IPS-1 2/2 (C57BL/66129Sv/Ev) and their wild type littermate control mice have been published [38, 61] and were obtained as a generous gift from Dr. S. Akira (Osaka University, Osaka, Japan). Mice were genotyped and bred under pathogen-free conditions in the animal facility at the University of Washington. Experiments were performed with approval from the University of Washington Institutional Animal Care and Use Committee. The methods for mice use and care were performed in accordance with the University of Washington Institutional Animal Care and Use Committee guidelines. Age-matched six to twelve week old mice were inoculated subcutaneously (s.c.) in the left rear footpad with 100 PFU of WN-TX in a 10 ml inoculum diluted in Hanks balanced salt solution (HBSS) supplemented with 1% heatinactivated FBS. Mice were monitored daily for morbidity and mortality.