The present disclosure relates to polypeptides that specifically bind to Dengue virus non¬structural protein 1, including antibodies and fragments thereof. The antibody or antigen-binding fragment thereof may specifically bind Dengue virus (DENV) serotype 4 and include: a heavy chain variable region that comprises at least one CDR amino acid sequence selected from the group consisting of: SGYNWH, YIH YS GGTN YNPS LKS, RTGTVPFAY, SYVMH, YLNPYNDDTKYNEKFKG, and GPPYALDY. The present disclosure further relates to methods of producing the polypeptides of the present disclosure, methods of diagnosing DENV, and methods of treating a DENV infection.