Background:The precise insertion of large DNA fragments(>3–5 kb)remains one of the key obstacles in establishment of genetically modified murine models.Methods:A 21 kb large DNA fragment containing three tandemly ...Background:The precise insertion of large DNA fragments(>3–5 kb)remains one of the key obstacles in establishment of genetically modified murine models.Methods:A 21 kb large DNA fragment containing three tandemly linked copies of the human HRAS gene was inserted into the genome of C57BL/6J mouse,generating a mouse model designated as KI.C57-ras(or named NF-h HRAS).Whole-genome sequencing and Sanger sequencing were utilized to it confirm precise insertion and copy number.The stability of transgene expression among different generations was verified from multiple aspects using by digital PCR,western blot and DNA sequencing.To assess tumor susceptibility in the mouse model,N-Nitroso-N-methylurea(MNU)was administered at a dosage of 75 mg/kg.Histopathological examinations were conducted using hematoxylin and eosin(H&E)staining.Results:The HRAS DNA fragment was inserted into mouse chromosome 15E1 site,locating between 80623202 bp and 80625020 bp.NF-h HRAS mice exhibited stable inheritance and displayed consistent phenotypes across individuals.Moreover,this mouse model exhibited a high susceptibility to carcinogens.Upon administration of MNU the earliest mortality onset was earlier than that of wild-type littermates(day 65 vs.day 78 for male and day 56 vs.day 84 for female).Notably,100%of the NF-h HRAS transgenic mice developed tumors,with approximately 84%of male NF-h HRAS mice exhibiting specific tumor types,such as squamous cell carcinoma or squamous cell papilloma,which was consistent with the previously reported carcinogenic rasH2 mouse model.The types of tumors and the target organs exhibited diversity in NFh HRAS mice,while the spontaneous tumor incidence remained low(1/50).Conclusions:The NF-h HRAS mice demonstrated excellent genetic stability,a reproducible phenotype,and high susceptibility to carcinogens,indicating their potential utility in non-clinical safety evaluations of drugs as per the S1B guidelines issued by the ICH(The International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use).展开更多
Dear Editor,Since the outbreak of COVID-19 at the end of 2019,its causative agent SARS-Co V-2 has been spreading around the world for one and half a year.During the long global circulation of SARS-Co V-2,mutations in ...Dear Editor,Since the outbreak of COVID-19 at the end of 2019,its causative agent SARS-Co V-2 has been spreading around the world for one and half a year.During the long global circulation of SARS-Co V-2,mutations in the viral genome gradually emerged and accumulated。展开更多
COVID-19,caused by SARS-CoV-2,is the most consequential pandemic of this century.Since the outbreak in late 2019,animal models have been playing crucial roles in aiding the rapid development of vaccines/drugs for prev...COVID-19,caused by SARS-CoV-2,is the most consequential pandemic of this century.Since the outbreak in late 2019,animal models have been playing crucial roles in aiding the rapid development of vaccines/drugs for prevention and therapy,as well as understanding the pathogenesis of SARS-CoV-2 infection and immune responses of hosts.However,the current animal models have some deficits and there is an urgent need for novel models to evaluate the virulence of variants of concerns(VOC),antibodydependent enhancement(ADE),and various comorbidities of COVID-19.This review summarizes the clinical features of COVID-19 in different populations,and the characteristics of the major animal models of SARS-CoV-2,including those naturally susceptible animals,such as non-human primates,Syrian hamster,ferret,minks,poultry,livestock,and mouse models sensitized by genetically modified,AAV/adenoviral transduced,mouse-adapted strain of SARS-CoV-2,and by engraftment of human tissues or cells.Since understanding the host receptors and proteases is essential for designing advanced genetically modified animal models,successful studies on receptors and proteases are also reviewed.Several improved alternatives for future mouse models are proposed,including the reselection of alternative receptor genes or multiple gene combinations,the use of transgenic or knock-in method,and different strains for establishing the next generation of genetically modified mice.展开更多
