Buggy creek virus (Togaviridae: Alphavirus) upregulates expression of pattern recognition receptors and interferons in house sparrows (Passer domesticus)

Birds serve as reservoirs for at least 10 arthropod-borne viruses, yet specific immune responses of birds to arboviral infections are relatively unknown. Here, adult House Sparrows were inoculated with an arboviral alphavirus, Buggy Creek virus (BCRV), or saline, and euthanized between 1 and 3 days postinoculation. Virological dynamics and gene expression dynamics were investigated. Birds did not develop viremia postinoculation, but cytopathic virus was found in the skeletal muscle and spleen of birds 1 and 3 days postinoculation (DPI). Viral RNA was detected in the blood of BCRV-infected birds 1 and 2 DPI, in oral swabs 1-3 DPI, and in brain, heart, skeletal muscle, and spleen 1-3 DPI. Multiple genes were significantly upregulated following BCRV infection, including pattern recognition receptors (TLR7, TLR15, RIG-1), type I interferon (IFN-α), and type II interferon (IFN-γ). This is the first study to report avian immunological gene expression profiles following an arboviral infection.