Proteins on the surface of bacterial, cellular or viral membranes play a fundamental role in a number of biological functions: adhesion, cell communication and identification, nutrient transport, adaptation to the environment, etc.
Targeting and modifying these surface proteins will make it possible to impart new properties to viral vectors used in gene therapy, or stem and immune cells used in regenerative and anticancer cell therapy. Indeed, these modifications may allow the natural tropism of these entities to be directed to target organs for the delivery of a gene of interest, chemical probes, or cytotoxic molecules. This prospect justifies significant efforts aimed at developing efficient and reliable methods for molecular transplantation onto the surface of viruses, bacteria or living cells.
Currently, the preferred method remains the expression of the sugar, which represents a “chemical tag” accessible to chemical reactions. However, it requires culturing bacteria/cells for several hours/days in the presence of modified sugars, the rate of incorporation of these sugars varies among cell lines and is not applicable to viruses. Therefore, it is critical to develop alternative methods to avoid this bioincorporation step.
Scientists from the fields of chemistry and interdisciplinarity, synthesis, analysis, modeling (CNRS/Nantes University), translational research in gene therapy (INSERM, Nantes University) and Department of Biological Sciences and Biotechnology (CNRS/Nantes University) succeeded in functionalizing the surface of viral vectors, bacteria and cells using electrochemistry*. Tested on recombinant adeno-associated viruses (rAAV2) used in gene therapy, their synthesis method can be accomplished in minutes to produce functionalized viral vectors that retain both their structural integrity and their infectious properties. In case of bacterial strainscoli (Gram-) and Staphylococcus epidermidis (Gram+), as well as using several lines of eukaryotic cells, scientists obtained labeled bacteria and cells that did not affect their viability and retained the ability to divide.
This easy-to-implement method, published in the journal Nat. General.should allow optimization of the design of viral, bacterial and cellular therapeutic vectors.
Electrochemical Click (eY-Click) method for labeling viral, bacterial and cellular surfaces. a) Labeling can be carried out in one step (eY-Click) on surface protein phenols or in two steps (eY-Click + azide-alkyne cyclization). b) Viruses, bacteria and cells are modified on the surface. Fluorescence microscopy image. Two-step labeling of S. epidermidis after 15 min of eY-Click with an NML-N3 anchor followed by azide-alkyne cyclization with functionalized rhodamine. c) The functionalized NML anchor is activated directly in an aqueous solution of virus, bacteria or cells after immersing a three-electrode system and applying a potential difference. © Sebastien Gouin