Abstract: The present invention features gram-positive bacteria resistant to 5-fluorodeoxyuridine (FUdR). Such bacteria will preferably be commensal, and will not be resistant to antibiotics. Bacteria according to the present invention may also be transformed with DNA encoding an antigenic protein. Such transformed bacteria may be used to formulate a vaccine, in order to stimulate an immune response to the antigenic protein in a patient. The present invention further provides a method for isolating gram-positive bacteria resistant to FUdR.

Abstract: The DegP (HtrA) protease is a multifunctional protein essential for the removal of misfolded and aggregated proteins in the periplasm. The present invention provides an assay for inhibitors of DegP activity, comprising mixing a suspected inhibitor of DegP activity with DegP and a suitable substrate (preferably a native substrate of DegP such as PapA) and detecting changes in DegP activity. DegP has been shown to be essential for virulence in several Gram negative pathogens. Only three natural targets for DegP have been described: colicin A lysis protein (Cal), pilin subunits (K88, K99, Pap) and recently HMW1 and HMW2 from Hemophilus influenzae. In vitro, DegP has shown weak protease activity on casein and several other non-native substrates. The present inventors have identified the major pilin subunit of the Pap pilus, PapA, as a native DegP substrate and demonstrated binding and proteolysis of this substrate in vitro.