[Intervention of the medical-psychological emergency unit with the carers during Covid-19]. / Intervention de la cellule d'urgence médico-psychologique auprès des soignants pendant la Covid-19.

The medical-psychological emergency units have been meeting with care teams to discuss their experiences and feelings about Covid-19 for a little over a year. This preventive approach allows for psycho-education and the identification of stressful states.

The thermostability of the RTS,S/AS01 malaria vaccine can be increased by co-lyophilizing RTS,S and AS01.

BACKGROUND: Developing thermostable vaccines is a challenge for pharmaceutical companies due to the inherent instability of biological molecules in aqueous solution. The problem is even more stringent in regions subjected to high temperatures in which protective cold chain is difficult to maintain due to a lack of infrastructure. Here, a simple, cost-effective solution to increase the thermostability of the malaria candidate vaccine RTS,S/AS01 is described. This vaccine currently needs to be stored between 2 and 8  °C due to the sensitivity of liquid AS01 to higher temperatures. The strategy was to increase thermostability by co-lyophilizing the RTS,S antigen and AS01. METHODS: Co-lyophilization was achieved in a solution containing 5% sucrose, 10 mM potassium phosphate and 0.0312% polysorbate 80 at pH 6.1. The physicho-chemical characteristics and immunogenic properties of the resulting solid product, called CL-vac, fresh or stored at high temperature, were compared to those of the candidate RTS,S/AS01. RESULTS: CL-vac proved to be acceptable in terms of visual appearance and physico-chemical characteristics. The structural integrity of both RTS,S and AS01 within CL-vac and its equivalence to the RTS,S/AS01 candidate vaccine were shown. Further, the stability of CL-vac was demonstrated for storage periods including 1 year at 4  °C, 1 year at 30  °C, and up to 6 months at 37  °C. In addition, CL-vac could withstand a heat excursion consisting of 1 month at 45  °C after storage for 1 year at 30  °C. Equivalence and stability were demonstrated by the various analytical tools and the immunogenicity of the samples after storage was also demonstrated in mice. CONCLUSIONS: In conclusion, the co-lyophilization process appeared as a promising approach to increase RTS/AS01 vaccine thermostability.

Mechanisms of Antigen Adsorption Onto an Aluminum-Hydroxide Adjuvant Evaluated by High-Throughput Screening.

The adsorption mechanism of antigen on aluminum adjuvant can affect antigen elution at the injection site and hence the immune response. Our aim was to evaluate adsorption onto aluminum hydroxide (AH) by ligand exchange and electrostatic interactions of model proteins and antigens, bovine serum albumin (BSA), ß-casein, ovalbumin (OVA), hepatitis B surface antigen, and tetanus toxin (TT). A high-throughput screening platform was developed to measure adsorption isotherms in the presence of electrolytes and ligand exchange by a fluorescence-spectroscopy method that detects the catalysis of 6,8-difluoro-4-methylumbelliferyl phosphate by free hydroxyl groups on AH. BSA adsorption depended on predominant electrostatic interactions. Ligand exchange contributes to the adsorption of ß-casein, OVA, hepatitis B surface antigen, and TT onto AH. Based on relative surface phosphophilicity and adsorption isotherms in the presence of phosphate and fluoride, the capacities of the proteins to interact with AH by ligand exchange followed the trend: OVA < ß-casein < BSA < TT. This could be explained by both the content of ligands available in the protein structure for ligand exchange and the antigen's molecular weight. The high-throughput screening platform can be used to better understand the contributions of ligand exchange and electrostatic attractions governing the interactions between an antigen adsorbed onto aluminum-containing adjuvant.

[A listening support group for nursing staff]. / Une cellule d'écoute et de soutien pour les personnels soignants.

The feedback from a consultant nurse in a listening support group for health professionals shows that, for hospital nursing staff, the phenomenon of suffering in the workplace is a reality. In addition to providing help to professionals who request it, the missions of such a group are to promote discussion around psycho-social risks in the framework of a policy of compassionate care for staff.

Automated Gravimetric Calibration to Optimize the Accuracy and Precision of TECAN Freedom EVO Liquid Handler.

High-throughput screening technologies are increasingly integrated into the formulation development process of biopharmaceuticals. The performance of liquid handling systems is dependent on the ability to deliver accurate and precise volumes of specific reagents to ensure process quality. We have developed an automated gravimetric calibration procedure to adjust the accuracy and evaluate the precision of the TECAN Freedom EVO liquid handling system. Volumes from 3 to 900 µL using calibrated syringes and fixed tips were evaluated with various solutions, including aluminum hydroxide and phosphate adjuvants, ß-casein, sucrose, sodium chloride, and phosphate-buffered saline. The methodology to set up liquid class pipetting parameters for each solution was to split the process in three steps: (1) screening of predefined liquid class, including different pipetting parameters; (2) adjustment of accuracy parameters based on a calibration curve; and (3) confirmation of the adjustment. The run of appropriate pipetting scripts, data acquisition, and reports until the creation of a new liquid class in EVOware was fully automated. The calibration and confirmation of the robotic system was simple, efficient, and precise and could accelerate data acquisition for a wide range of biopharmaceutical applications.

