Improved shuttle vectors for Francisella tularensis genetics


  • Editor: Stefan Schwarz

Correspondence: Martin S. Pavelka Jr, Department of Microbiology and Immunology, University of Rochester Medical Center, 601 Elmwood Avenue, PO Box 672, Rochester, NY 14642, USA. Tel.: +1 585 275 4670; fax: +1 585 473 9573; e-mail:


We previously described the construction and characterization of Escherichia coli–Francisella tularensis shuttle vectors, derived from the cryptic Francisella plasmid pFNL10, for the genetic manipulation of F. tularensis ssp. tularensis. We now report further characterization of the biology of these shuttle vectors and the development of a new generation of Francisella plasmids. We show that the addition of ORF3 from pFNL10 can convert an unstable shuttle vector into a stable one, and that this is likely due to increased plasmid copy number. We also describe various improvements to the earlier generations of shuttle vectors, such as the addition of a multiple cloning site containing a novel RsrII restriction endonuclease site for directional insertion of Francisella genes, and the inclusion of the F. tularensis blaB promoter for heterologous gene expression.