Figure 5

Exacerbation of joint inflammation in adult mice. (a,b) Three-weeks old, C57BL/6 WT female mice (n = 5 animals per group) were infected via footpad inoculation with 10⁶ PFU of CHIKV. Immediately, these mice were administered intraperitoneally with ~2 µg/ml (total IgG concentration) mice sera from CHIKV-infected mice (enhanced) or PBS (non-enhanced). Daily assessment of (a) viremia and (b) disease score were performed. All Data are presented as mean ± SD by Mann-Whitney U test (*P = 0.0278, *P = 0.0159, *P = 0.0159 and *P = 0.0297 for 2, 3, 4 and 5 dpi viremia respectively; **P = 0.0040, **P = 0.0079, **P = 0.0060, **P = 0.0079, **P = 0.0079, *P = 0.0104, *P = 0.0172, **P = 0.0040, **P = 0.0060, *P = 0.0106 and *P = 0.0106 for 3, 4, 5, 6, 7, 8, 9, 10, 11, 13 and 14 dpi disease score respectively). Immune-phenotyping was performed for (c) footpad and (d) popliteal lymph node on 6 dpi. Results are displayed as number of neutrophils, CD4+ T cells and monocytes per organ from 4 to 10 animals per group. (e) Total RNA was extracted from the joint footpads of infected mice (n = 5 to 10 animals per group) and qRT-PCR was performed to detect for the expression of crucial immune genes. Gene expression data are expressed as fold expression relative to the mock-infected mice. Mice sacrificed for immune-phenotyping and gene expression studies were infected as described for (a,b). All Data are presented as mean ± SD by Mann-Whitney U test (*P = 0.0186, *P = 0.0326 and *P = 0.0185 for neutrophils, monocytes and CD4+ T cells infiltration into respective organs; *P = 0.0276, *P = 0.0376 and *P = 0.0376 for IFNγ, DEF14 and IL-10 expression respectively).