We further analyzed the lymphocyte composition of the spleen on day 6 after WNV infection (Fig 7) . Gross pathologic analysis revealed that WNV infection of IPS-1 2/2 mice results in massive splenomegaly whereas infection of wild type mice induces only a slight increase in spleen size (Fig 7A) . Cell analysis revealed increased numbers of total lymphocytes in the spleens of infected IPS-1 2/2 mice as compared to wild type mice (Fig 7B) .