Longitudinal serology for endemic and non-endemic patients.

(A) Phylogenetic tree produced using the E1, 6k, and E2 amino acid sequences for the six alphaviruses under investigation; viruses are color coded to match serology graphs. (B, C) Sera samples from each subject were tested for neutralization activity against CHIKV, ONNV, RRV, MAYV, Una, and VEEV by plaque reduction neutralization titer assays (PRNT) performed on confluent monolayers of Vero cells. Shown are the average 50% reduction titer values (PRNT₅₀) calculated by variable slope non-linear regression using Prism software. Longitudinal serology is shown for 9/12 human subjects. Additional samples for the other human subjects were unavailable. Endemic subject serologic profiles are shown in (B). Serology for non-endemic subjects is shown in (C). (D) Summarizes the breadth of cross-neutralization data for both endemic and non-endemic subjects at all time points presented in (B) and (C). The statistical analysis to compare grouped cross-neutralizing PRNT₅₀ values to CHIKV PRNT₅₀ was completed using an ANOVA and Friedman’s test ***p = 0.0001, **** p = <0.0001. Limit of detection (LOD) is 40, samples below the LOD were assigned an arbitrary value of 39.