1
|
Sinha P, Thio CL, Balagopal A. Intracellular Host Restriction of Hepatitis B Virus Replication. Viruses 2024; 16:764. [PMID: 38793645 PMCID: PMC11125714 DOI: 10.3390/v16050764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Revised: 05/06/2024] [Accepted: 05/08/2024] [Indexed: 05/26/2024] Open
Abstract
The hepatitis B virus (HBV) infects hepatocytes and hijacks host cellular mechanisms for its replication. Host proteins can be frontline effectors of the cell's defense and restrict viral replication by impeding multiple steps during its intracellular lifecycle. This review summarizes many of the well-described restriction factors, their mechanisms of restriction, and counteractive measures of HBV, with a special focus on viral transcription. We discuss some of the limitations and knowledge gaps about the restriction factors, highlighting how these factors may be harnessed to facilitate therapeutic strategies against HBV.
Collapse
Affiliation(s)
| | | | - Ashwin Balagopal
- Department of Medicine, Division of Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; (P.S.); (C.L.T.)
| |
Collapse
|
2
|
Chang M, Min YQ, Xu Z, Deng F, Wang H, Ning YJ. Host factor MxA restricts Dabie bandavirus infection by targeting the viral NP protein to inhibit NP-RdRp interaction and ribonucleoprotein activity. J Virol 2024; 98:e0156823. [PMID: 38054738 PMCID: PMC10805036 DOI: 10.1128/jvi.01568-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Accepted: 11/20/2023] [Indexed: 12/07/2023] Open
Abstract
Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease with high case mortality rates, which is caused by Dabie bandavirus (DBV), a novel pathogen also termed as SFTS virus (SFTSV). Currently, no specific therapeutic drugs or vaccines are available for SFTS. Myxovirus resistance protein A (MxA) has been shown to inhibit multiple viral pathogens; however, the role of MxA in DBV infection is unknown. Here, we demonstrated that DBV stimulates MxA expression which, in turn, restricts DBV infection. Mechanistic target analysis revealed that MxA specifically interacts with the viral nucleocapsid protein (NP) in a manner independent of RNA. Minigenome reporter assay showed that in agreement with its targeting of NP, MxA inhibits DBV ribonucleoprotein (RNP) activity. In detail, MxA interacts with the NP N-terminal and disrupts the interaction of NP with the viral RNA-dependent RNA polymerase (RdRp) but not NP multimerization, the critical activities of NP for RNP formation and function. Furthermore, MxA N-terminal domain was identified as the functional domain inhibiting DBV infection, and, consistently, then was shown to interact with NP and obstruct the NP-RdRp interaction. Additionally, threonine 103 within the N-terminal domain is important for MxA inhibition to DBV, and its mutation (T103A) attenuates MxA binding to NP and obstruction of the NP-RdRp interaction. This study uncovers MxA inhibition of DBV with a series of functional and mechanistical analyses, providing insights into the virus-host interactions and probably helping inform the development of antiviral agents in the future.IMPORTANCEDBV/SFTSV is an emerging high-pathogenic virus. Since its first identification in China in 2009, cases of DBV infection have been reported in many other countries, posing a significant threat to public health. Uncovering the mechanisms of DBV-host interactions is necessary to understand the viral pathogenesis and host response and may advance the development of antiviral therapeutics. Here, we found that host factor MxA whose expression is induced by DBV restricts the virus infection. Mechanistically, MxA specifically interacts with the viral NP and blocks the NP-RdRp interaction, inhibiting the viral RNP activity. Further studies identified the key domain and amino acid residue required for MxA inhibition to DBV. Consistently, they were then shown to be important for MxA targeting of NP and obstruction of the NP-RdRp association. These findings unravel the restrictive role of MxA in DBV infection and the underlying mechanism, expanding our knowledge of the virus-host interactions.
