Sequence and expression analysis of deer mouse interferon-γ, interleukin-10, tumor necrosis factor, and lymphotoxin-α

Deer mice (Peromyscus maniculatus) are the principal host species of Sin Nombre (SN) virus, the primary etiologic agent of hantavirus cardiopulmonary syndrome in North America. The disease is a cytokine-mediated immunopathology characterized by pulmonary mononuclear infiltrates without discernible viral pathology. Infected deer mice remain life-long carriers and virus is found in many organs, including the lungs, but without pathology. It is unclear how deer mice respond to SN virus because no tools exist to examine the immune response in infected animals. As an initial step in examining host responses to SN virus, we have cloned partial cDNAs of deer mouse interferon-γ (IFN-γ), interleukin-10 (IL-10), tumor necrosis factor (TNF) and lymphotoxin-α (LTα). IL-10, TNF and LTα sequences are highly conserved compared to orthologs of other mammalian species, while IFN-γ is substantially less conserved. Phylogenetic analyses indicate that the amino acid sequences of IFN-γ and TNF may be useful in resolving relationships at the subfamily level within the rodent family Muridae. While all four sets of analyses were able to reconstruct clade Rodentia, they were not able to resolve the relationships among the mammalian orders represented in this study. Reverse transcriptase polymerase chain reaction (RT-PCR) analysis of concanavalin A-stimulated splenocytes determined that maximal IFN-γ and TNF expression occurred rapidly while IL-10 and LTα expression was maximal at 24 h.