The hemaglutinin (HA) epitope tag was inserted using CRISPR/Cas9 through homologous recombination. The nine amino acid HA epitope was placed between C. remanei (EM464) MSS-1 residues 22 and 23, one residue downstream of the predicted mature N-terminus after signal peptide cleavage. NOTE: nm74 was originally described as nmIs9. Derived from parental strain SB146. Reference: Yin D, et al. Science. 2018 Jan 5;359(6371):55-61.