This invention relates to bispecific fusion proteins effective in viral neutralization. More specifically, such proteins have two different binding domains, an inducing-binding domain and an induced-binding domain, functionally linked by a peptide linker. Such proteins, nucleic acid molecules encoding them, and their production and use in preventing or treating viral infections are provided. One prototypical bispecific fusion protein is sCD4-SCFv(17b), in which a soluble CD4 fragment (containing domains D1 and D2) is fused to a single chain Fv portion of antibody 17b via a linker.
