(Cell 176, 281–294.e1–e19; January 10, 2019) The authors were recently alerted to a typographical error in the sequence of the modified NP construct “NP(FlAsH),” included in the file Data S1. The sequence as originally published in this file incorrectly excludes a 20-nucleotide sequence at the end of the NP coding region and contains two substitutions in the initial non-coding region. As verified by sequencing, these deletions and substitutions are not present in the construct used throughout the work. In particular, the deletion would have disrupted the C-terminus of NP and removed the tetracysteine tag if it had been present. The partial sequence for NP(FlAsH) shown in Figure S1A for this same construct is correct as published. The online version of Data S1 has now been corrected, giving the correct sequence for NP(FlAsH). This error does not affect the results in the paper or the interpretation of the data, and we apologize for any confusion this error has caused.