| Summary: | Previously, we showed that bacterial lipopolysaccharide (LPS) converts mouse PrP<sup>C</sup> protein to a beta-rich isoform (moPrP<sup>res</sup>) resistant to proteinase K. In this study, we aimed to test if the LPS-converted PrP<sup>res</sup> is infectious and alters the expression of genes related to prion pathology in brains of terminally sick mice. Ninety female FVB/N mice at 5 weeks of age were randomly assigned to 6 groups treated subcutaneously (sc) for 6 weeks either with: (1) Saline (CTR); (2) LPS from <i>Escherichia coli</i> 0111:B4 (LPS), (3) one-time sc administration of de novo generated mouse recombinant prion protein (moPrP; 29-232) rich in beta-sheet by incubation with LPS (moPrP<sup>res</sup>), (4) LPS plus one-time sc injection of moPrP<sup>res</sup>, (5) one-time sc injection of brain homogenate from Rocky Mountain Lab (RLM) scrapie strain, and (6) LPS plus one-time sc injection of RML. Results showed that all treatments altered the expression of various genes related to prion disease and neuroinflammation starting at 11 weeks post-infection and more profoundly at the terminal stage. In conclusion, sc administration of de novo generated moPrPres, LPS, and a combination of moPrP<sup>res</sup> with LPS were able to alter the expression of multiple genes typical of prion pathology and inflammation.
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