Extended Data Fig. 3: CHIKV infectivity in CHO-K1 and CHO-745 cells in the presence or absence of ectopic Mxra8 expression.

a, Surface expression of Mxra8 on CHO-K1 (wild type) and CHO-745 (glycosaminoglycan deficient¹⁵) cells stably transduced with control (vector-only) or mouse Mxra8 as judged by flow cytometry. b, Confirmation of heparan sulfate expression on the surface of CHO-K1 (wild type) and CHO-745 cells. Surface expression of heparan sulfate was evaluated using the R17 protein of rodent herpesvirus Peru, which binds to glycosaminoglycans on the surface of cells³⁹. R17^GAG2 is a mutant form of the protein that lacks binding to glycosaminoglycans and served as a negative control. In a and b, data are representative of two experiments. c, CHO-K1 (wild type) and CHO-745 cells were transduced stably with control (vector) or mouse Mxra8 and inoculated with CHIKV (strains 181/25, AF15561 or LR-2006) and processed for intracellular E2 protein staining by flow cytometry. Data are from three experiments: mean ± s.d. (n = 6, one-way ANOVA with a Dunnett’s multiple comparison test). ****P < 0.001.