Structure–Stability–Function Mechanistic Links in the Anti-Measles Virus Action of Tocopherol-Derivatized Peptide Nanoparticles

Abstract

Measles remains one of the leading causes of child mortality worldwide and is re-emerging in some countries due to poor vaccine coverage, concomitant with importation of measles virus (MV) from endemic areas. The lack of specific chemotherapy contributes to negative outcomes, especially in infants or immunodeficient individuals. Fusion inhibitor peptides derived from the MV Fusion protein C-terminal Heptad Repeat (HRC) targeting MV envelope fusion glycoproteins block infection at the stage of entry into host cells, thus preventing viral multiplication. To improve efficacy of such entry inhibitors, we have modified a HRC peptide inhibitor by introducing properties of self-assembly into nanoparticles (NP) and higher affinity for both viral and cell membranes. Modification of the peptide consisted of covalent grafting with tocopherol to increase amphipathicity and lipophilicity (HRC5). One additional peptide inhibitor consisting of a peptide dimer grafted to tocopherol was also used (HRC6). Spectroscopic, imaging, and simulation techniques were used to characterize the NP and explore the molecular basis for their antiviral efficacy. HRC5 forms micellar stable NP while HRC6 aggregates into amorphous, loose, unstable NP. Interpeptide cluster bridging governs NP assembly into dynamic metastable states. The results are consistent with the conclusion that the improved efficacy of HRC6 relative to HRC5 can be attributed to NP instability, which leads to more extensive partition to target membranes and binding to viral target proteins.

Intranasal fusion inhibitory lipopeptide prevents direct contact SARS-CoV-2 transmission in ferrets

“…We have previously demonstrated that lipid conjugation of HRC-derived inhibitory peptides markedly increases antiviral potency and in vivo half-life (13)(14)(15)(16), and used this strategy to create entry inhibitors for prophylaxis and/or treatment of human parainfluenza virus type 3, measles virus, and Nipah virus infection (14,15,(17)(18)(19)(20). Both dimerization and peptide integration into cell membranes proved key to ensure respiratory tract protection and prevent systemic lipopeptide dissemination (16,18).…”

Structural determinants conferring unusual long life in human serum to rattlesnake‐derived antimicrobial peptide Ctn[15‐34]

“…The hydrodynamic radius (R H ) of Ctn [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] particles was monitored over 12 hours at 500μM final concentration using a Malvern Zetasizer Nano ZS (Malvern, UK) in particle size analysis mode as previously described. 41 TABLE 1 Design rationale and synthesis data of Ctn [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] analogs in this study Note. Five-residue sequence blocks spanning the Lys-rich, helical-prone domain (red), or the hydrophobic domain (blue) were combined in different manners to give analogs 1 to 3.…”

Self-assembly Stability Compromises the Efficacy of Tryptophan-Containing Designed Anti-measles Virus Peptides

“…The atomistic structures were converted to the corresponding CG models using the martinize.py script [41], for subsequent simulation under the GROMACS 5.1 package [42]; (2) a 4-unit PEG linker, built from an existing CG model of PEG [43] was appended to the peptides. To simplify the CG modeling maleimide was not taken into account and was instead replaced by three PEG beads in the final models (for a total 7-unit PEG linker); (3) for the Chol-and Toc-conjugated peptides the previously described Chol [44] or Toc [45] models were appended to the linker segment. Parameters for linker connections followed those of the Cys sidechain particle that they replaced.For the aggregation simulations, boxes containing 8 peptide molecules and either 23075 Martini waters, 271 Na+ and 255 Cl-molecules for monomeric peptides, or 23051 Martini waters, 295 Na+ and 255 Cl-molecules for dimeric peptides, were used.…”

“…The molecular level effects of the Leu-to-Trp substitution in the self-assembly process remained unclear after the experiments above. We had previously shown that CG molecular dynamics can capture important features of inter-molecular association during the aggregation process of HRC5 and HRC6 peptides in a µs range timescale [45]. The same CG methodology was used to analyze the assembly of the HRC-L454W peptides.…”

“…Through contact counting analysis (Table 4), we quantified the aggregate bridge ratio (R A-A ). As described, this parameter corresponds to the simulation time involved in bridge interactions as a fraction of the total interaction time and has been shown to correlate with aggregation instability [45]. Here, it was employed to quantitatively characterize the HRC and HRC-L454W peptide aggregation processes and explain their differences.…”