Disclosed are polypeptides which include an amino acid sequence corresponding to CCXXXCKEGXXC (SEQ ID NO:1). Also disclosed are methods for inhibiting the activity of a flavivirus or other virus by contacting the virus with a miniprotein ligand under conditions effective for the miniprotein ligand to bind to the virus. Methods for detecting a flavivirus or other virus in a sample by contacting the sample with a miniprotein ligand and determining whether the miniprotein ligand is bound to a flavivirus or other virus as also disclosed, as are methods of assessing a compound's usefulness in inhibiting the activity of a flavivirus or other virus.