Disclosed herein is a method of treating influenza A virus (IAV) infection by a fusion protein. According to some embodiments of the present disclosure, the fusion protein comprises a HBD peptide and a IgG1 Fc region. According to other embodiments of the present disclosure, the fusion protein comprises a DcR3 protein and a IgG1 Fc region. The present fusion protein is found to possess inhibitory effects on IAV-induced secretion of the inflammatory cytokine, and IAV-induced infiltration of inflammatory cell into the lung tissue. Accordingly, the fusion protein is useful for developing a medicament for the treatment or prophylaxis of IAV infection and/or ameliorating pulmonary injury caused by excessive inflammation associated with IAV infection in a subject.
