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1.
J Virol ; 95(13): e0019221, 2021 06 10.
Article in English | MEDLINE | ID: covidwho-1486499

ABSTRACT

Understanding factors that affect the infectivity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is central to combatting coronavirus disease 2019 (COVID-19). The virus surface spike protein of SARS-CoV-2 mediates viral entry into cells by binding to the ACE2 receptor on epithelial cells and promoting fusion. We found that Epstein-Barr virus (EBV) induces ACE2 expression when it enters the lytic replicative cycle in epithelial cells. By using vesicular stomatitis virus (VSV) particles pseudotyped with the SARS-CoV-2 spike protein, we showed that lytic EBV replication enhances ACE2-dependent SARS-CoV-2 pseudovirus entry. We found that the ACE2 promoter contains response elements for Zta, an EBV transcriptional activator that is essential for EBV entry into the lytic cycle of replication. Zta preferentially acts on methylated promoters, allowing it to reactivate epigenetically silenced EBV promoters from latency. By using promoter assays, we showed that Zta directly activates methylated ACE2 promoters. Infection of normal oral keratinocytes with EBV leads to lytic replication in some of the infected cells, induces ACE2 expression, and enhances SARS-CoV-2 pseudovirus entry. These data suggest that subclinical EBV replication and lytic gene expression in epithelial cells, which is ubiquitous in the human population, may enhance the efficiency and extent of SARS-CoV-2 infection of epithelial cells by transcriptionally activating ACE2 and increasing its cell surface expression. IMPORTANCE SARS-CoV-2, the coronavirus responsible for COVID-19, has caused a pandemic leading to millions of infections and deaths worldwide. Identifying the factors governing susceptibility to SARS-CoV-2 is important in order to develop strategies to prevent SARS-CoV-2 infection. We show that Epstein-Barr virus, which infects and persists in >90% of adult humans, increases susceptibility of epithelial cells to infection by SARS-CoV-2. EBV, when it reactivates from latency or infects epithelial cells, increases expression of ACE2, the cellular receptor for SARS-CoV-2, enhancing infection by SARS-CoV-2. Inhibiting EBV replication with antivirals may therefore decrease susceptibility to SARS-CoV-2 infection.


Subject(s)
Angiotensin-Converting Enzyme 2/genetics , Epithelial Cells/virology , Herpesvirus 4, Human/physiology , SARS-CoV-2/physiology , Virus Internalization , Virus Replication , Angiotensin-Converting Enzyme 2/metabolism , Cell Line , DNA Methylation , Epithelial Cells/metabolism , Gene Expression Regulation , Humans , Promoter Regions, Genetic , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Trans-Activators/metabolism , Virus Activation
2.
Int J Mol Sci ; 22(3)2021 Jan 22.
Article in English | MEDLINE | ID: covidwho-1389387

ABSTRACT

In this review, we discuss the major histocompatibility complex (MHC) class II transactivator (CIITA), which is the master regulator of MHC class II gene expression. CIITA is the founding member of the mammalian nucleotide-binding and leucine-rich-repeat (NLR) protein family but stood apart for a long time as the only transcriptional regulator. More recently, it was found that its closest homolog, NLRC5 (NLR protein caspase activation and recruitment domain (CARD)-containing 5), is a regulator of MHC-I gene expression. Both act as non-DNA-binding activators through multiple protein-protein interactions with an MHC enhanceosome complex that binds cooperatively to a highly conserved combinatorial cis-acting module. Thus, the regulation of MHC-II expression is regulated largely through the differential expression of CIITA. In addition to the well-defined role of CIITA in MHC-II GENE regulation, we will discuss several other aspects of CIITA functions, such as its role in cancer, its role as a viral restriction element contributing to intrinsic immunity, and lastly, its very recently discovered role as an inhibitor of Ebola and SARS-Cov-2 virus replication. We will briefly touch upon the recently discovered role of NLRP3 as a transcriptional regulator, which suggests that transcriptional regulation is, after all, not such an unusual feature for NLR proteins.


