Abstract: Described herein are peptides, compositions, and method of treating measles or HIV infection with antiviral peptide conjugates comprising a fusion inhibitory peptide (FIP) conjugated to a C-terminal heptad repeat (HRC) peptide. Also described herein are soluble stabilized measles F proteins, compositions, and method of preventing measles infection with the stabilized F protein, which can be administered alone, or in combination with the antiviral peptide conjugates described herein.