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Coxsackievirus type B3 (CVB3) is a cardiotropic enterovirus. Infection causes cardiomyocyte necrosis and myocardial inflammation. The damaged tissue that results is replaced with fibrotic or calcified tissue, which can lead to permanently altered cardiac function. The extent of pathogenesis among individuals exposed to CVB3 is dictated by a combination of host genetics, viral virulence, and the environment. Here, we aimed to identify genes that modulate cardiopathology following CVB3 infection. 129S1 mice infected with CVB3 developed increased cardiac pathology compared to 129X1 substrain mice despite no difference in viral burden. Linkage analysis identified a major locus on chromosome 7 (LOD: 8.307, P

Salmonella, a ubiquitous Gram-negative intracellular bacterium, is a food borne pathogen that infects a broad range of hosts. Infection with Salmonella Typhimurium in mice is a broadly recognized experimental model resembling typhoid fever in humans. Using a N-ethyl-N-nitrosurea (ENU) mutagenesis recessive screen, we report the identification of Ity16 (Immunity to Typhimurium locus 16), a locus responsible for increased susceptibility to infection. The position of Ity16 was refined on chromosome 8 and a nonsense mutation was identified in the ankyrin 1 (Ank1) gene. ANK1 plays an important role in the formation and stabilization of the red cell cytoskeleton. The Ank1(Ity16/Ity16) mutation causes severe hemolytic anemia in uninfected mice resulting in splenomegaly, hyperbilirubinemia, jaundice, extramedullary erythropoiesis and iron overload in liver and kidneys. Ank1(Ity16/Ity16) mutant mice demonstrated low levels of hepcidin (Hamp) expression and significant increases in the expression of the growth differentiation factor 15 (Gdf15), erythropoietin (Epo) and heme oxygenase 1 (Hmox1) exacerbating extramedullary erythropoiesis, tissue iron deposition and splenomegaly. As the infection progresses in Ank1(Ity16/Ity16), the anemia worsens and bacterial load were high in liver and kidneys compared to wild type mice. Heterozygous Ank1(+/Ity16) mice were also more susceptible to Salmonella infection although to a lesser extent than Ank1(Ity16/Ity16) and they did not inherently present anemia and splenomegaly. During infection, iron accumulated in the kidneys of Ank1(+/Ity16) mice where bacterial loads were high compared to littermate controls. The critical role of HAMP in the host response to Salmonella infection was validated by showing increased susceptibility to infection in Hamp-deficient mice and significant survival benefits in Ank1(+/Ity16) heterozygous mice treated with HAMP peptide. This study illustrates that the regulation of Hamp and iron balance are crucial in the host response to Salmonella infection in Ank1 mutants.

Cerebral malaria (CM) is a lethal neurological complication of malaria. We implemented a genome-wide screen in mutagenized mice to identify host proteins involved in CM pathogenesis and whose inhibition may be of therapeutic value. One pedigree (P48) segregated a resistance trait whose CM-protective effect was fully penetrant, mapped to chromosome 8, and identified by genome sequencing as homozygosity for a mis-sense mutation (W81R) in the FERM domain of Janus-associated kinase 3 (Jak3). The causative effect of Jak3(W81R) was verified by complementation testing in Jak3(W81R/-) double heterozygotes that were fully protected against CM. Jak3(W81R) homozygotes showed defects in thymic development with depletion of CD8(+) T cell, B cell, and NK cell compartments, and defective T cell-dependent production of IFN-γ. Adoptive transfer of normal splenocytes abrogates CM resistance in Jak3(W81R) homozygotes, an effect attributed to the CD8(+) T cells. Jak3(W81R) behaves as a dominant negative variant, with significant CM resistance of Jak3(W81R/+) heterozygotes, compared to CM-susceptible Jak3(+/+) and Jak3(+/-) controls. CM resistance in Jak3(W81R/+) heterozygotes occurs in presence of normal T, B and NK cell numbers. These findings highlight the pathological role of CD8(+) T cells and Jak3-dependent IFN-γ-mediated Th1 responses in CM pathogenesis.