Figure 5
Histology images of mouse tarsal joints indicate disease severity. Mice were infected with CHIKV and treated with IL2-based treatments on days 16–18 post-infection, and tarsal joints were dissected 19 days post-infection. (a) Healthy tarsal joint from an uninfected mouse illustrating the synovium (S), joint space (JS), articular cartilage (AC), and subchondral bone (B)3; (b) CHIKV + mouse tarsal joint with bone and articular cartilage erosion (arrow), active synovitis (solid arrowhead), and pannus with articular cartilage erosion (open arrowhead); (c) CHIKV + mouse tarsal joint with mild myositis with degenerative myocytes (arrowhead), fasciitis (arrow), and periostitis with cortical bone erosion; and (d) CHIKV + mouse tarsal joint with severe myositis with degeneration and necrosis (arrows). (e) Composite joint pathology scores for each mouse by treatment group. Male mice are denoted by circles, and females by triangles. Scores for each mouse were calculated by adding the scores from each histological component. A score of 0 to < 4 was considered low severity, 4 to < 7 was moderate, and > 7 was severe, as illustrated by the horizontal dotted lines.
