Evaluation of Vaccine Strains Developed for Efficient, Broad-Range Protection against Foot-and-Mouth Disease Type O

Figures

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  Figure 1. Schematic diagram of FMDV genomes with VP1 replacement for the development of a broad-spectrum vaccine strain. (A) JC-VP1, which has the P1 genome of O1 Manisa (VP4, 2, 3) and O/SKR/Jincheon/2014 (VP1), and (B) PA2-VP1, which has the P1 genome of O1 Manisa (VP4, 2, 3) and O PA2, O PAK/44/2008 (VP1). The 3B mutation of the 3B region was obtained using the same methods used in a previous report.

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  Figure 2. Antibody responses of cattle and pigs vaccinated with either JC-VP1 or PA2-VP1. Schematic diagram of study strategy (A). Neutralizing antibody titers and SP ELISA in cattle vaccinated with JC-VP1 (B) and PA2-VP1 (C). Cattle were inoculated with a single dose (15 μg/dose of inactivated antigen mixed with ISA 206, saponin, and aluminum hydroxide gel adjuvant). Neutralizing antibody titers and SP ELISA in pigs vaccinated with JC-VP1 (D) and PA2-VP1 (E). Percent inhibition (PI) > 50 was considered the cutoff of a positive reaction (blue dashed line). VN titers (log10) > 1.65 were regarded as positive (red dashed line). The pigs were inoculated with a second vaccination (15 μg/dose of inactivated antigen mixed with ISA 206, saponin, and aluminum hydroxide gel adjuvant) at 28 dpv. Comparative analysis of JC-VP1 and PA2-VP1 in vaccinated cattle and pigs (F). Statistical analyses were performed ANOVA and t test. * p < 0.05.

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  Figure 3. Variation in neutralizing antibody titers in pigs immunized with experimental vaccines. The pigs were inoculated with a second vaccination (15 μg/dose of inactivated antigen mixed with ISA 206, saponin, and aluminum hydroxide gel adjuvant) at 28 dpv. Schematic diagram of study strategy (A). The pigs were challenged with the virus of SEA (O-JC) topotype (B), ME-SA (O-BE) topotype (C), and Cathay (O-TWN) topotype (D) after vaccination with either JC-VP1 or PA2-VP1. In the case of PA2-VP1, different doses of 15 μg or 20 μg against the SEA topotype virus were evaluated. In the case of JC-VP1, different doses of 15 μg or 20 μg against the ME-SA topotype virus were evaluated.

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  Figure 4. Protection in immunized pigs challenged with the viruses of the three different topotypes after vaccination with JC-VP1 or PA2-VP1. The negative control groups (#1-1, #1-2, #1-3) and vaccinated group with JC-VP1 or PA2-VP1 (#2-1, #2-2, #2-3, #2-4, #3-1, #3-2, #3-3, #3-4 were tested using a 15 μg inactivated antigen vaccine and #2-5, #2- 6, #2-7, #2-8, #3-5, #3-6, #3-7, #3-8 were tested using a 20 μg inactivated antigen vaccine) were challenged with SEA (A), ME-SA (B), and Cathay (C). Clinical scores (black bar), viremia (red, serum; blue, oral swab) were evaluated up to 8 days post-challenge. The JC-VP1-vaccinated groups were challenged with the viruses of the three different topotypes. Complete protection against SEA and Cathay was confirmed when the pigs were vaccinated with 15 μg of inactivated antigen vaccine of JC-VP1, but only 50% protection against ME-SA was confirmed. Complete protection against ME-SA was confirmed when tested using 20 μg of inactivated antigen vaccine of JC-VP1. The PA2-VP1-vaccinated groups were challenged with the viruses of the three different topotypes. Complete protection against the three topotype viruses was confirmed when the pigs were vaccinated…