Study on the potential of Sanghuangporus sanghuang and its components as COVID-19 spike protein receptor binding domain inhibitors.

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and has led to the most severe global pandemic, which began in Wuhan, China. Angiotensin-converting enzyme 2 (ACE2) combines with the spike protein of SARS-CoV-2, allowing the virus to cross the membrane and enter the cell. SARS-CoV-2 is modified by the transmembrane protease serine 2 (TMPRSS2) to facilitate access to cells. Accordingly, ACE2 and TMPRSS2 are targets of vital importance for the avoidance of SARS-CoV-2 infection. Sanghuangporus sanghuang (SS) is a traditional Chinese medicine that has been demonstrated to have antitumor, antioxidant, anti-inflammatory, antidiabetic, hepatoprotective, neuroprotective and immunomodulatory properties. In this paper, we demonstrated that SS decreased ACE2 and TMPRSS2 expression in cell lines and a mouse model without cytotoxicity or organ damage. Liver and kidney sections were confirmed to have reduced expression of ACE2 and TMPRSS2 by immunohistochemistry (IHC) assessment. Then, hispidin, DBA, PAC, PAD and CA, phenolic compounds of SS, were also tested and verified to reduce the expression of ACE2 and TMPRSS2. In summary, the results indicate that SS and its phenolic compounds have latent capacity for preventing SARS-CoV-2 infection in the future.

Development and validation of an LC-MS/MS method for simultaneous determination of remdesivir and its hydrolyzed metabolite and nucleoside, and its application in a pharmacokinetic study of normal and diabetic nephropathy mice.

Remdesivir (RDV), a phosphoramidate prodrug, has broad-spectrum antiviral activity. It is the first antiviral drug approved by the US Food and Drug Administration (FDA) for the treatment of COVID-19. Remdesivir is rapidly metabolized in the body to produce derivatives: alanine metabolite (RM-442) and RDV C-nucleoside (RN). Here, the phosphatase inhibitor PhosSTOP and carboxylesterase inhibitor 5,5'-dithiobis-2-nitrobenzoic acid were used to improve stability of RDV in mouse blood. We developed a rapid and sensitive LC-MS/MS method to simultaneously quantify RDV, RM-442 and RN in mouse blood. Chromatographic separation was achieved by gradient elution on an Acquity HSS T3 column. The run time was 3.2 min. The linearity ranges of the analytes were 0.5-1,000 ng/ml for RDV and 5-10,000 ng/ml for both RM-442 and RN. The method had an acceptable precision (RSD < 8.4% for RDV, RSD < 10.7% for RM-442 and RSD < 7.2% for RN) and accuracy (91.0-106.3% for RDV, 92.5-98.6% for RM-442 and 87.5-98.4% for RN). This method was successfully applied to analyze RDV, RM-442 and RN in the blood of normal and diabetic nephropathy DBA/2 J mice after intravenous injection of RDV at 20 mg/kg. The area under the concentration-time curve of RN between the normal and diabetic nephropathy mice showed a significant difference (P < 0.01).

Efficient targeted transgenesis of large donor DNA into multiple mouse genetic backgrounds using bacteriophage Bxb1 integrase.

The development of mouse models of human disease and synthetic biology research by targeted transgenesis of large DNA constructs represent a significant genetic engineering hurdle. We developed an efficient, precise, single-copy integration of large transgenes directly into zygotes using multiple mouse genetic backgrounds. We used in vivo Bxb1 mediated recombinase-mediated cassette exchange (RMCE) with a transgene "landing pad" composed of dual heterologous Bxb1 attachment (att) sites in cis, within the Gt(ROSA)26Sor safe harbor locus. RMCE of donor was achieved by microinjection of vector DNA carrying cognate attachment sites flanking the donor transgene with Bxb1-integrase mRNA. This approach achieves perfect vector-free integration of donor constructs at efficiencies > 40% with up to ~ 43 kb transgenes. Coupled with a nanopore-based Cas9-targeted sequencing (nCATS), complete verification of precise insertion sequence was achieved. As a proof-of-concept we describe the development of C57BL/6J and NSG Krt18-ACE2 models for SARS-CoV2 research with verified heterozygous N1 animals within ~ 4 months. Additionally, we created a series of mice with diverse backgrounds carrying a single att site including FVB/NJ, PWK/PhJ, NOD/ShiLtJ, CAST/EiJ and DBA/2J allowing for rapid transgene insertion. Combined, this system enables predictable, rapid development with simplified characterization of precisely targeted transgenic animals across multiple genetic backgrounds.

Genetic Dissection of the Regulatory Mechanisms of Ace2 in the Infected Mouse Lung.

