Mechanical tomography of an archaeal lemon-shaped virus reveals membrane-like fluidity of the capsid and liquid nucleoprotein cargo.

Archaeal lemon-shaped viruses have unique helical capsids composed of highly hydrophobic protein strands which can slide past each other resulting in remarkable morphological reorganization. Here, using atomic force microscopy, we explore the biomechanical properties of the lemon-shaped virions of Sulfolobus monocaudavirus 1 (SMV1), a double-stranded DNA virus which infects hyperthermophilic (~80 °C) and acidophilic (pH ~ 2) archaea. Our results reveal that SMV1 virions are extremely soft and withstand repeated extensive deformations, reaching remarkable strains of 80% during multiple cycles of consecutive mechanical assaults, yet showing scarce traces of disruption. SMV1 virions can reversibly collapse wall-to-wall, reducing their volume by ~90%. Beyond revealing the exceptional malleability of the SMV1 protein shell, our data also suggest a fluid-like nucleoprotein cargo which can flow inside the capsid, resisting and accommodating mechanical deformations without further alteration. Our experiments suggest a packing fraction of the virus core to be as low as 11%, with the amount of the accessory proteins almost four times exceeding that of the viral genome. Our findings indicate that SMV1 protein capsid displays biomechanical properties of lipid membranes, which is not found among protein capsids of other viruses. The remarkable malleability and fluidity of the SMV1 virions are likely necessary for the structural transformations during the infection and adaptation to extreme environmental conditions.

Use of quality indicators to compare point-of-care testing errors in a neonatal unit and errors in a STAT central laboratory.

BACKGROUND: Point-of-care testing (POCT), like other laboratory tests, can be affected by errors throughout the total testing process. To evaluate quality error rates, the use of quality indicators (QIs) is recommended; however, little information is available on the quality error rate associated with POCT. The objective of this study was to investigate quality error rates related to POCT and compare them with central laboratory (CL) testing. METHODS: We studied standardized QIs for POCT in comparison to CL testing. We compared error rates related to requests, collection, and handling of samples and results from external quality assessment program (EQAP) and internal quality control (IQC). RESULTS: The highest difference between POCT and CL testing was observed for QI related to patient identification, 45.3% vs. 0.02% (p<0.001). Regarding specimen collection and handling, the QI related to samples without results was also higher in POCT than in CL testing, 15.8% vs. 3.3% (p<0.001). For the QI related to insufficient sample volume, we obtained 2.9% vs. 0.9% (p=0.27). Unlike QIs for the preanalytical phase, QIs for the analytical phase had better results in POCT than CL testing. We obtained 8.3% vs. 16.6% (p=0.13) for QI related to unacceptable results in EQAP and 0.8% vs. 22.5% (p<0.001) for QI related to unacceptable results in IQC. CONCLUSIONS: Our results show that the preanalytical phase remains the main problem in POCT like in CL testing and that monitoring of quality indicators is a very valuable tool in reducing errors in POCT.

Surface characterization of alkane viral anchoring films prepared by titanate-assisted organosilanization.

Studies of virus adsorption on surfaces with optimized properties have attracted a lot of interest, mainly due to the influence of the surface in the retention, orientation and stability of the viral capsids. Besides, viruses in whole or in parts can be used as cages or vectors in different areas, such as biomedicine and materials science. A key requirement for virus nanocage application is their physical properties, i.e. their mechanical response and the distribution of surface charge, which determine virus-substrate interactions and stability. In the present work we show two examples of viruses exhibiting strong surface interactions on homogeneous hydrophobic surfaces. The surfaces were prepared by titanate assisted organosilanization, a sol-gel spin coating process, followed by a mild annealing step. We show by surface and interface spectroscopies that the process allows trapping triethoxy-octylsilane (OCTS) molecules, exhibiting a hydrophobic alkane rich surface finishing. Furthermore, the surfaces remain flat and behave as more efficient sorptive surfaces for virus particles than mica or graphite (HOPG). Also, we determine by atomic force microscopy (AFM) the mechanical properties of two types of viruses (human adenovirus and reovirus) and compare the results obtained on the OCTS functionalized surfaces with those obtained on mica and HOPG. Finally, the TIPT+OCTS surfaces were validated as platforms for the morphological and mechanical characterization of virus particles by using adenovirus as initial model and using HOPG and mica as standard control surfaces. Then, the same characteristics were determined on reovirus using TIPT+OCTS and HOPG, as an original contribution to the catalogue of physical properties of viral particles.

