Development of a Potent Stabilizer for Long-Term Storage of Foot-and-Mouth Disease Vaccine Antigens

Figures

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  Figure 1. Characteristic thermal instability of foot-and-mouth disease virus (FMDV) O SKR/JC/2014. FMDV O SKR/JC/2014 (O JC), O SKR/BE/2017 (O BE), A SKR/YC/2017 (A YC), and Asia 1 Shamir/ISR/1989 (As 1 Shamir) were heated at 45 °C and their 146S antigen recovery (%) was calculated at each time point (1, 2, 5, 15, and 30 min) based on the antigen quantity measured by sucrose density gradient fractionation. **, p < 0.01.

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  Figure 2. Effectivity of buffers for short-term storage of FMDV O JC vaccine antigen. (a) The 146S particle recovery (%) in each buffer during 4-week storage at 4 °C; (b) The 146S particle recovery (%) in each buffer during 4-week storage at −70 °C. The dotted line is set at 90% recovery. *, p < 0.05, **, p < 0.01. Different lowercase letters indicate significant differences at p < 0.05; (c) Microscopic observation of 146S particles stored in the aqueous phase; (d) Microscopic observation of 146S particles stored in frozen phase. Scale bar = 100 μm. Arrowheads indicate degrading particles. Abbreviations: TBS, Tris-buffered saline (pH 7.6); PBS, phosphate-buffered saline (pH 7.6); PNM, PBS supplemented with NaCl and MgCl2 (pH 7.6); TNE, TBS supplemented with ethylenediaminetetraacetic acid (pH 7.6); TK, Tris-KCl buffer (pH 7.6); KP, potassium phosphate buffer (pH 7.6).

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  Figure 3. Effectivity of buffers for long-term storage of FMDV O JC vaccine antigen. (a) The 146S particle recovery (%) in each buffer during 1-year storage at 4 °C; (b) The 146S particle recovery (%) in each buffer during 1-year storage at −70 °C. The dotted line is set at 90% recovery. *, p < 0.05, **, p < 0.01. Different lowercase letters indicate significant differences at p < 0.05.

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  Figure 4. Effectivity of excipients for long-term storage of FMDV O JC vaccine antigen. (a) The 146S particle recovery (%) in each buffer during 1-year storage at 4 °C; (b) The 146S particle recovery (%) in each buffer during 1-year storage at −70 °C. The dotted line is set at 90% recovery. *, p < 0.05, **, p < 0.01. Different lowercase letters indicate significant differences at p < 0.05. Abbreviations: TK, Tris-KCl buffer (pH 7.6); Suc, 20% sucrose; SLA, 10% sucrose with 5% lactalbumin hydrolysate.

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  Figure 5. Compatibility of the candidate stabilizer composition with other FMDV strains. Relative recovery (%) was calculated from the remaining content of the 146S antigen after heating at 50 °C for 30 min when the antigen content of SLA in TK is set as 100%. Different lowercase letters indicate significant differences at p < 0.05. Abbreviations: O BE, O SKR/BE/2017; A YC, A SKR/YC/2017; As 1 Shamir, Asia 1 Shamir/ISR/1989; TBS, Tris-buffered saline (pH 7.6); TK, Tris-KCl buffer (pH 7.6); SLA, 10% sucrose with 5% lactalbumin hydrolysate.