A method for reducing mortality resulting from viral infection, reducing viral load resulting from viral infection, or increasing immunity to viral infection in a subject is described. The method comprises administering a hybrid protein comprises a first domain comprising a sequence encoding a surface protein of an enveloped RNA virus and a second domain comprising a sequence encoding an ectodomain of a type 2 transmembrane domain protein, wherein the second domain is located at the C-terminal of the first domain. The hybrid protein or an mRNA encoding such protein can be used as a vaccine against the infection of the enveloped RNA virus.