New foot-and-mouth disease vaccine, O JC-R, induce complete protection to pigs against SEA topotype viruses occurred in South Korea, 2014–2015

Figures

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  Fig. 1. Characterization of a type O FMD vaccine strain, O JC-R virus. (A) Schematic diagram of the type O JC-R FMDV genome; the 3B1B2 replacement was performed by using the method given by Ko et al. [11] and the 142 residue (C142T) in the 3C region was mutated. (B) Electron microscopy of the FMDV vaccine strain, O JC-R. The bar represents 100 nm. (C) Pathogenesis of O JC-R and O JC wild-type (O/Jincheon/SKR/2014) or mutated viruses in 7-days-old mice. (D) No detection of the NSP antigen in virus cultured supernatant when using the FMDV antigen rapid kit (PBM, USA) for differentiation between vaccine and wild-type virus using the previous method [11]. C, control line; SP, FMDV structural protein line; NSP, FMDV non-structural protein line; FMD, foot-and-mouth disease; FMDV, foot-and-mouth disease virus.

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  Fig. 2. Survival and weight loss in vaccinated adult C57BL/6 mice after homologous or heterologous challenge after vaccination. The mice were vaccinated with the 1/10 to 1/640 doses (diluted to 1 dose for cattle and pigs). (A) Survival rate in O JC-R-vaccinated adult C57BL/6 mice (n = 5) after the O/Jincheon/SKR/2014 challenge at 21 DPV. (B) Body weight in O JC-R-vaccinated adult C57BL/6 mice (n = 5) after the O/Jincheon/SKR/2014 challenge at 21 DPV, (C) Survival rate in O JC-R-vaccinated adult C57BL/6 mice (n = 5) after the O Vet 2013 challenge at 21 DPV, (D) Body weight in O JC-R-vaccinated adult C57BL/6 mice (n = 5) after the O Vet 2013 challenge at 21 DPV, (E) Survival rate in O JC-R-vaccinated adult C57BL/6 mice (n = 5) after the O/Jincheon/SKR/2014 challenge at 7 DPV. (F) Body weight in O JC-R-vaccinated adult C57BL/6 mice (n = 5) after the O/Jincheon/SKR/2014 challenge at 7 DPV. dpc, days post challenge; DPV, days post vaccination.

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  Fig. 3. Clinical scores, viremia, and virus shedding in O JC-R-immunized pigs after the O/Jincheon/SKR/2014 virus challenge. (A) Virus-neutralizing antibody titers in immunized pigs for the virus challenge. The O/Jincheon/SKR/2014 virus challenge was attempted at 28 days post challenge. (B) Clinical scores and virus detection in sera and oral swabs for the negative group (n = 2, #3–6, #4–5) and vaccinated group (n = 4, #JC-1, #JC-3, #JC-5, #JC-6). DPI, days post-infection.

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  Fig. 4. Antibody titers in pigs vaccinated with the experimental foot-and-mouth disease vaccine, O JC-R. (A) Type O SP-ELISA results. (B) VN titers against O/Jincheon/SKR/2014. (C) VN titers against O/Boeun/SKR/2017. (D) VN titers against O Taiwan97. The dotted lines in SP-ELISA results indicate 50% inhibition, which is the positive cut-off in the test. The dotted lines in the VN test show 1.5 log VN titers (1:32). The arrows indicate the challenge time at 28 DPV. ELISA, enzyme-linked immunosorbent assay; SEA, Southeast Asia; ME-SA, Middle East–South Asia; VN, virus-neutralizing; DPV, days post challenge; DPI, days post-infection. *p < 0.05; †p < 0.01; ‡p < 0.001.