CD4 T cells are responsible for the intensified joint pathology at 6 d postinfection. CD4 T cells are responsible for the intensified joint pathology at 6 d postinfection. CD4 T cell–depleted or IgG control mice were infected with 1 × 106 pfu CHIKV by ventral footpad inoculation at day 0 and monitored daily until 14 d postinfection (dpi). (A) Disease score of WT and Viperin−/− mice with (αCD4) or without (IgG) CD4 T-cell depletion calculated as the increase in footpad height × breadth relative to day 0. (B) CHIKV-specific IgG titers at day 14 dpi assessed by virion-based ELISA. (C) CHIKV neutralization capacity of individual serum samples at 14 dpi at a 1:1,000 dilution. (D) CHIKV neutralization capacity of serially diluted individual serums of non-CD4 T cell–depleted (IgG) mice. The data are representative of two independent experiments (n = 8–9 mice per group). Nonparametric Mann–Whitney t test was performed for each day between the groups indicated on the figure legend by the bar, and the significance is indicated on the figure by the * color (*P < 0.05, **P < 0.01, and ***P < 0.001). Guillaume Carissimo et al. LSA 2019;2:e201900298 © 2019 Carissimo et al.