FIG 3.

Virulence of CV-A5-M14 and establishment of the Kunming mouse model. CV-A5-M14 is a virulent, mouse-adapted strain that can infect 14-day-old (i.c. and i.p. routes) and 7-day-old (oral) Kunming mice. The criteria of clinical scores of infected Kunming mice are the following: 0, healthy; 1, fatigue or sleepiness; 2, weight loss and hunched back; 3, hindlimb weakness or jitter; 4, limb paralysis; 5, dying or death. The survival rates (percent) (A), mean clinical scores (B), and mean body weights (C) were compared in mice infected with CV-A5-M14 and mock-infected mice via the i.c., i.p. (14-day-old mice), and oral (7-day-old mice) routes at doses of 3 × 10⁷ CCID₅₀, 3 × 10⁸ CCID₅₀, and 3 × 10⁸ CCID₅₀, respectively. (D) The LD₅₀ of CV-A5-M14 was determined through the i.p. route at the doses indicated. The results are presented as the means ± SEM.