Evaluation of Rapid Lateral-Flow Tests Directed against the SARS-CoV-2 Nucleoprotein Using Viral Suspensions Belonging to Different Lineages of SARS-CoV-2

Within the successive waves that occurred during the SARS-CoV-2 pandemic, recommendations arose to test symptomatic and contact subjects by using rapid antigen devices directed against the viral nucleocapsid protein with the aim to isolate contagious patients without delay. The objective of this study was to evaluate the ability of four rapid lateral-flow tests (RLFT) that were commercially available on the French market in 2022 to recognize various strains of SARS-CoV-2. Series of five-fold dilutions of seven viral suspensions belonging to different lineages of SARS-CoV-2 (19A, 20A, Alpha, Beta, Gamma, Delta and Omicron) were used to evaluate the analytical sensitivity of four commercially available RLFTs (manufacturers: Abbott, AAZ, Becton-Dickinson and Biospeedia). Cell culture and quantitative RT-PCR were used as references. Excellent correlations were observed for each lineage strain between the viral titer obtained via cell culture and the number of RNA copies measured by quantitative RT-PCR. Although the four tests were able to recognize all the tested variants, significant differences in terms of sensitivity were observed between the four RLFTs. Despite the limitation represented by the small number of devices and clinical isolates that were tested, this study contributed by rapidly comparing the sensitivity of SARS-CoV-2 RLFTs in the Omicron era.     

The interleukin-1 receptor in normal and osteoarthritic human articular chondrocytes. Identification as the type I receptor and analysis of binding kinetics and biologic function

Objective. To identify and investigate the kinetic binding properties of interleukin-1 receptors (IL-1R), and examine the abilities of the 2 IL-1 isoforms to stimulate metalloprotease synthesis, in normal and osteoarthritic (OA) chondrocytes. Methods. Receptor affinity and density were determined using radioligand binding experiments and flow cytometry. Immunocytochemical analysis and affinity cross-linking studies were performed for characterization of IL-1R. Results. While no difference in receptor affinity between normal and OA chondrocytes was noted in binding studies (k_d ˜30 pM), a 2-fold increase in receptor density was found in OA chondrocytes as compared with normal chondrocytes (mean 4,069 sites/cell versus 2,315 sites/cell). Flow cytometry experiments also showed a significant increase in receptor density in OA cells, as well as an enhancement in the percentage of positive cells in diseased cartilage compared with normal. Binding data for both IL-1 isoforms revealed a single class of binding sites and receptor specificity. Factors such as IL-2, interferon-sγ, tumor necrosis factor α, and bovine insulin did not compete with IL-1β. By covalent ligand cross-linking and electrophoretic analysis, only type I IL-1R, a protein of 80 kd, was detected on chondrocytes. By immunocytochemical analysis, IL-1R was identified at the cell membrane level, in both normal and OA chondrocytes. The presence of nuclear staining was also observed, but only in OA chondrocytes. Recombinant human IL-1 (α and β) induced the secretion of stromelysin and collagenase in a dose-dependent manner. The IL-1 concentration required for half-maximal metalloprotease stimulation was 3–4 times lower in OA chondrocytes than in normal cells. Conclusion. These results indicate that OA chondrocytes have a higher sensitivity to the stimulation of metalloprotease synthesis by IL-1 than do normal cells. This could be related to the increased levels of IL-1R expressed in the OA cells. The implications of these findings with regard to the possible roles of IL-1 and IL-1R in the pathogenesis of OA are discussed.     

