Abstract: The present invention provides compositions of protein mimetics and methods of using same against HIV-1, SARS-coV and the like. In one aspect, the present invention relates to a protein mimetic for preventing HIV-1 entry to host cells of a living subject through membrane fusion, wherein HIV-1 contains at least one envelope glycoprotein gp41 that has a plurality of peptides in a pre-hairpin state. In one embodiment, the protein mimetic comprises at least two monomeric peptide strands and an interstrand linker coupling the monomeric peptide strands. The coupled monomeric peptide strands prevent the plurality of trimeric gp41 in a pre-hairpin state from transiting to a six-helix hairpin bundle, thereby inhibiting HIV-1 entry to the host cells through membrane fusion.