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).