NS = Not significant. C. Oral inoculations of Balb/c mice with EGD-e::pIMC3kan #see more randurls[1|1|,|CHEM1|]# and EGD-e InlA m * ::pIMCery mixed

at a 1:1 ratio in a total inoculum of 1 × 1010 cfu/200 μl containing 100 mg of CaCO3. *** = p < 0.005. D. Competitive index virulence in a Balb/c oral infection model with EGD-e InlA m * ::pIMC3ery competed against EGD-e::pIMC3kan, EGD-e A::pIMC3kan (InlA-N259Y), EGD-e B::pIMC3kan (InlA-Q190L), EGD-e C::pIMC3kan (InlA-T164A/K301I/G303E) or EGD-e D::pIMC3kan (InlA-S173I/L185F/L188I) as described in C. The invasion levels were significantly (p < 0.005) different than EGD-e InlA m * for all competed strains. Figure 8 Bioluminescent imaging (BLI) of Balb/c mice orally infected with either EGD-e or EGD-e InlA m* (tagged with pIMK2 lux ). A. Balb/c mice (five per group) were gavaged with a total of 5 × 109 cfu and the progression of infection in each mouse (labelled 1 thru 5) followed on day one, two and three by BLI. Pseudocolor overlay represents the light emission profile from the infected mice with the scale bar on the right hand side. On day three mice were euthanized selleck chemical and livers examined ex vivo by BLI. B. Total bacterial loads from livers and spleens were numbered. The cross line denotes the mean organ cfu recovery for the five mice.

Statistical analysis was conducted using a student t test with the p-value shown on the graph. Discussion It is now well established that the murine model of listeriosis is limited by a poor interaction between the bacterial invasion protein InlA and its host ligand mCDH1. This is in direct contrast, to the efficient interaction between InlA and hCDH1. The discrepancy is due to a glutamate at residue 16 in mouse (and rat) E-cadherin rendering these host species relatively resistant to infection by the oral route and limiting their use

as laboratory models for certain L. monocytogenes-mediated disease processes [11]. Recent studies have developed an engineered mouse strain expressing ‘humanized’ E-cadherin for studies of oral and fetoplacental listeriosis [14]. An alternative approach has utilized structure-based ifenprodil engineering to ‘murinize’ the bacterial InlA protein in order to increase affinity for murine E-cadherin [17]. This approach has provided key insights into the interaction between InlA and CDH1. While murinization was highly successful, we reasoned that additional points of contact may also improve the interaction with mCDH1. We therefore developed a system to select random mutations in InlA that enhance invasion of murine cells in order to identify novel amino acid interactions and to determine if ‘murinization’ of the strain can be improved. L. lactis was used as a surrogate host for this process in order to prevent generation of Listeria mutants with increased affinity for human cells.