Charged Polymers Modulate Retrovirus Transduction via Membrane Charge Neutralization and Virus Aggregation

Abstract

The specific mechanisms of charged polymer modulation of retrovirus transduction were analyzed by characterizing their effects on virus transport and adsorption. From a standard colloidal perspective two mechanisms, charge shielding and virus aggregation, can potentially account for the experimentally observed changes in adsorption behavior and biophysical parameters due to charged polymers. Experimental testing revealed that both mechanisms could be at work depending on the characteristics of the cationic polymer. All cationic polymers enhanced adsorption and transduction via charge shielding; however, only polymers greater than 15 kDa in size were capable of enhancing these processes via the virus aggregation mechanism, explaining the higher efficiency enhancement of the high molecular weight molecules. The role of anionic polymers was also characterized and they were found to inhibit transduction via sequestration of cationic polymers, thereby preventing charge shielding and virus aggregation. Taken together, these findings suggest the basis for a revised physical model of virus transport that incorporates electrostatic interactions through both virus-cell repulsive and attractive interactions, as well as the aggregation state of the virus.

Engineering graded tissue interfaces

“…As a first step toward creating a heterogeneous interface, we explored the feasibility of genetically modifying fibroblasts in situ within tissue constructs using biomaterial-mediated retroviral gene transfer. Runx2 retrovirus was immobilized onto collagen scaffolds by exploiting the ability of cationic polymers, in this case poly(L-lysine) (PLL), to charge neutralize and aggregate viral particles (21,22). Collagen scaffolds were uniformly coated with 0.01% PLL and incubated in retroviral supernatant for 4-5 h before seeding with primary dermal fibroblasts.…”

Molecular Determinants of Vectofusin-1 and Its Derivatives for the Enhancement of Lentivirally Mediated Gene Transfer into Hematopoietic Stem/Progenitor Cells

“…fibronectin fragments (19 -21), protamine sulfate (22), prostatic acid phosphatase fragments (23), or HIV-1 gp41-and gp120-derived peptides (24,25)). These mostly cationic additives have the capacity to neutralize membrane charges and promote viral adhesion, viral fusion (2), virus aggregation (26), and/or virus pulldown through the formation of nanofibrillar structures (27). For clinical applications, transduction protocols usually include the human fibronectin fragment CH-296 (also called Retronectin).…”

Poly-l-lysines and poly-l-arginines induce leakage of negatively charged phospholipid vesicles and translocate through the lipid bilayer upon electrostatic binding to the membrane

“…PLL, PLA [18] and their shorter homologues oligo-arginine [14] and oligo-lysine assist this process according to their abilities of charge shielding and aggregation when binding to negatively charged membranes and/or drug molecules [19]. This effect plays a role in the cellular uptake of viruses [11,12] and oligonucleotides [6].…”