Peptide inhibition of human cytomegalovirus infection

Melnik, Lilia I; Garry, Robert F; Morris, Cindy A

Previous studies have suggested that synthetic peptides corresponding to or overlapping with sequences in viral fusion proteins that have positive WWIHS scores can sometimes serve as viral entry inhibitors [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] [49] [50] . For example, Enfurvitide (Fuzeon) is a 36-amino acid peptide that overlaps with a WWIHS score-positive sequence in the transmembrane protein (TM) of HIV-1, and prevents viral fusion and entry of the virus. To identify regions of HCMV gB that have a high propensity to interact with the lipid bilayer of cell membranes and which potentially may serve as HCMV entry inhibitors, we employed Membrane Protein eXplorer version 3.0 (http://blanco.biomol.uci.edu/mpex), a computer program based on the WWIHS. Nine sequences with significant positive WWIHS scores were identified ( Figure 2 ). As expected, several of these WWIHS sequences corresponded to the predicted fusion domain of HCMV gB, including the predicted fusion loops. One of the WWIHS score-positive sequences spanned amino acids 146 to 200 (peptide 146-200) that had a ΔG score of 4.33 kcal/mol. This sequence was split into two smaller peptides: 146-173 and 174-200. A second large Figure 1 Wimley-White interfacial hydrophobicity scale score-positive sequences in class II and III viral fusion proteins. Sequences of a representative class II viral fusion protein (Dengue virus E) and of class III viral fusion proteins with high potential to interface with lipid membranes (red) were identified using Membrane Protein Explorer software (MpeX version 3.0). As discussed in the text, a class III domain nomenclature is used here that can apply to both class II and III viral fusions proteins. The alternative domain number schemes used by Roche et al. and Heldwein et al. are noted in parentheses. The Dengue virus (DENV E) stem domain sequence that was not included in the protein used to determine the crystal structure has been added. The DENV stem has a positive WWIHS scale score, and corresponds to a previously determined inhibitor of DENV and West Nile virus [35] . segment within the fusion domain of HCMB gB had a ΔG score of 3.39, and was split, consequently, into smaller peptides: 233-263 and 264-291. An additional peptide, 297-315 corresponding to another fusion domain sequence, was also synthesized, along with an additional 4 peptides corresponding to other WWIHS-positive domains of HCMV gB. To prevent dimer formation, cysteines were replaced with alanines.