Anti-FMDV activity of IRES-specific pmiR242 + 276 in suckling mice. Animals (4 suckling mice of each group) were challenged by subcutaneous injection with mixtures of the miRNA expression plasmid pmiR242 + 276 and the indicated (50 LD50, 100 LD50) FMDV O/HN/CHA/93 (A), AF72 (B), Asia 1/Jiangsu/China/2005 (C), O/Tibet/China/1/99 (D), and O/CHN/Mya98/33-P (E), respectively. Mice were treated with 1 × PBS as negative control and the same titers of the selected FMDVs as positive control. All suckling mice were continuously observed for one week after virus challenge. Kaplan-Meier survival curves were analyzed by the log rank test using GraphPad Prism version 5.01 (GraphPad software, San Diego, CA).