Impact of SARS-CoV-2 ORF6 and its variant polymorphisms on host responses and viral pathogenesis

: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) encodes several proteins that inhibit host interferon responses. Among these, ORF6 antagonizes interferon signaling by disrupting nucleocytoplasmic trafficking through interactions with the nuclear pore complex components Nup98-Rae1. However, the roles and contributions of ORF6 during physiological infection remain unexplored. We assessed the role of ORF6 during infection using recombinant viruses carrying a deletion or loss-of-function (LoF) mutation in ORF6. ORF6 plays key roles in interferon antagonism and viral pathogenesis by interfering with nuclear import and specifically the translocation of IRF and STAT transcription factors. Additionally, ORF6 inhibits cellular mRNA export, resulting in the remodeling of the host cell proteome, and regulates viral protein expression. Interestingly, the ORF6:D61L mutation that emerged in the Omicron BA.2 and BA.4 variants exhibits reduced interactions with Nup98-Rae1 and consequently impairs immune evasion. Our findings highlight the role of ORF6 in antagonizing innate immunity and emphasize the importance of studying the immune evasion strategies of SARS-CoV-2

Carbon-Based Solid-State Calcium Ion-Selective Microelectrode and Scanning Electrochemical Microscopy: A Quantitative Study of pH-Dependent Release of Calcium Ions from Bioactive Glass

Solid-state ion-selective electrodes are used as scanning electrochemical microscope (SECM) probes because of their inherent fast response time and ease of miniaturization. In this study, we report the development of a solid-state, low-poly­(vinyl chloride), carbon-based calcium ion-selective microelectrode (Ca²⁺-ISME), 25 μm in diameter, capable of performing an amperometric approach curve and serving as a potentiometric sensor. The Ca²⁺-ISME has a broad linear response range of 5 μM to 200 mM with a near Nernstian slope of 28 mV/log­[<i>a</i>_Ca²⁺]. The calculated detection limit for Ca²⁺-ISME is 1 μM. The selectivity coefficients of this Ca²⁺-ISME are log <i>K</i>_Ca²⁺_,A = −5.88, −5.54, and −6.31 for Mg²⁺, Na⁺, and K⁺, respectively. We used this new type of Ca²⁺-ISME as an SECM probe to quantitatively map the chemical microenvironment produced by a model substrate, bioactive glass (BAG). In acidic conditions (pH 4.5), BAG was found to increase the calcium ion concentration from 0.7 mM ([Ca²⁺] in artificial saliva) to 1.4 mM at 20 μm above the surface. In addition, a solid-state dual SECM pH probe was used to correlate the release of calcium ions with the change in local pH. Three-dimensional pH and calcium ion distribution mapping were also obtained by using these solid-state probes. The quantitative mapping of pH and Ca²⁺ above the BAG elucidates the effectiveness of BAG in neutralizing and releasing calcium ions in acidic conditions