Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus responsible for the first autochthonous Italian outbreak in 2007. A226V mutation in E1 has been associated with enhanced replication in A. albopictus vector. Possible involvement of this mutation in enhanced infection capability in primate cells and sensitivity to exogenous interferon (IFN)-a was investigated. No significant differences were observed between the two isolates in terms of replication kinetic, virus yield and cytopathic effect (CPE). Interestingly, the A226V-carrying strain was more susceptible to the antiviral action of recombinant IFN-a. The interplay between A226V mutation and innate defence mechanisms needs further investigation.