Subject(s)
Genes, MHC Class II , NLR Proteins/metabolism , Nuclear Proteins/metabolism , Trans-Activators/metabolism , Animals , COVID-19/genetics , COVID-19/metabolism , Ebolavirus/physiology , Gene Expression Regulation , Hemorrhagic Fever, Ebola/genetics , Hemorrhagic Fever, Ebola/metabolism , Humans , NLR Proteins/genetics , Neoplasms/genetics , Neoplasms/metabolism , Nuclear Proteins/genetics , Protein Interaction Maps , SARS-CoV-2/physiology , Trans-Activators/genetics , Virus Replication
3.
Int J Mol Sci ; 22(3)2021 Jan 22.
Article in English | MEDLINE | ID: covidwho-1045412

ABSTRACT

In this review, we discuss the major histocompatibility complex (MHC) class II transactivator (CIITA), which is the master regulator of MHC class II gene expression. CIITA is the founding member of the mammalian nucleotide-binding and leucine-rich-repeat (NLR) protein family but stood apart for a long time as the only transcriptional regulator. More recently, it was found that its closest homolog, NLRC5 (NLR protein caspase activation and recruitment domain (CARD)-containing 5), is a regulator of MHC-I gene expression. Both act as non-DNA-binding activators through multiple protein-protein interactions with an MHC enhanceosome complex that binds cooperatively to a highly conserved combinatorial cis-acting module. Thus, the regulation of MHC-II expression is regulated largely through the differential expression of CIITA. In addition to the well-defined role of CIITA in MHC-II GENE regulation, we will discuss several other aspects of CIITA functions, such as its role in cancer, its role as a viral restriction element contributing to intrinsic immunity, and lastly, its very recently discovered role as an inhibitor of Ebola and SARS-Cov-2 virus replication. We will briefly touch upon the recently discovered role of NLRP3 as a transcriptional regulator, which suggests that transcriptional regulation is, after all, not such an unusual feature for NLR proteins.


Subject(s)
Genes, MHC Class II , NLR Proteins/metabolism , Nuclear Proteins/metabolism , Trans-Activators/metabolism , Animals , COVID-19/genetics , COVID-19/metabolism , Ebolavirus/physiology , Gene Expression Regulation , Hemorrhagic Fever, Ebola/genetics , Hemorrhagic Fever, Ebola/metabolism , Humans , NLR Proteins/genetics , Neoplasms/genetics , Neoplasms/metabolism , Nuclear Proteins/genetics , Protein Interaction Maps , SARS-CoV-2/physiology , Trans-Activators/genetics , Virus Replication
4.
Nat Commun ; 11(1): 4906, 2020 09 30.
Article in English | MEDLINE | ID: covidwho-807811

ABSTRACT

The CRISPR-Cas12a RNA-guided complexes have tremendous potential for nucleic acid detection but are limited to the picomolar detection limit without an amplification step. Here, we develop a platform with engineered crRNAs and optimized conditions that enabled us to detect various clinically relevant nucleic acid targets with higher sensitivity, achieving a limit of detection in the femtomolar range without any target pre-amplification step. By extending the 3'- or 5'-ends of the crRNA with different lengths of ssDNA, ssRNA, and phosphorothioate ssDNA, we discover a self-catalytic behavior and an augmented rate of LbCas12a-mediated collateral cleavage activity as high as 3.5-fold compared to the wild-type crRNA and with significant improvement in specificity for target recognition. Particularly, the 7-mer DNA extension to crRNA is determined to be universal and spacer-independent for enhancing the sensitivity and specificity of LbCas12a-mediated nucleic acid detection. We perform a detailed characterization of our engineered ENHANCE system with various crRNA modifications, target types, reporters, and divalent cations. With isothermal amplification of SARS-CoV-2 RNA using RT-LAMP, the modified crRNAs are incorporated in a paper-based lateral flow assay that can detect the target with up to 23-fold higher sensitivity within 40-60 min.


Subject(s)
Bacterial Proteins/metabolism , Betacoronavirus/genetics , CRISPR-Associated Proteins/metabolism , Endodeoxyribonucleases/metabolism , Nucleic Acid Amplification Techniques/methods , RNA, Viral/isolation & purification , Trans-Activators/metabolism , Betacoronavirus/isolation & purification , COVID-19 , COVID-19 Testing , CRISPR-Cas Systems , Clinical Laboratory Techniques , Clustered Regularly Interspaced Short Palindromic Repeats , Coronavirus Infections/diagnosis , Coronavirus Infections/virology , DNA, Single-Stranded , Pandemics , Pneumonia, Viral , RNA, Guide/genetics , RNA, Viral/genetics , SARS-CoV-2
5.
ACS Nano ; 14(10): 13964-13974, 2020 10 27.
Article in English | MEDLINE | ID: covidwho-766008