Monitoring SARS-CoV-2 Surrogate TGEV Individual Virions Structure Survival under Harsh Physicochemical Environments.

Effective airborne transmission of coronaviruses via liquid microdroplets requires a virion structure that must withstand harsh environmental conditions. Due to the demanding biosafety requirements for the study of human respiratory viruses, it is important to develop surrogate models to facilitate their investigation. Here we explore the mechanical properties and nanostructure of transmissible gastroenteritis virus (TGEV) virions in liquid milieu and their response to different chemical agents commonly used as biocides. Our data provide two-fold results on virus stability: First, while particles with larger size and lower packing fraction kept their morphology intact after successive mechanical aggressions, smaller viruses with higher packing fraction showed conspicuous evidence of structural damage and content release. Second, monitoring the structure of single TGEV particles in the presence of detergent and alcohol in real time revealed the stages of gradual degradation of the virus structure in situ. These data suggest that detergent is three orders of magnitude more efficient than alcohol in destabilizing TGEV virus particles, paving the way for optimizing hygienic protocols for viruses with similar structure, such as SARS-CoV-2.

Chaperonins: Nanocarriers with Biotechnological Applications.

Chaperonins are molecular chaperones found in all kingdoms of life, and as such they assist in the folding of other proteins. Structurally, chaperonins are cylinders composed of two back-to-back rings, each of which is an oligomer of ~60-kDa proteins. Chaperonins are found in two main conformations, one in which the cavity is open and ready to recognise and trap unfolded client proteins, and a "closed" form in which folding takes place. The conspicuous properties of this structure (a cylinder containing a cavity that allows confinement) and the potential to control its closure and aperture have inspired a number of nanotechnological applications that will be described in this review.

Sol-Gel-Deposited Ti-Doped ZnO: Toward Cell Fouling Transparent Conductive Oxides.

Ti-doped ZnO thin films were obtained with the aim of tailoring ZnO film bioadhesiveness and making the optoelectronic properties of ZnO materials transferable to biological environments. The films were prepared on silicon substrates by sol-gel spin-coating and subsequent annealing. A Ti-O segregation limits the ZnO crystallite growth and creates a buffer out-layer. Consequently, the Ti-doped ZnO presents slightly increased resistivity, which remains in the order of 10-3 Ω·cm. The strong biochemical interference of Zn2+ ions released from pure ZnO surfaces was evidenced by culturing Staphylococcus epidermidis with and without the Zn2+ coupling agent clioquinol. The Ti-doped ZnO surfaces showed a considerable increase of bacterial viability with respect to pure ZnO. Cell adhesion was assayed with human mesenchymal stem cells (hMSCs). Although hMSCs find difficulties to adhere to the pure ZnO surface, they progressively expand on the surface of ZnO when the Ti doping is increased. A preliminary microdevice has been built on the Si substrate with a ZnO film doped with 5% Ti. A one-dimensional micropattern with a zigzag structure shows the preference of hMSCs for adhesion on Ti-doped ZnO with respect to Si. The induced contrast of surface tension further induces a cell polarization effect on hMSCs. It is suggested that the presence of Ti-O covalent bonding on the doped surfaces provides a much more stable ground for bioadhesion. Such fouling behavior suggests an influence of Ti doping on film bioadhesiveness and sets the starting point for the selection of optimal materials for implantable optoelectronic devices.

Validación del proceso de fabricación de 2-[18]-fluoro-2-desoxi-D-glucosa / Production process validation of 2-[18F]-fluoro-2-deoxy-D-glucose

El objeto de la validación del proceso de fabricación de 2-[18F]-fluoro-2-desoxi-D-glucosa (FDG) fue demostrar: A) que los equipos y servicios implicados en dicho proceso estaban correctamente instalados, documentados y funcionaban adecuadamente y B) que la fabricación de FDG se realizaba de manera consistente y repetitiva de acuerdo con unos requisitos de calidad predefinidos. El documento básico de la validación fue el Plan Maestro de Validación, y las etapas fueron: cualificación de la instalación, cualificación del funcionamiento, cualificación del proceso, e informe de Validación. Una vez realizadas todas las verificaciones establecidas en los diferentes protocolos de cualificación, y no habiéndose encontrado desviaciones, se concluyó que el proceso podía considerarse validado, ya que se había realizado de forma consistente y repetitiva dentro de las especificaciones establecidas