<i>In vivo</i> selection of viruses resistant to MAb neutralization.

aIn vivo selection for resistant virus was performed by administering the indicated individual or combinations of MAbs before (−24 hours) or after (+24 or 48 hours) CHIKV-LR infection. Resistant virus was isolated directly from tissues (leg and brain), and cDNA was prepared by reverse transcription and sequenced. The change in neutralizing activity of the bulk virus recovered from tissue is highlighted by the differences in EC50 values.