Lipid nanoparticle-encapsulated mRNA antibody provides long-term protection against SARS-CoV-2 in mice and hamsters

Monoclonal antibodies represent important weapons in our arsenal to against the COVID-19 pandemic. However, this potential is severely limited by the time-consuming process of developing effective antibodies and the relative high cost of manufacturing. Herein, we present a rapid and cost-effective lipid nanoparticle (LNP) encapsulated-mRNA platform for in vivo delivery of SARS-CoV-2 neutralization antibodies. Two mRNAs encoding the light and heavy chains of a potent SARS-CoV-2 neutralizing antibody HB27, which is currently being evaluated in clinical trials, were encapsulated into clinical grade LNP formulations (named as mRNA-HB27-LNP). In vivo characterization demonstrated that intravenous administration of mRNA-HB27-LNP in mice resulted in a longer circulating half-life compared with the original HB27 antibody in protein format. More importantly, a single prophylactic administration of mRNA-HB27-LNP provided protection against SARS-CoV-2 challenge in mice at 1, 7 and even 63 days post administration. In a close contact transmission model, prophylactic administration of mRNA-HB27-LNP prevented SARS-CoV-2 infection between hamsters in a dose-dependent manner. Overall, our results demonstrate a superior long-term protection against SARS-CoV-2 conferred by a single administration of this unique mRNA antibody, highlighting the potential of this universal platform for antibody-based disease prevention and therapy against COVID-19 as well as a variety of other infectious diseases.Subject terms: Biological techniques, Immunology     

Sequential activation of phosphatidylinositol 3-kinase, beta Pix, Rac1, and Nox1 in growth factor-induced production of H2O2

The generation of reactive oxygen species (ROS) in cells stimulated with growth factors requires the activation of phosphatidylinositol 3-kinase (PI3K) and the Rac protein. We report here that the COOH-terminal region of Nox1, a protein related to gp91(phox) (Nox2) of phagocytic cells, is constitutively associated with beta Pix, a guanine nucleotide exchange factor for Rac. Both growth factor-induced ROS production and Rac1 activation were completely blocked in cells depleted of beta Pix by RNA interference. Rac1 was also shown to bind to the COOH-terminal region of Nox1 in a growth factor-dependent manner. Moreover, the depletion of Nox1 by RNA interference inhibited growth factor-induced ROS generation. These results suggest that ROS production in growth factor-stimulated cells is mediated by the sequential activation of PI3K, beta Pix, and Rac1, which then binds to Nox1 to stimulate its NADPH oxidase activity.     

<Emphasis Type="Italic">Thermobaculum terrenum</Emphasis> gen. nov., sp. nov.: a non-phototrophic gram-positive thermophile representing an environmental clone group related to the Chloroflexi (green non-sulfur bacteria) and Thermomicrobia

A novel bacterium was cultivated from an extreme thermal soil in Yellowstone National Park, Wyoming, USA, that at the time of sampling had a pH of 3.9 and a temperature range of 65–92 °C. This organism was found to be an obligate aerobic, non-spore-forming rod, and formed pink-colored colonies. Phylogenetic analysis of the 16S rRNA gene sequence placed this organism in a clade composed entirely of environmental clones most closely related to the phyla Chloroflexi and Thermomicrobia. This bacterium stained gram-positive, contained a novel fatty-acid profile, had cell wall muramic acid content similar to that of Bacillus subtilis (significantly greater than Escherichia coli), and failed to display a lipopolysaccharide profile in SDS-polyacrylamide gels that would be indicative of a gram-negative cell wall structure. Ultrastructure examinations with transmission electron microscopy showed a thick cell wall (approximately 34 nm wide) external to a cytoplasmic membrane. The organism was not motile under the culture conditions used, and electron microscopic examination showed no evidence of flagella. Genomic G+C content was 56.4 mol%, and growth was optimal at 67 °C and at a pH of 7.0. This organism was able to grow heterotrophically on various carbon compounds, would use only oxygen as an electron acceptor, and its growth was not affected by light. A new species of a novel genus is proposed, with YNP1^T (T=type strain) being Thermobaculum terrenum gen. nov., sp. nov. (16S rDNA gene GenBank accession AF391972). This bacterium has been deposited in the American Type Culture Collection (ATCC BAA-798) and the University of Oregon Culture Collection of Microorganisms from Extreme Environments (CCMEE 7001).     