ABSTRACT

RNA quantification methods are broadly used in life science research and in clinical diagnostics. Currently, real-time reverse transcription polymerase chain reaction (RT-qPCR) is the most common analytical tool for RNA quantification. However, in cases of rare transcripts or inhibiting contaminants in the sample, an extensive amplification could bias the copy number estimation, leading to quantification errors and false diagnosis. Single-molecule techniques may bypass amplification but commonly rely on fluorescence detection and probe hybridization, which introduces noise and limits multiplexing. Here, we introduce reverse transcription quantitative nanopore sensing (RT-qNP), an RNA quantification method that involves synthesis and single-molecule detection of gene-specific cDNAs without the need for purification or amplification. RT-qNP allows us to accurately quantify the relative expression of metastasis-associated genes MACC1 and S100A4 in nonmetastasizing and metastasizing human cell lines, even at levels for which RT-qPCR quantification produces uncertain results. We further demonstrate the versatility of the method by adapting it to quantify severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA against a human reference gene. This internal reference circumvents the need for producing a calibration curve for each measurement, an imminent requirement in RT-qPCR experiments. In summary, we describe a general method to process complicated biological samples with minimal losses, adequate for direct nanopore sensing. Thus, harnessing the sensitivity of label-free single-molecule counting, RT-qNP can potentially detect minute expression levels of RNA biomarkers or viral infection in the early stages of disease and provide accurate amplification-free quantification.


Subject(s)
Biosensing Techniques/methods , Nanopores , RNA, Messenger/analysis , Single Molecule Imaging/methods , Betacoronavirus/genetics , Biosensing Techniques/standards , HCT116 Cells , Humans , RNA, Messenger/genetics , RNA, Messenger/metabolism , RNA, Viral/genetics , RNA, Viral/metabolism , S100 Calcium-Binding Protein A4/genetics , S100 Calcium-Binding Protein A4/metabolism , SARS-CoV-2 , Single Molecule Imaging/standards , Trans-Activators/genetics , Trans-Activators/metabolism
6.
J Virol ; 94(15)2020 07 16.
Article in English | MEDLINE | ID: covidwho-382053

ABSTRACT

Porcine deltacoronavirus (PDCoV) is an emerging swine enteropathogenic coronavirus. The nonstructural protein nsp5, also called 3C-like protease, is responsible for processing viral polyprotein precursors in coronavirus (CoV) replication. Previous studies have shown that PDCoV nsp5 cleaves the NF-κB essential modulator and the signal transducer and activator of transcription 2 to disrupt interferon (IFN) production and signaling, respectively. Whether PDCoV nsp5 also cleaves IFN-stimulated genes (ISGs), IFN-induced antiviral effector molecules, remains unclear. In this study, we screened 14 classical ISGs and found that PDCoV nsp5 cleaved the porcine mRNA-decapping enzyme 1a (pDCP1A) through its protease activity. Similar cleavage of endogenous pDCP1A was also observed in PDCoV-infected cells. PDCoV nsp5 cleaved pDCP1A at glutamine 343 (Q343), and the cleaved pDCP1A fragments, pDCP1A1-343 and pDCP1A344-580, were unable to inhibit PDCoV infection. Mutant pDCP1A-Q343A, which resists nsp5-mediated cleavage, exhibited a stronger ability to inhibit PDCoV infection than wild-type pDCP1A. Interestingly, the Q343 cleavage site is highly conserved in DCP1A homologs from other mammalian species. Further analyses demonstrated that nsp5 encoded by seven tested CoVs that can infect human or pig also cleaved pDCP1A and human DCP1A, suggesting that DCP1A may be the common target for cleavage by nsp5 of mammalian CoVs.IMPORTANCE Interferon (IFN)-stimulated gene (ISG) induction through IFN signaling is important to create an antiviral state and usually directly inhibits virus infection. The present study first demonstrated that PDCoV nsp5 can cleave mRNA-decapping enzyme 1a (DCP1A) to attenuate its antiviral activity. Furthermore, cleaving DCP1A is a common characteristic of nsp5 proteins from different coronaviruses (CoVs), which represents a common immune evasion mechanism of CoVs. Previous evidence showed that CoV nsp5 cleaves the NF-κB essential modulator and signal transducer and activator of transcription 2. Taken together, CoV nsp5 is a potent IFN antagonist because it can simultaneously target different aspects of the host IFN system, including IFN production and signaling and effector molecules.


Subject(s)
Antiviral Agents/pharmacology , Coronavirus/drug effects , Coronavirus/metabolism , Cysteine Endopeptidases/metabolism , Endoribonucleases/metabolism , Trans-Activators/metabolism , Viral Nonstructural Proteins/metabolism , Animals , Coronavirus 3C Proteases , Coronavirus Infections/veterinary , Coronavirus Infections/virology , Cysteine Endopeptidases/chemistry , Exoribonucleases/metabolism , HEK293 Cells , Host-Pathogen Interactions , Humans , Immune Evasion , Interferons/metabolism , STAT2 Transcription Factor/metabolism , Signal Transduction , Swine , Swine Diseases/virology
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