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International audience; Current solutions for bacteria and viruses identification are based on time-consuming technics with complex preparation procedures. In the present work, we revealed label-free the presence of free viral particles and bacteria with a computational two-photon fluorescence (C-TPF) strategy. Six bacteria were tested: Escherichia coli, Staphylococcus epidermidis, Proteus vulgaris, Pseudomonas fluorescens, Bacillus subtilis and Clostridium perfringens. The two families of viral particles were the herpes virus with the cytomegalovirus (CMV, 300 nm of diameter) and the coronavirus with the SARS-CoV-2 (100 nm of diameter). The instrumental and computational pipeline FAMOUS optimized the produced 3D images. The origin of the fluorescence emission was discussed for bacteria regarding to their two-photon excitation spectra and attributed to the metabolic indicators (FAD and NADH). The optical and computational strategy constitute a new approach for imaging label-free viral particles and bacteria and paves the way to a new understanding of viral or bacterial ways of infection.

La compréhension des modes d’actions biologiques des virus dans une cellule hôte est un sujet complexe pour lequel nous pensons que les solutions optiques pourraient apporter des éléments de réponse nouveaux. Cependant, les dimensions des particules virales sont environ 3 fois plus petites que la résolution d’un microscope optique. Nous proposons de tester une nouvelle stratégie instrumentale et computationnelle, reposant sur la microscopie multiphotonique, pour visualiser des objets dont les dimensions sont de l’ordre de quelques centaines de nanomètres. Cette stratégie repose sur la prise en compte de la réponse impulsionnelle de l’instrument (PSF pour Point Spread Function) in situ, modélisée mathématiquement. A partir de ce modèle qui prend en compte les distorsions optiques locales, un post-traitement numérique des images est appliqué en vue d’optimiser la qualité visuelle des images. Nous faisons des tests sur deux populations de virus : les Cytomégalovirus (CMV) et le SARS-CoV-2.

Viruses are unseen enemies which tend to disarmingly spread from person-to-person, therefore causing health damages and weakens the immunity system. Their invisibility give rise to various representations, projections and imaginations that allow laypeople to tame the unseen and intangible nature of viruses. For the first time to our knowledge, we are proposing a novel and uncommon scientific approach resting on the synergy between two scientific field: Technical Sciences & Medicine (TSM) with Social Sciences and Humanities (SSH). Therefore, we present the results of our investigations concerning the evaluation of the social impact of the scientific image of free virions on a specific population, particularly affected by the Covid-19 pandemic: people over 60 years old. For this research, we have implemented two scientific imaging solutions to visualize the free viral particles of SARS-CoV-2. The first one is a standard solution of electron microscopy and the second one is an optical and computational solution of microscopy. The scientific representations of SARS-CoV-2 that we have proposed is in fact highly different from the mass media image that we can see everywhere. Concerning the targeted population, we have demonstrated that the scientific image has a negative impact on the population. Thus, the socially constructed representations of these invisible enemies have a preponderant role in driving laypeople's emotional reactions and health-related behaviors. Therefore, imaging viruses remains a critical scientific effort that contributes irrevocably to alleviate laypeople's misrepresentations of these invisible enemies.

International audience; In a medical use, ultrastructure of muscle is currently revealed by images of resected samples achieved thanks to Electron Microscopy (EM), requiring freezing and paraffin sections, with a set of histological, molecular and biochemical analyses. The resection, slicing and labelling steps cause an alteration of the phenotypic and volumetric information compared to their initial integrity. Starting from this statement, we have developed an original pipeline resting on the imbrication of an optical and computational strategy for imaging 3D biomedical structures without resorting to slicing, freezing and labelling steps. The assembly of myosin of a whole muscle is revealed thanks to the second harmonic generation (SHG) recorded with a multiphoton microscope, all along the entire 180 µm of thickness of the Extensor digitorum longus (EDL) of a wild mouse. During the SHG recording, the Point-Spread-Function (PSF) of the multiphoton microscope is recorded all along the imaging depth. This step highlights an axial broadening of the PSF while maintaining a constant planar PSF throughout the whole depth of the recordings. Then, a fitting algorithm estimated a mathematical model of the PSF, highlighting its variability into the whole image depth. Finally, a computational image restauration is led thanks to the fast image deblurring algorithm BD3MG accounting for the depth variant PSF. The non-stationary distortions all along the recorded image is employed thus correcting accurately the image distortion. The axial organization of the myosin is revealed for the first time, highlighting tubular organization of myosin into the myofibrils.

International audience; The complexity of the COVID-19 pandemic reveals important methodological debates and challenges with regard to the articulation of different research disciplines. The current COVID-19 societal research highlights the need for a holistic study of the COVID-19 pandemic issues based on a multidisciplinary research approach. The multidisciplinary approach appears to be essential to seize the invisible enemy of SARS-CoV-2 virus and related “domino effect” of consequences. In this article, we propose concrete avenues of reflection, drawn on innovative approaches of collective intelligence and co-design. Indeed, these approaches allow to initiate a logic of cross-fertilization of different disciplines by positioning the object of the study at the center of concerns of each of these disciplines. It is from this cross-fertilization that the CoviZion project will be able to evolve from a multidisciplinary device to an interdisciplinary or even transdisciplinary device allowing a 360-degree reading of the complex and unprecedented societal situation that is the COVID-19 crisis. This transdisciplinary approach is essential and has important implications, such as providing tools for better efficiency in the sanitary crisis management, particularly through public health policies.; La complexité de la pandémie de COVID-19 révèle d’importants débats méthodologiques et des défis quant à l’articulation de différentes approches de recherche. La recherche sociétale actuelle concernant la COVID-19 met en évidence la nécessité d'une étude holistique de la situation de la pandémie de COVID-19, fondée sur une approche de recherche multidisciplinaire. L'approche multidisciplinaire apparaît indispensable pour saisir l'ennemi invisible qu’est le virus SARS-COV-2 et ses conséquences sociétales à « l’effet domino ». Dans cet article, nous proposons des pistes de réflexion concrètes qui s’appuient sur les approches méthodologiques de l’intelligence collective et de co-design. En effet, celles-ci permettent d’engager une logique de fertilisation croisée des disciplines en positionnant l’objet d’étude au centre des préoccupations de chacune des disciplines convoquées. C’est à partir de cette fertilisation croisée que le projet CoviZion pourra évoluer en passant d’un dispositif multidisciplinaire à un dispositif interdisciplinaire voire transdisciplinaire permettant une lecture à 360 degrés de la situation sociétale complexe et inédite qu’est la crise COVID-19. Cette approche transdisciplinaire est essentielle et connaît des implications importantes, notamment celle de fournir des outils permettant une meilleure efficacité dans la gestion des crises sanitaires par les politiques de santé publiques particulièrement.