(A) Ultrasonic vocalization (USV) assay. At P9, pups from the indicated experimental groups were separated from their mothers to elicit USV calls. The number of pup calls is plotted on the y-axis (n = 25 (PBS, Cont), n = 28 (PBS, anti-IL-17a), n = 38 (Poly(l:C), Cont), n = 34 (Poly(l:C), anti-IL-17a); from 6–7 independent experiments. (B) Social approach behavior. Graphed as a social preference index (% time spent investigating social or inanimate stimulus out of total object investigation time) (n = 15 (PBS, Cont), n = 15 (PBS, anti-IL-17a), n = 16 (Poly(l:C), Cont), n = 20 (Poly(l:C), anti-IL-17a); from 6–7 independent experiments. (C) Marble burying behavior. Percentage of the number of buried marbles is plotted on the y-axis (n = 15 (PBS, Cont), n = 15 (PBS, anti-IL-17a), n = 15 (Poly(l:C), Cont), n = 20 (Poly(l:C), anti-IL-17a); from 6–7 independent experiments. (D) Total distance traveled during social approach behavior. (A, C and D) One-way ANOVA with Tukey post-hoc tests. (B) Two-way ANOVA with Tukey post-hoc tests. **P < 0.01 and *P < 0.05. Graphs show mean ± SEM.