FIG 5.

Resistance level of reverse-engineered CHIKV containing mutations selected by passaging CHIKV in the presence of FHNA in the five-step protocol. The graph shows the fold resistance to FHNA (compared to wt CHIKV) of the ten single rCHIKV mutants, five double rCHIKV mutants, and three triple rCHIKV mutants that were reverse engineered. The dashed line represents the cutoff value of 40 (level of resistance caused by the nonspecific *524R mutation) that was used to exclude mutants with a nonspecific resistance to FHNA.