Collapse
Affiliation(s)
- Meng Chang
- Key Laboratory of Virology and Biosafety and National Virus Resource Center, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yuan-Qin Min
- Key Laboratory of Virology and Biosafety and National Virus Resource Center, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
- State Key Laboratory of Virology and Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, China
| | - Zhao Xu
- Key Laboratory of Virology and Biosafety and National Virus Resource Center, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Fei Deng
- Key Laboratory of Virology and Biosafety and National Virus Resource Center, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
- State Key Laboratory of Virology and Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, China
| | - Hualin Wang
- Key Laboratory of Virology and Biosafety and National Virus Resource Center, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
- State Key Laboratory of Virology and Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, China
| | - Yun-Jia Ning
- Key Laboratory of Virology and Biosafety and National Virus Resource Center, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
- State Key Laboratory of Virology and Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, China
- Hubei Jiangxia Laboratory, Wuhan, China
| |
Collapse
|
3
|
Wu HH, Li YJ, Weng CH, Hsu HH, Chang MY, Yang HY, Yang CW, Tian YC. Interferon-alpha and MxA inhibit BK polyomavirus replication by interaction with polyomavirus large T antigen. Biomed J 2023; 47:100682. [PMID: 38065365 DOI: 10.1016/j.bj.2023.100682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 11/11/2023] [Accepted: 12/02/2023] [Indexed: 08/30/2024] Open
Abstract
INTRODUCTION BK Polyomavirus (BKPyV) infection is a common complication in kidney transplant recipients and can result in poor outcomes and graft failure. Currently, there is no known effective antiviral agent. This study investigated the possible antiviral effects of Interferon alpha (IFNα) and its induced protein, MxA, against BKPyV. METHODS In vitro cell culture experiments were conducted using human primary renal proximal tubular epithelial cells (HRPTECs). We also did animal studies using Balb/c mice with unilateral kidney ischemic reperfusion injury. RESULTS Our results demonstrated that IFNα effectively inhibited BKPyV in vitro and murine polyomavirus in animal models. Additionally, IFNα and MxA were found to suppress BKPyV TAg and VP1 production. Silencing MxA attenuated the antiviral efficacy of IFNα. We observed that MxA interacted with BKPyV TAg, causing it to remain in the cytosol and preventing its nuclear translocation. To determine MxA's essential domain for its antiviral activities, different mutant MxA constructs were generated. The MxA mutant K83A retained its interaction with BKPyV TAg, and its antiviral effects were intact. The MxA T103A mutant, on the other hand, abolished GTPase activity, lost its protein-protein interaction with BKPyV TAg, and lost its antiviral effect. CONCLUSION IFNα and its downstream protein, MxA, have potent antiviral properties against BKPyV. Furthermore, our findings indicate that the interaction between MxA and BKVPyV TAg plays a crucial role in determining the anti-BKPyV effects of MxA.
Collapse
Affiliation(s)
- Hsin-Hsu Wu
- Kidney Research Center, Department of Nephrology, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan; Department of Medicine, Chang Gung University, Taoyuan, Taiwan; Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Taiwan
| | - Yi-Jung Li
- Kidney Research Center, Department of Nephrology, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan; Department of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Cheng-Hao Weng
- Kidney Research Center, Department of Nephrology, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan; Department of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Hsiang-Hao Hsu
- Kidney Research Center, Department of Nephrology, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan; Department of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Ming-Yang Chang
- Kidney Research Center, Department of Nephrology, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan; Department of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Huang-Yu Yang
- Kidney Research Center, Department of Nephrology, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan; Department of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Chih-Wei Yang
- Kidney Research Center, Department of Nephrology, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan; Department of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Ya-Chung Tian
- Kidney Research Center, Department of Nephrology, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan; Department of Medicine, Chang Gung University, Taoyuan, Taiwan.
