The system, known as oriSelect, uses a modified E.coli strain that only grows in the presence of plasmids containing the “origin of replication” pMB1 gene, eliminating the need to include additional genes to act as selection markers.
This means the oriSelect plasmids are smaller, and therefore more stably replicated during cell division, than those used in other systems that require some form of maker gene to identify successfully transfected clones.
A company spokesman told Outsouring-pharma that this will benefit manufacturing efficiency and yields, explaining that: “A smaller plasmid means more molecules per gramme.”
“For recombinant protein expression, there will theoretically be an increase due to the absence of an additional expressed gene, the antibiotic resistance gene, so we will test this when the final production strains are constructed.
He added that oriSelect “could replace any conventional antibiotic-selected DNA or protein expression system in E. coli,” and suggested its main will be contract manufacturing projects where the absence of antibiotics is critical.
The additional benefit of oriSelect, in common with RecipharmCobra’s other genetic engineering technology platform ORT, is that it removes the risk that antibiotic resistance genes used for selection purposes are passed on to other bacteria.
This point was stressed by company VP Simon Saxby, who said that: “Antibiotic resistance gene transfer is an area of concern where oriSELECT and ORT can provide a state-of-the-art solution.”