This project has focused on characterizing the expression of the Type 1 interferon (IFN) by Lactobacillus and determining the consequences of administering control and transgenic Lactobacillus on dextran sodium sulfate induced gut inflammation. We successfully demonstrated that bacteria expressing the interferon but not the control bacteria, triggered rapid STAT1 phosphorylation and that this effect required contact between the bacteria and the macrophages. Furthermore, this effect was dependent on the interferon-beta receptor but did not require toll receptors 2 or 9. The expression of the interferon gene by the Lactobacillus also induced rapid STAT1 phosphorylation in primary murine dendritic cells as well as a mouse gut epithelial cell line. We also demonstrated direct secretion of IFN-beta by the transgenic bacteria. Current studies on the effects of the bacteria on DSS induced gut inflammation have yielded unexpected results. We have observed that administration of IFN-beta producing Lactobacillus actually worsens DSS induced colitis and our current data supports a model where the IFN-beta expression interferes with gut dendritic cell maturation, resulting in a more pro-inflammatory environment. As a second part of this project, we have developed a PCR assay for murine norovirus and have determined that norovirus can be detected in fecal pellets for at least 10-12 days following infection. We are now testing if administration of the Lactobacillus can alter the time course of infection. As a new part of this project, we have found that the Lactobacillus appear to secrete a chemotactic activity and we are in the process of purifying culture supernatant in an attempt to identify the active component.
