This self-amplifying mRNA encodes four nonstructural proteins (nsP1 to nsP4) derived from a positive-stranded alphavirus venezuelan equine encephalitis virus (VEEV), and NLS-eCas9.
NLS-eCas9 is a mutant of Streptococcus pyogenes SF370 Cas9 protein with nuclear localization signal (NLS) at both N and C terminus. The mutant Cas9 reduces off-target effects by more than 10 folds.