Double-Negative T Cell Levels Correlate with Chronic Graft-versus-Host Disease Severity

Chronic graft-versus-host disease (cGVHD) is a major complication, affecting 50% to 80% of long-term survivors of allogeneic hematopoietic stem cell transplantation. Current cGVHD therapies are neither specific nor curative, and patients are typically maintained for several months to years under immunosuppressive regimens that are associated with important side effects and increased susceptibility to life-threatening infections. As a result, continued investigation into the pathology of the disease and the search for novel diagnostic and therapeutic strategies to treat cGVHD remains a high priority. We report that the cellular dynamics of various immune cell subsets are related to cGVHD onset and severity in a cohort of allogeneic hematopoietic stem cell transplantation recipients. We document a decrease in the proportion of CD45RO⁺ CD4^?CD8^? (double-negative [DN]) T cells at the onset of cGVHD, a time at which serum levels of B cell activating factor and B cells are increased. We also find that DN T cell levels are correlated with cGVHD severity. Our present findings are in line with the view that activated DN T cells exhibit their immunoregulatory potential by eliminating B cells in vivo. Taken together, these findings suggest that maintaining elevated DN T cell numbers before the onset of cGVHD may prevent pathological B cell responses.     

One Health surveillance of West Nile and Usutu viruses: a repeated cross-sectional study exploring seroprevalence and endemicity in Southern France, 2016 to 2020

BackgroundWest Nile virus (WNV) and Usutu virus (USUV), two closely related flaviviruses, mainly follow an enzootic cycle involving mosquitoes and birds, but also infect humans and other mammals. Since 2010, their epidemiological situation may have shifted from irregular epidemics to endemicity in several European regions; this requires confirmation, as it could have implications for risk assessment and surveillance strategies.AimTo explore the seroprevalence in animals and humans and potential endemicity of WNV and USUV in Southern France, given a long history of WNV outbreaks and the only severe human USUV case in France in this region.MethodsWe evaluated the prevalence of WNV and USUV in a repeated cross-sectional study by serological and molecular analyses of human, dog, horse, bird and mosquito samples in the Camargue area, including the city of Montpellier, between 2016 and 2020.ResultsWe observed the active transmission of both viruses and higher USUV prevalence in humans, dogs, birds and mosquitoes, while WNV prevalence was higher in horses. In 500 human samples, 15 were positive for USUV and 6 for WNV. Genetic data showed that the same lineages, WNV lineage 1a and USUV lineage Africa 3, were found in mosquitoes in 2015, 2018 and 2020.ConclusionThese findings support existing literature suggesting endemisation in the study region and contribute to a better understanding of USUV and WNV circulation in Southern France. Our study underlines the importance of a One Health approach for the surveillance of these viruses.     

Modulation of the responses of human osteoblast-like cells to physiologic mechanical strains by biomaterial surfaces

In a previous study we demonstrated that MG-63 cells cultured on Ti-6Al-4V discs covered by alumina ceramic and submitted to intermittent mechanical strain (IMS) presented morphological alteration associated with enhanced differentiation. Here we examine how the mechanical response of osteoblasts can be modulated by the nature of the substrate. MG-63 cells were cultured on four materials: polystyrene and Ti-6Al-4V (average roughness = 0.48 microm) as smooth substrates; Ti-6Al-4V (average roughness = 5.76 microm) and Ti-6Al-4V covered with alumina (average roughness = 5.21 microm) as rough substrates. Mechanical strains were applied for 15 min, three times a day for 1-5 days with a 600 microstrains magnitude and a 0.25 Hz frequency. IMS stimulated alkaline phosphatase activity by 25-35% on all substrates and had no effect on cell growth on either substrate. Fibronectin (FN) was chosen as representative of cell-matrix interaction. FN production was increased by 60% after 1 day of stretching only on alumina-coated discs. FN organization examined on smooth substrates was affected by 5 days of IMS, showing a thickening of the fibres. The same modifications induced by IMS were previously observed on alumina-covered discs. Vinculin expression was not affected by IMS whatever the substrate. Cell-cell interactions were determined by N-cadherin immunoblotting. N-cadherin expression was increased by IMS specifically on rough substrates. Our results suggest that the nature of the surface did not influence the up-regulation of alkaline phosphatase activity induced by IMS, but modulates specifically cell-substrate as well as cell-cell interactions in response to IMS.