Figure 1. NTC antibiotic-free selection vectors. (A) NTC8485-O2-gD2 vector map; (B) Left: In a plasmid-free cell, levansucrase is expressed from a chromosomally integrated SacB gene, leading to cell death in the presence of sucrose. Right: RNA-OUT from the plasmid represses translation of the SacB gene, achieving plasmid selection.