This C34 peptide, also known as HR2, belongs to the helical region of gp41 of HIV, C-terminal heptad repeat 2 (HR2) defined as C helix or C peptide. It is known that HIV-1 enters cells by membrane fusion, C34 gp41 peptide act as an inhibitors against HIV, respiratory syncytial virus (RSV), human parainfluenza virus (HPV) and also exhibit antifusogenic properties.