RNAseq Reveals the Contribution of Interferon Stimulated Genes to the Increased Host Defense and Decreased PPR Viral Replication in Cattle

Peste des petits ruminants virus (PPRV) is known to replicate in a wide variety of ruminants causing very species-specific clinical symptoms. Small ruminants (goats and sheep) are susceptible to disease while domesticated cattle and buffalo are dead-end hosts and do not display clinical symptoms. Understanding the host factors that influence differential pathogenesis and disease susceptibility could help the development of better diagnostics and control measures. To study this, we generated transcriptome data from goat and cattle peripheral blood mononuclear cells (PBMC) experimentally infected with PPRV in-vitro. After identifying differentially expressed genes, we further analyzed these immune related pathway genes using the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) and selected candidate genes were validated using in-vitro experiments. Upon PPRV infection, we identified 12 and 22 immune related genes that were differentially expressed in goat and cattle respectively. In both species, this included the interferon stimulated genes (ISGs) IFI44, IFI6, IFIT1, IFIT2, IFIT3, ISG15, Mx1, Mx2, OAS1X, RSAD2, IRF7, DDX58 and DHX58 that were transcribed significantly higher in cattle. PPRV replication in goat PBMCs significantly increased the expression of phosphodiesterase 12 (PDE12), a 2′,5′-oligoadenylate degrading enzyme that contributes to the reduced modulation of interferon-regulated gene targets. Finally, a model is proposed for the differential susceptibility between large and small ruminants based on the expression levels of type-I interferons, ISGs and effector molecules.