Fig. 2

Co-infection delays virus resolution in tissues and suppress acute CHIKV-induced joint pathology. Tissue viral load in a the whole body and b the joints of CHIKV (n = 5) and CHIKV + PbA (n = 6) groups. Follow-up was terminated at 22 dpi as co-infected mice died of hyper-parasitaemia between 23 and 26 dpi. c Footpad viral RNA load on 2 dpi in the joints of CHIKV (n = 5) and CHIKV + PbA (n = 5) groups. Tissue viral load in d the whole body and e the joints of CHIKV (n = 7) and Py17x (−4 dpi) + CHIKV (n = 5) groups. f Footpad viral RNA load on 2 dpi in the joints of CHIKV (n = 5) and Py17x (−4 dpi) + CHIKV (n = 4) groups. g Footpad viral load of CHIKV (n = 6) and Py17x (−4 dpi) + CHIKV (n = 7) groups at 20 dpi, 30 dpi, 40 dpi and 45 dpi. Bioluminescence signal from the luciferase-tagged virus in both groups fell below the detection limit at 45 dpi. Representative pseudo-color images of bioluminescence signal at 20 dpi, 30 dpi, 40 dpi and 45 dpi are shown. Histopathological scoring of (h) oedema in the subcutaneous region and (i) muscle necrosis in the joints of CHIKV, CHIKV + PbA and Py17x (−4 dpi) + CHIKV (n ≥ 4 per group) at 6 dpi. j Total CD45 + cellular infiltration (flow cytometry) and infiltration of inflammatory cells in different regions of the joint (histological grading) of CHIKV, CHIKV + PbA and Py17x (−4 dpi) + CHIKV (n ≥ 4 per group) at 6 dpi. Data in a–g were analyzed by Mann-Whitney two-tailed test and h–j by one-way ANOVA with Tukey post hoc test (*P < 0.05, **P < 0.01 and ***P < 0.001). Data represent the means ± SD. Abbreviations: CHIKV, Chikungunya virus; CoIF, co-infected; dpi, days post infection; PbA, Plasmodium berghei-ANKA; Py17x, Plasmodium yoelii 17×