.8 log10 HAD50/mL.
Figure 3
Figure 3
Evolution of mortality in pigs either oronasally or intramuscularly inoculated with ASFV-G-ΔI177L or mock treated and challenged with 102 HAD50 of ASFV-G.
Figure 4
Figure 4
Anti-ASFV antibody titers detected by ELISA in pigs oronasally (ON) or intramuscularly (IM) inoculated with ASFV-G-ΔI177L. Individual serum ASFV-specific antibody titers (indicated by individual symbols) mediated by IgM, total IgG, IgG1 and IgG2 are represented in panels (A), (B), (C) and (D), respectively. Titers are expressed as the log10 of the reciprocal of the highest dilution of sera at least duplicating OD readings of a pool of mock-infected sera.
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