Genetic mechanisms of Host-Salmonella interactions

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Overview : My research program is using Salmonella as model organism and forward genetics for studying the biology of intracellular infection and to elucidate the function of immune related genes. Forward genetics is an unbiased approach for providing important information on gene function essential to defined biological pathways. Once the host genes are identified in vivo, their molecular function is characterized using cell culture models. In the current program we are proposing to use mice of the collaborative cross (CC) as a new resource to study the interaction between the host and Salmonella. The CC is a large panel of inbred mouse strains derived from eight founder strains and interrogates multiple genes at the same time to reveal unsuspected gene functions and gene network relationships, making the CC an exceptional tool to model the complexity of host-Salmonella interaction.******Specific Objectives and Methodology : There are three specific objectives to the proposed research program : 1 Identification of novel mutations and pathways responsible for altered cellular response to Salmonella. This objective will be approached using Quantitative Trait Loci (QTL) mapping using bacterial load as phenotype. In parallel, we will perform expression QTL (eQTL) analysis in spleen to determine baseline phenotype in unchallenged CC mice to identify heritable genomic loci that contribute to the variation in immune function. 2 Cellular phenotyping of CC deviant strains will be achieved by determining the integrity, composition and activation status of immune cells present in different tissues using high throughput flow cytometry, evaluation of the integrity of TLR signalling in splenocytes and by using cell culture model of Salmonella infection. These experiments are important to better characterize at the cellular level the mechanisms involved in host Salmonella interaction in CC deviant strains and to relate the cellular phenotype to candidate genes in QTLs analysis. 3 Functional validation of candidate genes will be done using allelic complementation assays, siRNA technologies and/or cells derived from mice carrying a knock out allele at the candidate gene. ******Significance : This project will take advantage of cutting-edge genetic tools to explore new players of the complex host-Salmonella interaction. A major asset of this project is that the resources are both novel, ensuring the originality of the results that will be produced, and are readily available, which warranties the feasibility of the proposed work. The proposed program will advance our knowledge of the complex interaction of the host with Salmonella, and will lead to the identification of additional novel mechanisms most relevant to innate immunity. In long-term, this research program will provide detailed characterization of novel genes involved in immune cell function.