Biology subjects

Davodeau, F.

Publications and source records attributed to Davodeau, F..

3 recordsLinked to original sources

bioRxiv2025

Optimized pipeline for generating highly potent neutralizing Affitins: application to SARS-CoV-2 spike protein

Viral infections represent a global health threat, causing three million deaths annually. Antiviral strategies primarily target viral genome replication or prevent virus entry into host cells. While most FDA-approved antiviral drugs are small chemical molecules, protein-based therapies like monoclonal antibodies (mAbs) offer advantages such as broad and high neutralizing activities, and ability to recruit immune responses to enhance viral clearance. Additionally, alternative protein scaffolds with favorable properties have been developed to substitute or complement mAbs. We have developed Affitins, a novel class of small artificial affinity proteins (7 kDa) derived from hyperthermophilic archaea. Affitins, selected from high-diversity libraries ([~]1012 variants) against any target protein, are highly stable, easy to engineer, and cost-effective to produce. Here, we developed a pipeline to generate Affitins in different multimerization formats targeting the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein through ribosome display selection and assessed their efficacy. The most potent candidates, dimerized or trimerized into 17-27 kDa proteins, displayed high thermal stability, strong binding affinities, and potent neutralization against various SARS-CoV-2 variants, with IC50 values as low as 32 pM. We also report the first hexameric Affitins, formed by dimerizing trimers through Fc fragment fusion ([~]106 kDa), achieving potent neutralization with an IC50 of 0.8 pM, ranking them among the most potent B1.351 SARS-Cov-2 neutralizing proteins. Our findings highlight Affitins as promising antiviral agents, demonstrating their versatility for engineering affinity proteins with higher valencies than that of antibodies while retaining a lower molecular weight, thereby expanding the toolkit for combating viral threats.

biochemistry↗

bioRxiv2024

Advantage of the F(ab)'2 fragment over IgG for RIT and PRIT

Radioimmunotherapy (RIT) has proved clinically effective in the treatment of relapsed or consolidating NHL after chemotherapy. However, it is still at the clinical trial stage for the treatment of solid tumors. The efficacy of the treatment on this type of tumor is limited by hematological toxicity, which restricts the activities injected. Pre-targeted radioimmunotherapy (PRIT) enables radiolabeling to be carried out in vivo at a time when the quantities of antigen-targeted vector reach a maximum level in the tumor, but have largely decayed in the bloodstream, thus limiting hematological toxicity. This therapeutic approach would make it possible to use higher radiopharmaceutical activities than those used in RIT, thereby increasing the doses deposited in the tumor and the therapeutic response. Despite encouraging preclinical trials, this approach has failed to live up to expectations in terms of clinical applications. In the context of PRIT using the Inverse Electron Demand Diels Alder (IEDDA) reaction as a method for radiolabeling tumor-targeted vectors, a major research effort has been made to improve the quality of in vivo radiolabeling using tetrazine (Tz) and transcycloctene (TCO) variants whose stability and reactivity have been optimized. Most trials in this field have been carried out using antibodies which, thanks to their long biological half-life, enable prolonged irradiation of tumors. Low-molecular-weight vectors such as affinity proteins or antigen-specific antibody fragments (VHH,scFv, F(ab)) have the advantage of being rapidly eliminated from circulation by renal filtration, but on the other hand, the quantities and residence times of these vectors in the tumor are reduced compared with IgG. F(ab)2 antibody fragments have properties intermediate between those of IgG and low-molecular-weight vectors that could be suitable for PRIT approaches, but they have not yet been evaluated in PRIT using IEDDA. In preparation for a preclinical trial of radioimmunotherapy of triple-negative breast cancer in spontaneously affected dogs, we compared the biodistribution of IgG and its F(ab)2 fragment targeting canine CD138 in a xenogeneic model of canine breast cancer and in a mouse model of colon cancer expressing human ACE antigen. This analysis shows that the use of F(ab)2 fragments improves the therapeutic index compared with IgG. F(ab)2 fragments seem particularly well suited to tumor targeting in PRIT using short-lived isotopes such as 211At.

cancer biology↗

bioRxiv2023

Antibacterial activity of human natural killer cells in the absence of accessory cells against extracellular Staphylococcus aureus and hypervirulent Pseudomonas aeruginosa bacteria

Natural killer (NK) cells play a crucial role in the innate immune response to bacterial infections, including those due to Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus). In vivo, it has been shown that NK cells are activated by innate accessory cells that detect the presence of bacteria and activate NK cells via a cytokine network. In vitro, several studies have shown that NK cells can also be activated without the help of accessory cells by direct contact with some bacteria species such as extracellular P. aeruginosa. Whether this phenomenon of direct activation is restricted to certain bacterial species, or whether it can be generalized, is still debated, as for example in the case of NK cell activation by S. aureus, which seems to require the intervention of accessory immune cells. Here, we show with co-incubation experiments between NK cells and two bacterial species, that, in the absence of accessory cells, NK cells are able to impede bacterial growth. This has been demonstrated for the P. aeruginosa PA14 strain, which is hypervirulent and known for its deleterious effects on NK cells, as well as for the S. aureus Newman strain. The monitoring of CD107a by flow cytometry suggests that NK cells degranulate after contact with S. aureus bacteria. Our study contributes to the idea that NK cells can be activated in the absence of any accessory cells by various species of bacteria, even an hypervirulent one, and therefore that NKs can directly have an antibacterial effect. This important insight may pave the way for new therapeutic approaches using antibacterial NK-cell engagers.

immunology↗