Development of a high-throughput screening platform to study the adsorption of antigens onto aluminum-containing adjuvants.

Aluminum-containing salts are important adjuvants in the formulations of many licensed human vaccines. However, in the early stage of the design of a new vaccine, a thorough understanding of the adsorption mechanisms of an antigen onto an aluminum salt is required. Therefore, we have developed a robust, rapid, and reproducible high-throughput screening (HTS) platform to study the adsorption capacity of aluminum-containing vaccines. The adsorption isotherms on aluminum hydroxide and aluminum phosphate of two model proteins, ß-casein, and bovine serum albumin, were evaluated using a liquid handling system, which permitted rapid sample preparation in a small volume without nonspecific adsorption. Highly reproducible adsorption capacities and adsorptive coefficients were estimated based on the Langmuir model. To demonstrate the potential of this HTS platform, we evaluated the adsorption isotherms for two antigens, hepatitis B surface antigen and a pneumococcal serotype polysaccharide conjugated to a protein-D carrier, onto aluminum-containing vaccines at either a constant protein or a constant aluminum concentration. The automated assay enabled the rapid quantification of antigen adsorption with a significant reduction in operator workload and reagent use. This platform should accelerate data acquisition during the development of a new vaccine.

[A support unit and relaxation area for caregivers]. / Une cellule d'écoute et un espace ressource pour les soignants.

A confidential and anonymous support unit, led by a nurse and a psychologist, has been created for caregivers within a hospital. It also has a relaxation area where they can learn different relaxation techniques. The aim of these places is to promote workers' wellbeing and prevent psychosocial risks.

High-throughput assessment of antigen conformational stability by ultraviolet absorption spectroscopy and its application to excipient screening.

In high-throughput screening (HTS) assays, the use of ultraviolet absorption spectroscopy (UA) is commonly limited to concentration and turbidity measurements. Our aim was to evaluate microplate-based UA and its second-derivative [(2d)UA] for measuring the conformational stability of two recombinant antigenic proteins in the presence of 44 excipients. Protein conformational stability was assessed by (2d)UA upon titration with guanidine hydrochloride. (2d)UA was compared with tryptophan fluorescence spectroscopy (TF) and differential scanning fluorimetry (DSF), both commonly used techniques for measuring protein conformational stability. The HTS data were corrected for plate, row and column effects by applying a median polish procedure. Irrespective of the unfolding method applied, similar stabilizing excipients were identified by all analytical methods for a given antigen. The native forms of both antigens were destabilized by arginine, hydroxypropyl-ß-cyclodextrin, and sodium docusate, and were protected by polyols. The median polish correction improved the quality of the prediction models and the screening resolution. The higher sensitivities of TF and DSF compared with (2d)UA allowed the identification of a larger number of stabilizing excipients. However, similar screening resolutions (z'-factor > 0.8) were observed for 2dUA, TF, and DSF in a HTS of excipients applied to one of the antigens. Therefore, (2d)UA deserves more attention in HTS studies focused on protein conformational stability.

High-throughput screening of excipients intended to prevent antigen aggregation at air-liquid interface.

PURPOSE: The aim was to develop a high-throughput screening method compatible with low protein concentrations, as present in vaccines, in order to evaluate the performance of various excipients in preventing the aggregation at air-liquid interface of an experimental recombinant antigen called Antigen 18A. METHODS: Aggregation of Antigen 18A was triggered by shaking in a half-filled vial or by air bubbling in a microplate. Size-exclusion chromatography, turbidimetry, Nile Red fluorescence spectroscopy, and attenuated total reflection Fourier-transform infrared spectroscopy were used to assess Antigen 18A aggregation. A high-throughput method, based on tryptophan fluorescence spectroscopy, was set up to screen excipients for their capability to prevent Antigen 18A aggregation at air-liquid interface. RESULTS: While a similar aggregation profile was obtained with both stress tests when using size-exclusion chromatography, spectroscopic and turbidimetric methods showed an influence of the stress protocol on the nature of the aggregates. The high-throughput screening revealed that 7 out of 44 excipients significantly prevented Antigen 18A from aggregating. We confirmed the performance of hydroxypropyl-ß-cyclodextrin and hydroxypropyl-γ-cyclodextrin, as well as poloxamers 188 and 407, in half-filled shaken vials. CONCLUSIONS: A high-throughput screening approach can be followed for evaluating the performance of excipients against aggregation of a protein antigen at air-liquid interface.