| |
Collapse
|
4
|
Escudero-Pérez B, Lalande A, Mathieu C, Lawrence P. Host–Pathogen Interactions Influencing Zoonotic Spillover Potential and Transmission in Humans. Viruses 2023; 15:v15030599. [PMID: 36992308 PMCID: PMC10060007 DOI: 10.3390/v15030599] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 02/13/2023] [Accepted: 02/20/2023] [Indexed: 02/24/2023] Open
Abstract
Emerging infectious diseases of zoonotic origin are an ever-increasing public health risk and economic burden. The factors that determine if and when an animal virus is able to spill over into the human population with sufficient success to achieve ongoing transmission in humans are complex and dynamic. We are currently unable to fully predict which pathogens may appear in humans, where and with what impact. In this review, we highlight current knowledge of the key host–pathogen interactions known to influence zoonotic spillover potential and transmission in humans, with a particular focus on two important human viruses of zoonotic origin, the Nipah virus and the Ebola virus. Namely, key factors determining spillover potential include cellular and tissue tropism, as well as the virulence and pathogenic characteristics of the pathogen and the capacity of the pathogen to adapt and evolve within a novel host environment. We also detail our emerging understanding of the importance of steric hindrance of host cell factors by viral proteins using a “flytrap”-type mechanism of protein amyloidogenesis that could be crucial in developing future antiviral therapies against emerging pathogens. Finally, we discuss strategies to prepare for and to reduce the frequency of zoonotic spillover occurrences in order to minimize the risk of new outbreaks.
Collapse
Affiliation(s)
- Beatriz Escudero-Pérez
- WHO Collaborating Centre for Arbovirus and Haemorrhagic Fever Reference and Research, Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany
- German Center for Infection Research (DZIF), Partner Site Hamburg-Luebeck-Borstel-Reims, 38124 Braunschweig, Germany
| | - Alexandre Lalande
- CIRI (Centre International de Recherche en Infectiologie), Team Neuro-Invasion, TROpism and VIRal Encephalitis, INSERM U1111, CNRS UMR5308, Université Claude Bernard Lyon 1, Ecole Normale Supérieure de Lyon, 69007 Lyon, France
| | - Cyrille Mathieu
- CIRI (Centre International de Recherche en Infectiologie), Team Neuro-Invasion, TROpism and VIRal Encephalitis, INSERM U1111, CNRS UMR5308, Université Claude Bernard Lyon 1, Ecole Normale Supérieure de Lyon, 69007 Lyon, France
| | - Philip Lawrence
- CONFLUENCE: Sciences et Humanités (EA 1598), Université Catholique de Lyon (UCLy), 69002 Lyon, France
- Correspondence:
| |
Collapse
|
5
|
McKellar J, Arnaud-Arnould M, Chaloin L, Tauziet M, Arpin-André C, Pourcelot O, Blaise M, Moncorgé O, Goujon C. An evolutionarily conserved N-terminal leucine is essential for MX1 GTPase antiviral activity against different families of RNA viruses. J Biol Chem 2023; 299:102747. [PMID: 36436557 PMCID: PMC9808005 DOI: 10.1016/j.jbc.2022.102747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 11/14/2022] [Accepted: 11/16/2022] [Indexed: 11/27/2022] Open
Abstract
Myxovirus resistance protein 1 (MX1) and MX2 are homologous, dynamin-like large GTPases, induced upon interferon exposure. Human MX1 (HsMX1) is known to inhibit many viruses, including influenza A virus, by likely acting at various steps of their life cycles. Despite decades of studies, the mechanism(s) of action with which MX1 proteins manage to inhibit target viruses is not fully understood. MX1 proteins are mechano-enzymes and share a similar organization to dynamin, with a GTPase domain and a carboxy-terminal stalk domain, connected by a bundle signaling element. These three elements are known to be essential for antiviral activity. HsMX1 has two unstructured regions, the L4 loop, also essential for antiviral activity, and a short amino (N)-terminal region, which greatly varies between MX1 proteins of different species. The role of this N-terminal domain in antiviral activity is not known. Herein, using mutagenesis, imaging, and biochemical approaches, we demonstrate that the N-terminal domain of HsMX1 is essential for antiviral activity against influenza A virus, Vesicular Stomatitis Virus, and La Crosse virus. Furthermore, we pinpoint a highly conserved leucine within this region, which is absolutely crucial for human, mouse, and bat MX1 protein antiviral activity. Importantly, mutation of this leucine does not compromise GTPase activity or oligomerization capabilities but does modify MX1 protein subcellular localization. The discovery of this essential and highly conserved residue defines this region as key for antiviral activity and may reveal insights as to the mechanism(s) of action of MX1 proteins.
