(B) Half maximum inhibitory concentration (IC50) of pooled sera collected on 90 dpv were characterized in HEK293T cells infected with WT-CHIKV (MOI 5). Sera were serially diluted at 1:625000, 1:125000, 1:25000, 1:16000, 1:8000, 1:5000, 1:4000, 1:2000, 1:1000, 1:500, 1:250. Sera dilution to obtain IC50 are shown in parenthesis. 