Characterization of a mouse-adapted strain of bat severe acute respiratory syndrome-related coronavirus.

Bats carry genetically diverse severe acute respiratory syndrome-related coronaviruses (SARSr-CoVs). Some of them utilize human angiotensin-converting enzyme 2 (hACE2) as a receptor and cannot efficiently replicate in wild-type mice. Our previous study demonstrated that the bat SARSr-CoV rRsSHC014S induces respiratory infection and lung damage in hACE2 transgenic mice but not wild-type mice. In this study, we generated a mouse-adapted strain of rRsSHC014S, which we named SMA1901, by serial passaging of wild-type virus in BALB/c mice. SMA1901 showed increased infectivity in mouse lungs and induced interstitial lung pneumonia in both young and aged mice after intranasal inoculation. Genome sequencing revealed mutations in not only the spike protein but the whole genome, which may be responsible for the enhanced pathogenicity of SMA1901 in wild-type BALB/c mice. SMA1901 induced age-related mortality similar to that observed in SARS and COVID-19. Drug testing using antibodies and antiviral molecules indicated that this mouse-adapted virus strain can be used to test prophylactic and therapeutic drug candidates against SARSr-CoVs. IMPORTANCE The genetic diversity of SARSr-CoVs in wildlife and their potential risk of cross-species infection highlights the importance of developing a powerful animal model to evaluate the antibodies and antiviral drugs. We acquired the mouse-adapted strain of a bat-origin coronavirus named SMA1901 by natural serial passaging of rRsSHC014S in BALB/c mice. The SMA1901 infection caused interstitial pneumonia and inflammatory immune responses in both young and aged BALB/c mice after intranasal inoculation. Our model exhibited age-related mortality similar to SARS and COVID-19. Therefore, our model will be of high value for investigating the pathogenesis of bat SARSr-CoVs and could serve as a prospective test platform for prophylactic and therapeutic candidates.

Development of A MERS-CoV Replicon Cell Line for Antiviral Screening.

Middle East respiratory syndrome coronavirus (MERS-CoV) is the causative agent of a severe respiratory disease with a high mortality of ~ 35%. The lack of approved treatments for MERS-CoV infection underscores the need for a user-friendly system for rapid drug screening. In this study, we constructed a MERS-CoV replicon containing the Renilla luciferase (Rluc) reporter gene and a stable luciferase replicon-carrying cell line. Using this cell line, we showed that MERS-CoV replication was inhibited by combined application of lopinavir and ritonavir, indicating that this cell line can be used to screen inhibitors of MERS-CoV replication. Importantly, the MERS-replicon cell line can be used for high-throughput screening of antiviral drugs without the need for live virus handling, providing an effective and safe tool for the discovery of antiviral drugs against MERS-CoV.

Effect of ASO Blood Stasis Syndrome Serum on Vascular Endothelial Cell Injury and Regulation of Taohong Siwu Decoction on it / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To explore the effect of arteriosclerosis obliterans (ASO) blood stasis syndrome (BSS) serum on vascular endothelial cell injury and to study the regulation of Taohong Siwu Decoction (TSD) on it.</p><p><b>METHODS</b>Umbilical vein endothelial cell culture system was established. The serum endothelial cell injury model with ASO BSS was prepared. Low, medium, and high concentrations TSD containing serums were respectively added. The endothelial cell proliferation activity was observed by MTT method. Ultrastructures of endothelial cells were observed under transmission electron microscope. Changes of intracellular calcium ion concentration and the cytoskeleton were observed under laser confocal microscope. Contents of ET, NO, and transforming growth factor beta1 (TGF-beta1) in endothelial cell culture supernatant were detected by ELISA.</p><p><b>RESULTS</b>In ASO BSS serum group endothelial cell proliferation activities decreased, the cell structure was obviously destroyed, calcium ion concentration increased, contents of ET, NO and TGF-beta1 increased significantly (P < 0.01), and ET/NO ratio was imbalanced. After incubating with TSD drug containing serum, endothelial cell proliferation activities and injured cell structures were obviously improved; ET, NO and TGF-beta1 levels decreased (P < 0.05, P < 0.01), ET/NO ratios approximated to the normal level.</p><p><b>CONCLUSION</b>The main mechanism of TSD for treating ASO ASS lied in improving injured vascular endothelial cells and endocrine disorder.</p>

Construction of a non-infectious SARS coronavirus replicon for application in drug screening and analysis of viral protein function.

Severe acute respiratory syndrome virus (SARS-CoV) was the causative agent of the SARS outbreaks in 2002-2003. A safer in vitro system is desirable for conducting research on SARS-CoV and to screen for antiviral drugs against the virus. Based on the infectious cDNA clone of rSARS-CoV-DeltaE, in which the E gene has been deleted, a safe non-infectious replicon was constructed by replacing the S gene with the enhanced green fluorescent protein (eGFP) gene. Successful replication was achieved as evident from continuous expression of eGFP detected by both fluorescence and Western blot. Treatment with antiviral drugs demonstrated that the replication could be significantly inhibited by 0.4 mg/ml of cysteine proteinase inhibitor E-64D, but not by ribavirin. The same replicons containing further deletion of the coding regions for non-structural proteins (nsp) 1, 2 or 16 confirmed previous observation that nsp16, but not nsp1 or nsp2, was essential for efficient viral replication or transcription.