Proteins on the surface of bacterial, cellular or viral membranes play a fundamental role in a number of biological functions: adhesion, cellular communication and identification, transport of nutrients, adaptation to the environment, etc.
Acting on these surface proteins and modifying them would make it possible to give new properties to viral vectors used in gene therapy or to stem and immune cells used in regenerative and cancer cell therapies. In fact, these modifications could make it possible to direct the natural tropism of these entities to the target organs to deliver a gene of interest, chemical probes or cytotoxic molecules. This perspective justifies the significant efforts to develop efficient and reliable methods for molecular transplantation on the surface of viruses, bacteria or living cells.
Currently, the method of choice remains the expression of a sugar that presents a “chemical tag” amenable to click chemistry reactions. However, it requires cultivating the bacteria/cells for several hours/days in the presence of the modified sugar; the incorporation rate of these sugars varies depending on the cell line and is not applicable to viruses. It is therefore urgent to develop alternative methods to avoid this bioincorporation step.
Scientists from the laboratories of Chemistry and Interdisciplinarity, Synthesis, Analysis, Modeling (CNRS/University of Nantes), Translational Research in Gene Therapy (INSERM, University of Nantes) and Biological Sciences and Biotechnologies (CNRS/University of Nantes) have succeeded in functionalizing through electrochemistry * the surface of viral vectors, bacteria and cells. Tested on recombinant adeno-associated viruses (rAAV2) used in gene therapy, their synthesis method can be performed in minutes to produce functionalized viral vectors that retain both their structural integrity and infectious properties. In the bacterial strains Escherichia coli (Gram-) and Staphylococcus epidermidis (Gram+), as well as in several eukaryotic cell lines, scientists have obtained labeled bacteria and cells that do not affect their viability and retain their ability to divide.
This easy-to-implement method, published in the journal Nat. Commun. is intended to make it possible to optimize the design of viral, bacterial and cellular therapeutic vectors.
Dike Click electrochemical method (eY-Click) for labeling viral, bacterial and cellular surfaces. a) Labeling can be done in one step (eY-Click) on the phenols of surface proteins or in two steps (eY-Click + azide-alkyne cyclization). b) Viruses, bacteria and cells are changed on the surface. Fluorescence microscopic image. Two-step labeling of S. epidermidis after 15 minutes of eY-Click with an NML-N3 anchor and subsequent azide-alkyne cyclization with a functionalized rhodamine. c) The functionalized NML anchor is activated directly in the aqueous solution of viruses, bacteria or cells after immersing a system of three electrodes and applying a potential difference. © Sebastien Gouin