Chikungunya Virus is a mosquito-borne positive-sense RNA virus with limited treatment options and global health implications. nsP1 is a replication complex coordinator and is responsible for capping viral RNA, however the role of the C-terminal intrinsically disordered region (IDR) is unclear. Alanine scanning mutagenesis was used to identify essential residues in the C-Terminal IDR of nsP1. Mutants at conserved residues were introduced into live virus to determine their effects on replication.