Development of a Chimeric Vaccine Providing Protection Against the Type A ASIA/Sea-97 FMDVs in East Asia

Figures

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  Figure 1. Sequences of the structural proteins (SPs) of the Apo22 and Apo22-GP vaccine strains. The amino acid sequences of the SPs of the vaccine strains are shown alongside those of the incorporated SPs from the A/POC/2010 (VP4, VP2, and VP3) and A22 Iraq (VP1) strains. Yellow box: highlights the amino acid sequence from A/GP/2018 that was inserted into VP1 to create the Apo22-GP strain.

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  Figure 2. Recombinant Apo22 and Apo22-GP strains as FMD vaccine candidates: (a) schematic representation of the structural proteins; (b) electron microscopy images of viral particles. Scale bar: 100 nm.

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  Figure 3. Clinical sign scores, viremia levels, and oral virus shedding in vaccinated and control pigs challenged with A/POC/2010 or A/GP/2018: (a) vaccinated pigs (n = 4) challenged with the A/POC/2010 virus; (b) unvaccinated controls (n = 2) challenged with the A/POC/2010 virus; (c) vaccinated pigs (n = 4) challenged with the A/GP/2018 virus; (d) negative controls (n = 2) challenged with the A/GP/2018 virus. * Temporary body temperature increase. Black bars: clinical signs; blue: oral swab; red: serum samples.

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  Figure 4. Virus-neutralizing-antibody response to wild-type FMDV challenge in Apo22-GP-vaccinated pigs. Sera were collected at multiple points dpc from pigs immunized with Apo22-GP and challenged with either (a) A/POC/2010 (n = 4) or (b) A/GP/2018 (n = 4). Neutralizing-antibody levels were measured against five type A FMDV strains. Titers are expressed as Log10 values; values ≥ 1.6 Log10 (dotted line) were considered positive. Statistical analysis was performed using two-way ANOVA followed by Tukey’s test. * p < 0.05; ** p < 0.01; *** p < 0.001.

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  Figure 5. Immunogenicity of the Apo22-GP vaccine in pigs. Serological responses were assessed in pigs (n = 5) vaccinated with the Apo22-GP candidate. Neutralizing-antibody levels against various type A FMDVs and levels of SP-specific antibodies were quantified. Titers ≥ 1.6 Log10 (dotted line) were considered positive for virus neutralization. SP-specific antibody levels were measured by ELISA, with a threshold of 40% defined as positive. Statistical analysis was performed using two-way ANOVA followed by Tukey’s test. *** p < 0.001.