Importance of the Number and Position of Tryptophan-Aspartate Repeats in Designing Peptide-Based Membrane Fusion Inhibitors.

Enveloped viruses utilize membrane fusion to enter the host cell and cause viral diseases. Most conventional inhibitors are target-specific and ineffective against broad-spectrum viral infections. Therefore, the current scenario demands developing inhibitors to attenuate the membrane properties instead of targeting the viral proteins. In the present work, we have designed a new WD-containing peptide (dmTG-23) by introducing a WD repeat at the center of the peptide sequence using mTG-23 peptide as a template and a 14-amino acid peptide with seven WD repeats (WD-14), and tested their efficacies against the polyethylene glycol (PEG)-induced fusion assay. Our findings show that both dmTG-23 and WD-14 prevent PEG-induced fusion of small unilamellar vesicles (SUVs) with varying cholesterol concentrations, with a higher effect for dmTG-23. Moreover, we have compared our results with our previous observations on TG-23 and mTG-23 to evaluate the importance of the number and position of WD repeats in the peptide sequence to impart the highest inhibitory activity. Our results demonstrate that three WD repeat-containing dmTG-23 shows the highest efficacy against the PEG-induced fusion of SUVs by enhancing the membrane order at the acyl chain region. This result is significantly important in designing peptide-based broad-spectrum fusion inhibitors.