Acute lung injury (ALI) is an important cause of morbidity and mortality after viral infections, including influenza A virus H1N1, SARS-CoV, MERS-CoV, and SARS-CoV-2. The angiotensin I converting enzyme 2 (ACE2) is a key host membrane-bound protein that modulates ALI induced by viral infection, pulmonary acid aspiration, and sepsis. However, the contributions of ACE2 sequence variants to individual differences in disease risk and severity after viral infection are not understood. In this study, we quantified H1N1 influenza-infected lung transcriptomes across a family of 41 BXD recombinant inbred strains of mice and both parents-C57BL/6J and DBA/2J. In response to infection Ace2 mRNA levels decreased significantly for both parental strains and the expression levels was associated with disease severity (body weight loss) and viral load (expression levels of viral NA segment) across the BXD family members. Pulmonary RNA-seq for 43 lines was analyzed using weighted gene co-expression network analysis (WGCNA) and Bayesian network approaches. Ace2 not only participated in virus-induced ALI by interacting with TNF, MAPK, and NOTCH signaling pathways, but was also linked with high confidence to gene products that have important functions in the pulmonary epithelium, including Rnf128, Muc5b, and Tmprss2. Comparable sets of transcripts were also highlighted in parallel studies of human SARS-CoV-infected primary human airway epithelial cells. Using conventional mapping methods, we determined that weight loss at two and three days after viral infection maps to chromosome X-the location of Ace2. This finding motivated the hierarchical Bayesian network analysis, which defined molecular endophenotypes of lung infection linked to Ace2 expression and to a key disease outcome. Core members of this Bayesian network include Ace2, Atf4, Csf2, Cxcl2, Lif, Maml3, Muc5b, Reg3g, Ripk3, and Traf3. Collectively, these findings define a causally-rooted Ace2 modulatory network relevant to host response to viral infection and identify potential therapeutic targets for virus-induced respiratory diseases, including those caused by influenza and coronaviruses.

Difluoromethylornithine (DFMO), an Inhibitor of Polyamine Biosynthesis, and Antioxidant N-Acetylcysteine Potentiate Immune Response in Mice to the Recombinant Hepatitis C Virus NS5B Protein.

Hepatitis C virus (HCV) is one of the main triggers of chronic liver disease. Despite tremendous progress in the HCV field, there is still no vaccine against this virus. Potential vaccines can be based on its recombinant proteins. To increase the humoral and, especially, cellular immune response to them, more effective adjuvants are needed. Here, we evaluated a panel of compounds as potential adjuvants using the HCV NS5B protein as an immunogen. These compounds included inhibitors of polyamine biosynthesis and urea cycle, the mTOR pathway, antioxidants, and cellular receptors. A pronounced stimulation of cell proliferation and interferon-γ (IFN-γ) secretion in response to concanavalin A was shown for antioxidant N-acetylcysteine (NAC), polyamine biosynthesis inhibitor 2-difluoromethylornithine (DFMO), and TLR9 agonist CpG ODN 1826 (CpG). Their usage during the immunization of mice with the recombinant NS5B protein significantly increased antibody titers, enhanced lymphocyte proliferation and IFN-γ production. NAC and CpG decreased relative Treg numbers; CpG increased the number of myeloid-derived suppressor cells (MDSCs), whereas neither NAC nor DFMO affected MDSC counts. NAC and DFMO suppressed NO and interleukin 10 (IL-10) production by splenocytes, while DFMO increased the levels of IL-12. This is the first evidence of immunomodulatory activity of NAC and DFMO during prophylactic immunization against infectious diseases.

A SARS-CoV-2 Infection Model in Mice Demonstrates Protection by Neutralizing Antibodies.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a pandemic with millions of human infections. One limitation to the evaluation of potential therapies and vaccines to inhibit SARS-CoV-2 infection and ameliorate disease is the lack of susceptible small animals in large numbers. Commercially available laboratory strains of mice are not readily infected by SARS-CoV-2 because of species-specific differences in their angiotensin-converting enzyme 2 (ACE2) receptors. Here, we transduced replication-defective adenoviruses encoding human ACE2 via intranasal administration into BALB/c mice and established receptor expression in lung tissues. hACE2-transduced mice were productively infected with SARS-CoV-2, and this resulted in high viral titers in the lung, lung pathology, and weight loss. Passive transfer of a neutralizing monoclonal antibody reduced viral burden in the lung and mitigated inflammation and weight loss. The development of an accessible mouse model of SARS-CoV-2 infection and pathogenesis will expedite the testing and deployment of therapeutics and vaccines.