C5AR1 and infection: In a mouse model of middle east respiratory syndrome coronavirus (MERS-CοV) infection, complement overactivation and excessive cytokine production was reported with elevated levels of C5a in lung and serum samples, while inhibition of C5aR was shown to reduce viral replication and alveolar damage possibly by decreasing alveolar macrophage infiltration and interferon (IFN)-γ receptor expression [80].