RecipharmCobra Biologics granted Xer-cise patents

Published: 3-Feb-2011

Technology enables bacteria to be genetically modified

RecipharmCobra Biologics, ReciPharm’s specialist biologics process development and cGMP manufacturing division, has been granted European patents on its Xer-cise genetic engineering technology.

Xer-cise enables bacteria to be genetically modified without leaving antibiotic resistance genes on their chromosomes. The company said this overcomes the problems caused by the biosafety risk of potentially spreading antibiotic resistance to pathogens, the limited number of available antibiotic resistance genes and the competing use of these genes on plasmids. Xer-cise uses Xer recombinases, which are naturally present in virtually every bacterial species.

Genetic modification is achieved by inserting a DNA cassette containing an antibiotic resistance gene, so that modified bacteria can be identified by their ability to survive in the presence of the antibiotic. By placing the sites recognised by Xer recombinases (dif sites) either side of the antibiotic resistance gene, the recombinases excise the gene when cells are grown later with no antibiotic present. Xer-cise has been demonstrated in bacteria including Escherichia coli, Salmonella, Bacillus subtilis and Mycobacterium, and is applicable to many other bacteria.

Simon Saxby, vp of Biologics at RecipharmCobra Biologics, said: ‘Xer-cise has enabled molecular biologists at RecipharmCobra and elsewhere rapidly to construct bacterial strains that are not antibiotic resistant, and are therefore advantageous for the commercial production and delivery of biologics. We anticipate that this technology will greatly simplify and accelerate the genetic modification of many species of bacteria.’

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