Dear Editor,The COVID-19 pandemic has covered more than 200 countries and regions around the world since its outbreak in January 2020.To date,the SARS-CoV-2 virus has caused>1.2 million deaths.The mortality rate of...Dear Editor,The COVID-19 pandemic has covered more than 200 countries and regions around the world since its outbreak in January 2020.To date,the SARS-CoV-2 virus has caused>1.2 million deaths.The mortality rate of COVID-19 is closely concerned with the clinical symptoms of the patients from mild-to-severe disease.Notably,in its most severe form,COVID-19 leads to life-threatening pneumonia and acute respiratory distress syndrome(ARDS),which is mostly accom-panied by a hyperactive immune response called"cytokine storm"and has high death rates from 40 to 50%.展开更多
Neutrophil extracellular traps(NETs)can capture and kill viruses,such as influenza viruses,human immunodeficiency virus(HIV),and respiratory syncytial virus(RSV),thus contributing to host defense.Contrary to our expec...Neutrophil extracellular traps(NETs)can capture and kill viruses,such as influenza viruses,human immunodeficiency virus(HIV),and respiratory syncytial virus(RSV),thus contributing to host defense.Contrary to our expectation,we show here that the histones released by NETosis enhance the infectivity of SARS-CoV-2,as found by using live SARS-CoV-2 and two pseudovirus systems as well as a mouse model.The histone H3 or H4 selectively binds to subunit 2 of the spike(S)protein,as shown by a biochemical binding assay,surface plasmon resonance and binding energy calculation as well as the construction of a mutant S protein by replacing four acidic amino acids.Sialic acid on the host cell surface is the key molecule to which histones bridge subunit 2 of the S protein.Moreover,histones enhance cell-cell fusion.Finally,treatment with an inhibitor of NETosis,histone H3 or H4,or sialic acid notably affected the levels of sgRNA copies and the number of apoptotic cells in a mouse model.These findings suggest that SARS-CoV-2 could hijack histones from neutrophil NETosis to promote its host cell attachment and entry process and may be important in exploring pathogenesis and possible strategies to develop new effective therapies for COVID-19.展开更多
基金National Key R&D Program of China,Grant/Award Number:2023YFC3402000National Institutes for Food and Drug Control,State Key Laboratory of Drug Regulatory Science,Grant/Award Number:2023SKLDRS0124。
文摘Background:The precise insertion of large DNA fragments(>3–5 kb)remains one of the key obstacles in establishment of genetically modified murine models.Methods:A 21 kb large DNA fragment containing three tandemly linked copies of the human HRAS gene was inserted into the genome of C57BL/6J mouse,generating a mouse model designated as KI.C57-ras(or named NF-h HRAS).Whole-genome sequencing and Sanger sequencing were utilized to it confirm precise insertion and copy number.The stability of transgene expression among different generations was verified from multiple aspects using by digital PCR,western blot and DNA sequencing.To assess tumor susceptibility in the mouse model,N-Nitroso-N-methylurea(MNU)was administered at a dosage of 75 mg/kg.Histopathological examinations were conducted using hematoxylin and eosin(H&E)staining.Results:The HRAS DNA fragment was inserted into mouse chromosome 15E1 site,locating between 80623202 bp and 80625020 bp.NF-h HRAS mice exhibited stable inheritance and displayed consistent phenotypes across individuals.Moreover,this mouse model exhibited a high susceptibility to carcinogens.Upon administration of MNU the earliest mortality onset was earlier than that of wild-type littermates(day 65 vs.day 78 for male and day 56 vs.day 84 for female).Notably,100%of the NF-h HRAS transgenic mice developed tumors,with approximately 84%of male NF-h HRAS mice exhibiting specific tumor types,such as squamous cell carcinoma or squamous cell papilloma,which was consistent with the previously reported carcinogenic rasH2 mouse model.The types of tumors and the target organs exhibited diversity in NFh HRAS mice,while the spontaneous tumor incidence remained low(1/50).Conclusions:The NF-h HRAS mice demonstrated excellent genetic stability,a reproducible phenotype,and high susceptibility to carcinogens,indicating their potential utility in non-clinical safety evaluations of drugs as per the S1B guidelines issued by the ICH(The International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use).
