The invention provides compositions, kits and methods utilizing polypeptides having a viral alpha-helix heptad repeat domain in a stabilized α-helical structure (herein also referred to as SAH). The compositions are useful for treating and/or preventing viral infections. The invention is based, at least in part, on the result provided herein demonstrating that viral hydrocarbon stapled alpha helical peptides display excellent proteolytic, acid, and thermal stability, restore the native alpha-helical structure of the peptide, are highly effective in interfering with the viral fusogenic process, and possess superior pharmacokinetic properties compared to the corresponding unmodified peptides.