Figure 1.

Clinical disease in CD-1 mice infected IC with different CHIKV strains at various ages. (A) Mortality was measured daily in CD-1 pups infected at 2, 7, 14, and 28 days postnatal (PN) with CHIKV strains SL15649 (left), AF15661 (center), and SM2013 (right); n = 12−15 mice per infection group per age at infection. (B) Body weights were measured at 0, 7, and 14 DPI in mice infected at PN2 (left), PN7 (center), and PN14 (right), shown as percent of group’s average 0 DPI weight; dotted line represents initial starting weight; solid horizontal line represents data mean; * p < 0.05, **** p < 0.0001, Sidak’s (PN2, PN7) or Dunnett’s (PN14) multiple comparisons test. (C) Body weights were measured daily in mice infected at PN28, shown as percent of each mouse’s initial body weight at infection; n = 8 mice per group; dotted line represents initial starting weight; data presented as mean ±SEM; # p < 0.05 for PBS vs. SL15649, Dunnett’s multiple comparisons test. (D) Clinical scores were recorded daily for mice infected at PN28 with SL15649 (left), AF15561 (center), and SM2013 (right); n = 8 mice per group; 0 = no clinical signs, 1 = mild abnormal gait and tail posture, 2 = hunched posture, abnormal gait, unkempt hair coat, 3 = marked hunched posture, ataxia, and decreased ambulation (humane endpoint), 4 = moribund/dead/euthanized.