Collapse
Affiliation(s)
- Joe McKellar
- IRIM, CNRS, Montpellier University, Montpellier, France
| | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Comparative Proteomic Analysis Reveals Mx1 Inhibits Senecavirus A Replication in PK-15 Cells by Interacting with the Capsid Proteins VP1, VP2 and VP3. Viruses 2022; 14:v14050863. [PMID: 35632606 PMCID: PMC9147370 DOI: 10.3390/v14050863] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Revised: 04/13/2022] [Accepted: 04/20/2022] [Indexed: 01/27/2023] Open
Abstract
As an emergent picornavirus pathogenic to pigs, Senecavirus A (SVA) can replicate in pig kidneys and proliferates well in porcine kidney epithelial PK-15 cells. Here, tandem mass tags (TMT) labeling coupled with liquid chromatography–tandem mass spectrometry (LC-MS/MS) was used to analyze the proteome dynamic changes in PK-15 cells during SVA infection. In total, 314, 697 and 426 upregulated differentially expressed proteins (DEPs) and 131, 263 and 342 downregulated DEPs were identified at 12, 24 and 36 hpi, respectively. After ensuring reliability of the proteomic data by quantitative PCR and Western blot testing of five randomly selected DEPs, Mx1, eIF4E, G6PD, TOP1 and PGAM1, all the DEPs were subjected to multiple bioinformatics analyses, including GO, COG, KEGG and STRING. The results reveal that the DEPs were mainly involved in host innate and adaptive immune responses in the early and middle stages of SVA infection, while the DEPs mainly participated in various metabolic processes in the late stage of infection. Finally, we demonstrated that Mx1 protein exerts antiviral activity against SVA by interacting with VP1 and VP2 proteins dependent on its GTPase, oligomerization and interaction activities, while Mx1 interacts with VP3 only depending on its oligomerization activity. Collectively, our study provides valuable clues for further investigation of SVA pathogenesis.
Collapse
|
7
|
Host Cell Restriction Factors of Paramyxoviruses and Pneumoviruses. Viruses 2020; 12:v12121381. [PMID: 33276587 PMCID: PMC7761617 DOI: 10.3390/v12121381] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 11/30/2020] [Accepted: 11/30/2020] [Indexed: 01/04/2023] Open
Abstract
The paramyxo- and pneumovirus family includes a wide range of viruses that can cause respiratory and/or systemic infections in humans and animals. The significant disease burden of these viruses is further exacerbated by the limited therapeutics that are currently available. Host cellular proteins that can antagonize or limit virus replication are therefore a promising area of research to identify candidate molecules with the potential for host-targeted therapies. Host proteins known as host cell restriction factors are constitutively expressed and/or induced in response to virus infection and include proteins from interferon-stimulated genes (ISGs). Many ISG proteins have been identified but relatively few have been characterized in detail and most studies have focused on studying their antiviral activities against particular viruses, such as influenza A viruses and human immunodeficiency virus (HIV)-1. This review summarizes current literature regarding host cell restriction factors against paramyxo- and pneumoviruses, on which there is more limited data. Alongside discussion of known restriction factors, this review also considers viral countermeasures in overcoming host restriction, the strengths and limitations in different experimental approaches in studies reported to date, and the challenges in reconciling differences between in vitro and in vivo data. Furthermore, this review provides an outlook regarding the landscape of emerging technologies and tools available to study host cell restriction factors, as well as the suitability of these proteins as targets for broad-spectrum antiviral therapeutics.
