Nasal delivery of single-domain antibody improves symptoms of SARS-CoV-2 infection in an animal model.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes the disease COVID-19 can lead to serious symptoms, such as severe pneumonia, in the elderly and those with underlying medical conditions. While vaccines are now available, they do not work for everyone and therapeutic drugs are still needed, particularly for treating life-threatening conditions. Here, we showed nasal delivery of a new, unmodified camelid single-domain antibody (VHH), termed K-874A, effectively inhibited SARS-CoV-2 titers in infected lungs of Syrian hamsters without causing weight loss and cytokine induction. In vitro studies demonstrated that K-874A neutralized SARS-CoV-2 in both VeroE6/TMPRSS2 and human lung-derived alveolar organoid cells. Unlike other drug candidates, K-874A blocks viral membrane fusion rather than viral attachment. Cryo-electron microscopy revealed K-874A bound between the receptor binding domain and N-terminal domain of the virus S protein. Further, infected cells treated with K-874A produced fewer virus progeny that were less infective. We propose that direct administration of K-874A to the lung could be a new treatment for preventing the reinfection of amplified virus in COVID-19 patients.

Arabidopsis MBF1s control leaf cell cycle and its expansion.

Multiprotein bridging factor 1 (MBF1) is known as a transcriptional co-activator that enhances transcription of its target genes by bridging between transcription factors and TATA-box-binding protein in eukaryotes. Arabidopsis thaliana has three MBF1 genes: AtMBF1a-AtMBF1c. However, details of the functions of AtMBF1 remain unclear. For this study, transgenic Arabidopsis overexpressing AtMBF1 fused to an active transcriptional repression domain (SRDX) was constructed. The chimeric protein putatively functions as a transcriptional co-repressor and as a suppressor of functions of endogenous AtMBF1 in transgenic plants. Transgenic Arabidopsis overexpressing AtMBF1-SRDX (AtMBF1-SRDX(OE)) showed an extremely small leaf phenotype under a continuous white light condition. Its leaf cells-especially those around vascular tissues, where strong expression of endogenous AtMBF1s is observed-were much smaller than those from the wild type (WT). In addition, a lower cell number was observed in leaves from AtMBF1-SRDX(OE) plants. Time course analysis of cell size revealed that cell expansion of leaves of AtMBF1-SRDX(OE) plants was dramatically suppressed during the late leaf developmental stage (cell expansion stage), when endogenous AtMBF1b is strongly expressed in the WT. The results show that ploidy levels of leaves from AtMBF1-SRDX(OE) plants were dramatically lower than those from the WT; moreover, expression levels of several negative regulators of endoreduplication were more elevated in AtMBF1s-SRDX(OE) plants than those in the WT. These observations suggest that AtMBF1-SRDX interacts with regulators of endoreduplication. Therefore, AtMBF1s are considered to affect not only leaf cell expansion but also regulation of the ploidy level in leaf cells during the leaf expansion stage.

Direct determination of estrogenic and antiestrogenic activities using an enhanced plant two-hybrid system.

This paper reports a simple, low-cost, and extremely sensitive reporter-gene assay system for comprehensive analysis of estrogenic activity using transgenic Arabidopsis thaliana: the EPTH system. It had the capability to detect 17beta-estradiol at a concentration of 10 pM. The system was rendered 5 times more sensitive than a previous system [Tojo, T.; Tsuda, K.; Wada, T.; Yamazaki, K. Ecotoxicol. Environ. Saf. 2006, 64, 106-114) (1)] by increasing the copy number of the transactivation domain fused to a nuclear receptor co-activator. The system can efficiently detect other estrogenic and antiestrogenic substances. Estrogenic activities were determined in treated sewage samples from four distinct sewage farms using the system. Results showed that the system can detect estrogenic activity directly and more efficiently than a yeast two-hybrid system without any manipulation for extraction and condensation of hydrophobic compounds and aseptic treatment. Furthermore, the system also is useful as a powerful tool for discovery of a new category of natural estrogenic substances that are undetectable by previous plant and yeast systems.

A simple and extremely sensitive system for detecting estrogenic activity using transgenic Arabidopsis thaliana.

Numerous physiological processes are regulated by endocrine systems in animals. Endocrine-disrupting chemicals (EDCs) can affect physiological processes of organisms by binding to hormone receptors. Therefore, it is necessary to develop methods for detecting EDCs and removing them from the environment. We have developed a simple and low-cost reporter gene assay system for the comprehensive analysis of estrogenic activity using transgenic Arabidopsis thaliana. This transgenic plant constantly expresses two effector proteins: a chimeric estrogen receptor and a chimeric nuclear receptor coactivator. Estrogen-dependent interaction between the two effector proteins triggers transcriptional activation of reporter gene, beta-glucuronidase. We have demonstrated this transgenic plant's capability of detecting the existence of 17beta-estradiol at a concentration of 50 pM (13 pg/ml) in agar medium. This plant can also detect other estrogenic substances, such as diethylstilbestrol, p-n-nonylphenol, bisphenol A, and Genistein.