Oestreicher, J. | Search bioRxiv

bioRxiv2021

Serum Neutralizing Activity of mRNA-1273 against SARS-CoV-2 Variants

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has led to growing concerns over increased transmissibility and the ability of some variants to partially escape immunity. Sera from participants immunized on a prime-boost schedule with the mRNA-1273 COVID-19 vaccine were tested for neutralizing activity against several SARS-CoV-2 variants, including variants of concern (VOCs) and variants of interest (VOIs), compared to neutralization of the wild-type SARS-CoV-2 virus (designated as D614G). Results showed minimal effects on neutralization titers against the B.1.1.7 (Alpha) variant (1.2-fold reduction compared with D614G); other VOCs such as B.1.351 (Beta, including B.1.351-v1, B.1.351-v2, and B.1.351-v3), B.1.617.2 (Delta), and P.1 (Gamma) showed decreased neutralization titers ranging from 2.1-fold to 8.4-fold reductions compared with D614G, although all remained susceptible to mRNA-1273-elicited serum neutralization.

microbiology↗

bioRxiv2020

Real-time monitoring of subcellular H2O2 distribution in Chlamydomonas reinhardtii

H2O2 has been recognized as an important signaling molecule in plants. We sought to establish a genetically encoded, fluorescent H2O2 sensor that allows H2O2 monitoring in all major subcompartments of a Chlamydomonas cell. To this end we engineered the hypersensitive H2O2 sensor, roGFP2-Tsa2{Delta}CR, as a genetic part for the Chlamydomonas Modular Cloning toolbox. Using previously generated parts, together with new ones, we constructed modules and devices that target the sensor to the cytosol, nucleus, mitochondrial matrix, chloroplast stroma, thylakoid lumen, and ER. The sensor was functional in all compartments, except for the ER where it was fully oxidized. Employing our novel sensors, we show that H2O2 produced by photosynthetic linear electron transport (PET) in the stroma leaks into the cytosol but only reaches other subcellular compartments if produced under non-physiological conditions. Our results thus imply the establishment of steep intracellular H2O2 gradients under normal physiological conditions and suggest that the cytosolic complement of H2O2 scavenging enzymes effectively limits H2O2 diffusion. Furthermore, in heat stressed cells, we show that cytosolic H2O2 levels closely mirror temperature up- and downshifts and are independent from PET. We anticipate that these sensors will greatly facilitate future investigations into H2O2 biology in algal and plant cells.

plant biology↗