Leila Sharifi, Jahanbakhsh Ghasemi, Leo Santisi, Shivangi Naik, Willow DiLuzio, Arani Chanda, Bodhisattwa Chaudhuri
These findings provide mechanistic insight into the stabilizing effect of P188 on AAV via concentration-dependent surface coverage and steric hindrance that minimize capsid-capsid interactions associated with aggregation. The reported concentrations are nominal finite-box values defined by discrete P188 molecule counts and represent comparative simulation conditions rather than experimentally derived formulation thresholds. These findings provide a molecular basis for understanding P188-mediated AAV stabilization and for guiding formulation optimization.
PURPOSE: Aggregation of adeno-associated virus (AAV) during manufacturing and storage remains a challenge in gene therapy formulation. This study evaluates how varying Poloxamer188 (P188) concentrations affect the structural stability and aggregation behavior of two full AAV8 capsids.
METHODS: Coarse-grained molecular dynamics simulations of AAV8 capsids with P188 were performed for 4000 ns at 300 K. Center-of-mass (COM) separation, residue-level contacts, surface coverage, van der Waals interactions, radius of gyration (Rg), relative shape anisotropy (k2), and simulation snapshots were analyzed.
RESULTS: Persistent capsid association was not observed in systems containing 10 or 24 P188 molecules (0.15% and 0.35% w/v), whereas systems containing 2 or 5 P188 molecules (0.03% and 0.07% w/v) showed delayed association relative to the surfactant-free system. Capsid surface coverage increased with P188 loading. Polyethylene oxide (EO) segments associated with the capsid surface early and persistently, followed by gradual polypropylene oxide (PO) engagement, indicating a preferential/sequential interaction mechanism. Higher P188 loadings showed negligible van der Waals attraction, consistent with steric shielding. Chain-resolved Rg and k2 profiles indicated initial conformational rearrangement followed by stabilization of distinct surface-associated P188 conformations, with varying spatial extension and shape anisotropy.
CONCLUSIONS: These findings provide mechanistic insight into the stabilizing effect of P188 on AAV via concentration-dependent surface coverage and steric hindrance that minimize capsid-capsid interactions associated with aggregation. The reported concentrations are nominal finite-box values defined by discrete P188 molecule counts and represent comparative simulation conditions rather than experimentally derived formulation thresholds. These findings provide a molecular basis for understanding P188-mediated AAV stabilization and for guiding formulation optimization.