Sin Nombre virus pathogenesis in Peromyscus maniculatus

Sin Nombre virus (SNV), a member of the Hantavirus genus, causes acute vira l pneumonia in humans and is thought to persistently infect mice. The deer mouse, Peromyscus maniculatus, has been identified as the primary reservoir host for SNV, To understand SNV infection of P. maniculatus, we examined w ild deer mice for localization of viral antigens and nucleic acid. Morpholo gic examination consistently revealed septal edema within lung tissue and m ononuclear cell infiltrates in portal areas of the liver. Immunohistochemic al analysis of SNV-infected deer mice identified viral antigens within lung , liver, kidney, and spleen. The lungs consistently presented with the high est levels of viral antigen by immunohistochemistry and with the highest le vels of nucleic acid by reverse transcriptase (RT) PCR. The mononuclear cel l infiltrates surrounding liver portal triads were positive for SNV antigen s in addition to resident macrophages in liver sinuses. Spleen tissue conta ined antigens in both the red pulp and the periartereolar region of the whi te pulp. The kidney presented with no gross pathology, although antigens co uld be localized to glomeruli. Virus antigen levels within the kidney were highest in deer mice that did not have antibodies to SNV but contained vira l nucleic acid detectable by RT PCR. Since transmission is thought to occur via urine, our results suggest that virus transmission may be highest in t he early stages of infection. In addition, these results indicate that SNV does cause some pathology within its reservoir host.