Key symptoms developing in MCMV-infected BALB/c mice were previously described [13] and include severe weight loss, fever on day 2 post infection, hypothermia on day 5 post infection, pancytopenia, hemophagocytosis in different organs and in peripheral blood, hyperferritinemia, elevated plasma levels of soluble CD25 (sCD25), a decreased percentage of natural killer (NK) cells in different organs and in peripheral blood, increased plasma levels of liver enzymes (alanine transaminase, ALT), and enlarged lymph nodes. The gene discussed is GPT; the disease is isolated hyperferritinemia.