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Proceedings of the 31 st European Peptide SymposiumMichal Lebl, Morten Meldal, Knud J. Jensen, Thomas Hoeg-Jensen (Editors)European Peptide Society, 2010Improving Peptide Therapeutics for HIV andOther Viral DiseasesAntonello Pessi 1 , Matteo Porotto 2 , Christine Yokoyama 2 ,Laura M. Palermo 2 , Aparna Talekar 2 , Ilaria DeVito 2 , Barry Rockx 3 ,Heinz Feldmann 3 , Riccardo Cortese 4 , and Anne Moscona 21 PeptiPharma, 00040, Pomezia (RM), Italy; 2 Weill Medical College of Cornell University,NY, 10021, U.S.A.; 3 Laboratory of Virology, NIAID, NIH, Hamilton, MT, U.S.A.;4 CEINGE, Via Comunale Margherita 482, Naples, ItalyIntroductionFusion of enveloped viruses with the host cell is driven by specialized proteins. The“Class I” fusion proteins harbor two heptad-repeat (HR) regions, central to theconformational changes leading to fusion: HR1, adjacent to the fusion peptide, and HR2,immediately preceding the transmembrane domain [1]. Fusion is inhibited by HR2-derivedpeptides like, for HIV, C34 and T20: the latter is in clinical use with the name enfuvirtide.We have devised a general method to increase the potency of fusion inhibitors, by preconcentratingthe peptide in the membrane raft microdomains where viral fusion occurs.The method is based on the addition of a cholesterol group to the peptide (“cholesteroltagging”).We have previously described that for HIV, cholesterol-tagging of C34 led to adramatic increase in antiviral potency, yielding the most potent HIV fusion inhibitor knownto date [2]. We apply here cholesterol-tagging to another family of enveloped viruses, theparamixoviridae. In particular, we show that cholesterol tagging is highly effective forinhibition of the paramyxoviruses parainfluenza virus type 3 (HPIV3), a major cause oflower respiratory diseases in infants, and Nipah virus (NiV), an emerging zoonotic viruscausing lethal central nervous system diseases.Results and DiscussionIt is already known that peptides from the HR2 region of a number of paramyxoviruses caninhibit viral infectivity [3]. For the HR2 peptide derived from HPIV3, we have shown theability of inhibiting, in addition to the homologous HPIV3 virus, also NiV virus [4]. Whenwe applied cholesterol tagging to the HPIV3 HR2 peptide, we found considerably increasedFig. 1. Inhibiton of viral infection by cholesterol-tagged HPIV3 peptide. (Left) CV1 cellmonolayers were infected with wild-type HPIV3 at a multiplicity of infection (MOI) of6.7x10 -4 in the presence of increasing concentrations of cholesterol-tagged (filled circles)or untagged (empty circles) HPIV3 peptide. After 90 min cells were overlaid withmethylcellulose, and plaques were stained and counted after 18 h. (Right) 293T cellmonolayers were infected with NiV pseudotyped virus at an MOI of 0.25 in the presenceof increasing concentrations of tagged or untagged HPIV3 peptide. After 24 h, cells werecollected and fixed for FACS analysis. The sequence of the peptide isVALDPIDISIVLNKAKSDLEESKEWIRRSNQKLDSI, corresponding to residues 449-484of the fusogenic F protein, with the mutation Glu459→Val [4].298