Cellular Protrusions Engage Viral Infection Enhancing EF-C Peptide Nanofibrils

Abstract

Self-assembling peptide nanofibrils (PNF) have gained increasing attention as versatile molecules in material science and biomedicine. One important application of PNF is to enhance retroviral gene transfer, a technology that has been central to the development of gene therapy. The best-investigated and commercially available PNF is derived from a 12-mer peptide termed EF-C. The mechanism of transduction enhancement depends on the polycationic surface of EF-C PNF, which binds to the negatively charged membranes of viruses and cells thereby overcoming electrostatic repulsion and increasing virion attachment and fusion. Assuming an even distribution of charges at the surfaces of virions and cells would result in an evenly distributed interaction of the virions with the cell surface. However, we here report that PNF do not randomly bind at the cell surface but are actively engaged by cellular protrusions. Chemical suppression of protrusion formation in cell lines and primary CD4+ T cells greatly reduced fibril binding and hence virion binding. Thus, the mechanism of PNF-mediated viral transduction enhancement involves active engagement of virus-loaded fibrils by cellular protrusions.

Supramolecular Peptide Nanofibrils with Optimized Sequences and Molecular Structures for Efficient Retroviral Transduction

“…[ 18 ] EF‐C PNFs efficiently concentrate virus stock solutions and increase cell attachment as well as retroviral gene transfer into hematopoietic stem cells and T cells by different types of vectors in vitro and ex vivo, which holds various opportunities for gene therapy approaches, in particular chimeric antigen receptor T cell (CAR‐T) immunotherapy. [ 18,34–36 ] Compared to other PNFs and known transduction enhancers, EF‐C reveals one of the highest enhancing effects on retroviral gene transfer and has been commercialized under the brand name Protransduzin. [ 34 ]…”

Optimized peptide nanofibrils as efficient transduction enhancers for in vitro and ex vivo gene transfer

“…We previously identified the 12-mer peptide EF-C that selfassembles into peptide nanofibrils (PNFs) and efficiently enhances g-retroviral gene transfer in various in vitro settings (25). The application of EF-C for CAR-T cell generation is however limited due to its time-dependent chemical instability and the formation of large aggregates under cellular conditions (32). Additionally, its sequence is derived from HIV-1 glycoprotein gp120 (25), which may potentially induce immunogenicity.…”

“…This makes it a more cost-effective and user-friendly alternative. However, the chemical instability of Protransduzin, caused by the cyclization of its N-terminal glutamine to pyroglutamate, presents a challenge, which leads to significant aggregate formation in cell culture (32).…”