The major alterations found during disease development were: 1) Lethality preceded by development of hemoconcentration, thrombocytopenia, elevated transaminase levels associated with important liver injury, marked body weight loss and reduction in systolic blood pressure; 2) Increased levels of cytokines, including IFN-γ, IL-6, TNF-α, Il-12/23p40 and IL-18; 3) Increased viral load in spleen, liver and blood, virus NS1 antigen serum levels and NS3-staining in hepatocytes of infected mice. The gene discussed is IL18; the disease is Thrombocytopenia.