Collapse
|
8
|
Subcellular Localization of MxB Determines Its Antiviral Potential against Influenza A Virus. J Virol 2020; 94:JVI.00125-20. [PMID: 32907985 PMCID: PMC7592211 DOI: 10.1128/jvi.00125-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 09/01/2020] [Indexed: 11/20/2022] Open
Abstract
The interferon system plays a pivotal role in the defense against viral infections. The dynamin-related Mx proteins form a small family of interferon-induced effector proteins with distinct antiviral specificities and subcellular localizations. So far, it is not clear whether the different virus specificities of Mx proteins are the result of distinct mechanisms of action or are due rather to their different subcellular localization. We show here that the human MxB protein, normally localized to the outer membrane of the cell nucleus, acquires antiviral activity against IAV when redirected to the nucleus or cytoplasm, subcellular sites where other members of the Mx protein family efficiently interfere with IAV replication. Our findings thus strongly suggest that Mx proteins act primarily through a common mechanism and that their viral specificity is at least in part determined by their individual subcellular localization. Mx proteins are interferon (IFN) type I (α/β)- and type III (λ)-induced effector proteins with intrinsic antiviral activity. Mammalian Mx proteins show different subcellular localizations and distinct yet partially overlapping viral specificities. However, the precise mechanism(s) of antiviral action are still unresolved. Human MxA accumulates in the cytoplasm and inhibits a wide variety of RNA and DNA viruses, among them influenza A virus (IAV). In contrast, MxB, the second human Mx protein, localizes via its amino (N) terminus to the outer nuclear membrane at or near nuclear pores and inhibits the nuclear import of incoming human immunodeficiency viruses (HIV) and herpesviruses, but not that of IAV. Here, we evaluated whether the antiviral specificity of MxB is determined by its subcellular localization. For this purpose, we redirected MxB to the nucleus or cytoplasm by either attaching a nuclear localization signal to its N terminus or by exchanging the N terminus of MxB with that of MxA. Interestingly, ectopic expression of these MxB variants in the nucleus or in the cytoplasm rendered the host cells resistant to IAV, revealing that the capacity of MxB to block IAV replication critically depends on the site where the protein accumulates in the infected cell. Furthermore, coimmunoprecipitation (co-IP) assays demonstrated that MxB physically interacted with the nucleoprotein (NP) of IAV. Taken together, the data indicate that the subcellular localization of the MxB protein plays a pivotal role in determining its antiviral specificity. IMPORTANCE The interferon system plays a pivotal role in the defense against viral infections. The dynamin-related Mx proteins form a small family of interferon-induced effector proteins with distinct antiviral specificities and subcellular localizations. So far, it is not clear whether the different virus specificities of Mx proteins are the result of distinct mechanisms of action or are due rather to their different subcellular localization. We show here that the human MxB protein, normally localized to the outer membrane of the cell nucleus, acquires antiviral activity against IAV when redirected to the nucleus or cytoplasm, subcellular sites where other members of the Mx protein family efficiently interfere with IAV replication. Our findings thus strongly suggest that Mx proteins act primarily through a common mechanism and that their viral specificity is at least in part determined by their individual subcellular localization.
Collapse
|
9
|
A MicroRNA Network Controls Legionella pneumophila Replication in Human Macrophages via LGALS8 and MX1. mBio 2020; 11:mBio.03155-19. [PMID: 32209695 PMCID: PMC7157531 DOI: 10.1128/mbio.03155-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cases of Legionella pneumophila pneumonia occur worldwide, with potentially fatal outcome. When causing human disease, Legionella injects a plethora of virulence factors to reprogram macrophages to circumvent immune defense and create a replication niche. By analyzing Legionella-induced changes in miRNA expression and genomewide chromatin modifications in primary human macrophages, we identified a cell-autonomous immune network restricting Legionella growth. This network comprises three miRNAs governing expression of the cytosolic RNA receptor DDX58/RIG-I, the tumor suppressor TP53, the antibacterial effector LGALS8, and MX1, which has been described as an antiviral factor. Our findings for the first time link TP53, LGALS8, DDX58, and MX1 in one miRNA-regulated network and integrate them into a functional node in the defense against L. pneumophila. Legionella pneumophila is an important cause of pneumonia. It invades alveolar macrophages and manipulates the immune response by interfering with signaling pathways and gene transcription to support its own replication. MicroRNAs (miRNAs) are critical posttranscriptional regulators of gene expression and are involved in defense against bacterial infections. Several pathogens have been shown to exploit the host miRNA machinery to their advantage. We therefore hypothesize that macrophage miRNAs exert positive or negative control over Legionella intracellular replication. We found significant regulation of 85 miRNAs in human macrophages upon L. pneumophila infection. Chromatin immunoprecipitation and sequencing revealed concordant changes of histone acetylation at the putative promoters. Interestingly, a trio of miRNAs (miR-125b, miR-221, and miR-579) was found to significantly affect intracellular L. pneumophila replication in a cooperative manner. Using proteome-analysis, we pinpointed this effect to a concerted downregulation of galectin-8 (LGALS8), DExD/H-box helicase 58 (DDX58), tumor protein P53 (TP53), and then MX dynamin-like GTPase 1 (MX1) by the three miRNAs. In summary, our results demonstrate a new miRNA-controlled immune network restricting Legionella replication in human macrophages.