Complicated and fatal Strongyloides infection in Canadians: risk factors,diagnosis and management

STRONGYLOIDIASIS, WHICH IS CAUSED by the nematode Strongyloides stercoralis, is a common and persistent infection, particularly in developing countries. In the setting of compromised cellular immunity, it can result in fulminant dissemination with case-fatality rates of over 70%. The majority of new Canadian immigrants come from countries where Strongyloides is highly endemic; therefore, the burden of Strongyloides may be underappreciated in Canada. Because early diagnosis and therapy can have a marked impact on disease outcome, screening for this infection should be considered mandatory for patients who have a history of travel or residence in a disease-endemic area and risk factors for disseminated disease (e.g., corticosteroid use and human T-lymphotropic virus type I infection). The following case is typical of a Strongyloides infection presenting to an infectious diseases service at a tertiary care hospital: A 50-year-old man who was originally from Cambodia but who had lived in Canada for the past 15 years presented with nausea and vomiting. His history was notable for arthritis, which was treated with prednisone, and type 2 diabetes mellitus. After admission, the patient became febrile and hypotensive. Blood cultures were positive for a gram-negative bacillus, and he was given ciprofloxacin and ceftriaxone. His respiratory status deteriorated, and Strongyloides larvae were incidentally noted on Gram stain and culture after bronchoalveolar lavage (Fig. 1). The patient was given 400 mg of albendazole twice a day and 15 mg of ivermectin once daily, but progressive respiratory failure followed and he died 3 weeks later.Open in a separate windowFig. 1: Strongyloides stercoralis larva tracks on a blood agar plate from the bronchoalveolar lavage of a patient with disseminated strongyloidiasis.This case exemplifies 2 key points. Foremost is that delays in establishing the diagnosis of strongyloidiasis can result in disseminated and fatal infection. Although the gastrointestinal tract is the primary site of Strongyloides infection, associated symptoms such as abdominal pain and intermittent diarrhea may be vague; if ignored by the clinician, the diagnosis may be made only upon dissemination and clinical deterioration of the patient. Second, eliciting an appropriate travel and migration history from patients and recognizing risk factors for disseminated infection are the essential epidemiologic clues for establishing early diagnosis. The purpose of this article is to highlight the risk factors and clinical presentation of strongyloidiasis and to provide a strategy for diagnosis and management. The goal is to raise awareness of this relatively common infection and thereby to facilitate early diagnosis and treatment of this potentially fatal but eminently curable disease.     

Moesin contributes an essential structural role in Drosophila photoreceptor morphogenesis

Ezrin-Radixin-Moesin (ERM) family proteins organize heterogeneous sub-plasma membrane protein scaffolds that shape membranes and their physiology. In Drosophila oocytes and imaginal discs, epithelial organization, fundamental to development and physiology, is devastated by the loss of Moesin. Here, we show that Moesin is crucial for Drosophila photoreceptor morphogenesis. Beyond its requirement for retinal epithelium integrity, Moesin is essential for the proper assembly of the apical membrane skeleton that builds the photosensitive membrane, the rhabdomere. Moesin localizes to the rhabdomere base, a dynamic locus of cytoskeletal reorganization and membrane traffic. Downregulation of Moesin through RNAi or genetic loss of function profoundly disrupts the membrane cytoskeleton and apical membrane organization. We find normal levels and distribution of Moesin in photoreceptors of a Moesin mutant previously regarded as protein null, suggesting alternative interpretations for studies using this allele. Our results show an essential structural role for Moesin in photoreceptor morphology.     

Phospholipase C-delta1 rescues intracellular Ca2+ overload in ischemic heart and hypoxic neonatal cardiomyocytes

Ischemia and simulated ischemic conditions cause intracellular Ca2+ overload in the myocardium. The relationship between ischemia injury and Ca2+ overload has not been fully characterized. The aim of the present study was to investigate the expression and characteristics of PLC isozymes in myocardial infarction-induced cardiac remodeling and heart failure. In normal rat heart tissue, PLC-delta1 (about 44 ng/mg of heart tissue) was most abundant isozymes compared to PLC-gamma1 (6.8 ng/mg) and PLC-beta1 (0.4 ng/mg). In ischemic heart and hypoxic neonatal cardiomyocytes, PLC-delta1, but not PLC-beta1 and PLC-gamma1, was selectively degraded, a response that could be inhibited by the calpain inhibitor, calpastatin, and by the caspase inhibitor, zVAD-fmk. Overexpression of the PLC-delta1 in hypoxic neonatal cardiomyocytes rescued intracellular Ca2+ overload by ischemic conditions. In the border zone and scar region of infarcted myocardium, and in hypoxic neonatal cardiomyocytes, the selective degradation of PLC-delta1 by the calcium sensitive proteases may play important roles in intracellular Ca2+ regulations under the ischemic conditions. It is suggested that PLC isozyme-changes may contribute to the alterations in calcium homeostasis in myocardial ischemia.