基金supported by the National Key Research and Development Project of China(2020YFC0842200,2020YFA0707801,and 2021YFC0863300)the National Natural Science Foundation of China(No.82041044)+2 种基金supported by the National Science Fund for Distinguished Young Scholars(81925025)the Innovative Research Group(81621005)from the NSFCthe Innovation Fund for Medical Sciences(2019-I2M-5-049)from the Chinese Academy of Medical Sciences。
文摘Dear Editor,Since the outbreak of COVID-19 at the end of 2019,its causative agent SARS-Co V-2 has been spreading around the world for one and half a year.During the long global circulation of SARS-Co V-2,mutations in the viral genome gradually emerged and accumulated。
基金We are grateful for the support by the National Key R&D Program of China(2021YFC2301700)National Science and Technology Major Projects of Infectious Disease funds(2017ZX103304402)。
文摘COVID-19,caused by SARS-CoV-2,is the most consequential pandemic of this century.Since the outbreak in late 2019,animal models have been playing crucial roles in aiding the rapid development of vaccines/drugs for prevention and therapy,as well as understanding the pathogenesis of SARS-CoV-2 infection and immune responses of hosts.However,the current animal models have some deficits and there is an urgent need for novel models to evaluate the virulence of variants of concerns(VOC),antibodydependent enhancement(ADE),and various comorbidities of COVID-19.This review summarizes the clinical features of COVID-19 in different populations,and the characteristics of the major animal models of SARS-CoV-2,including those naturally susceptible animals,such as non-human primates,Syrian hamster,ferret,minks,poultry,livestock,and mouse models sensitized by genetically modified,AAV/adenoviral transduced,mouse-adapted strain of SARS-CoV-2,and by engraftment of human tissues or cells.Since understanding the host receptors and proteases is essential for designing advanced genetically modified animal models,successful studies on receptors and proteases are also reviewed.Several improved alternatives for future mouse models are proposed,including the reselection of alternative receptor genes or multiple gene combinations,the use of transgenic or knock-in method,and different strains for establishing the next generation of genetically modified mice.
基金supported by the National Key Research and Development Program of China(No.2016YFA0201402)National Natural Science Foundation Regional Innovation and Development(U19A2003)the National Major Scientific and Technological Special Project for"Significant New Drugs Development"(No.2018ZX09733001).
文摘Dear Editor,The COVID-19 pandemic has covered more than 200 countries and regions around the world since its outbreak in January 2020.To date,the SARS-CoV-2 virus has caused>1.2 million deaths.The mortality rate of COVID-19 is closely concerned with the clinical symptoms of the patients from mild-to-severe disease.Notably,in its most severe form,COVID-19 leads to life-threatening pneumonia and acute respiratory distress syndrome(ARDS),which is mostly accom-panied by a hyperactive immune response called"cytokine storm"and has high death rates from 40 to 50%.
基金supported by the National Science Foundation for Excellent Young Scholars (32122052)National Natural Science Foundation Regional Innovation and Development (No.U19A2003).
文摘Neutrophil extracellular traps(NETs)can capture and kill viruses,such as influenza viruses,human immunodeficiency virus(HIV),and respiratory syncytial virus(RSV),thus contributing to host defense.Contrary to our expectation,we show here that the histones released by NETosis enhance the infectivity of SARS-CoV-2,as found by using live SARS-CoV-2 and two pseudovirus systems as well as a mouse model.The histone H3 or H4 selectively binds to subunit 2 of the spike(S)protein,as shown by a biochemical binding assay,surface plasmon resonance and binding energy calculation as well as the construction of a mutant S protein by replacing four acidic amino acids.Sialic acid on the host cell surface is the key molecule to which histones bridge subunit 2 of the S protein.Moreover,histones enhance cell-cell fusion.Finally,treatment with an inhibitor of NETosis,histone H3 or H4,or sialic acid notably affected the levels of sgRNA copies and the number of apoptotic cells in a mouse model.These findings suggest that SARS-CoV-2 could hijack histones from neutrophil NETosis to promote its host cell attachment and entry process and may be important in exploring pathogenesis and possible strategies to develop new effective therapies for COVID-19.