Collapse
|
10
|
Human MX2/MxB: a Potent Interferon-Induced Postentry Inhibitor of Herpesviruses and HIV-1. J Virol 2018; 92:JVI.00709-18. [PMID: 30258007 DOI: 10.1128/jvi.00709-18] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Interferons limit viral replication by inducing intracellular restriction factors, such as the GTPase MxB (also designated MX2), which inhibits HIV-1 and, as recently shown, herpesviruses. Inhibition of these viruses occurs at ill-defined steps after viral entry and requires formation of MxB dimers or oligomers, but GTP hydrolysis is needed only for blocking herpesviruses. Together with previous findings on related MxA, the new research on MxB highlights the mechanistic diversity by which MX proteins interfere with viral replication.
Collapse
|
11
|
Porcine Mx1 Protein Inhibits Classical Swine Fever Virus Replication by Targeting Nonstructural Protein NS5B. J Virol 2018; 92:JVI.02147-17. [PMID: 29343573 DOI: 10.1128/jvi.02147-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 01/09/2018] [Indexed: 12/16/2022] Open
Abstract
Mx proteins are interferon (IFN)-induced GTPases that have broad antiviral activity against a wide range of RNA and DNA viruses; they belong to the dynamin superfamily of large GTPases. In this study, we confirmed the anti-classical swine fever virus (CSFV) activity of porcine Mx1 in vitro and showed that porcine Mx2 (poMx2), human MxA (huMxA), and mouse Mx1 (mmMx1) also have anti-CSFV activity in vitro Small interfering RNA (siRNA) experiments revealed that depletion of endogenous poMx1 or poMx2 enhanced CSFV replication, suggesting that porcine Mx proteins are responsible for the antiviral activity of interferon alpha (IFN-α) against CSFV infection. Confocal microscopy, immunoprecipitation, glutathione S-transferase (GST) pulldown, and bimolecular fluorescence complementation (BiFC) demonstrated that poMx1 associated with NS5B, the RNA-dependent RNA polymerase (RdRp) of CSFV. We used mutations in the poMx1 protein to elucidate the mechanism of their anti-CSFV activity and found that mutants that disrupted the association with NS5B lost all anti-CSV activity. Moreover, an RdRp activity assay further revealed that poMx1 undermined the RdRp activities of NS5B. Together, these results indicate that porcine Mx proteins exert their antiviral activity against CSFV by interacting with NS5B.IMPORTANCE Our previous studies have shown that porcine Mx1 (poMx1) inhibits classical swine fever virus (CSFV) replication in vitro and in vivo, but the molecular mechanism of action remains largely unknown. In this study, we dissect the molecular mechanism of porcine Mx1 and Mx2 against CSFV in vitro Our results show that poMx1 associates with NS5B, the RNA-dependent RNA polymerase of CSFV, resulting in the reduction of CSFV replication. Moreover, the mutants of poMx1 further elucidate the mechanism of their anti-CSFV activities.
Collapse
|
12
|
Graf L, Dick A, Sendker F, Barth E, Marz M, Daumke O, Kochs G. Effects of allelic variations in the human myxovirus resistance protein A on its antiviral activity. J Biol Chem 2018; 293:3056-3072. [PMID: 29330299 DOI: 10.1074/jbc.m117.812784] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 01/08/2018] [Indexed: 11/06/2022] Open
Abstract
Only a minority of patients infected with seasonal influenza A viruses exhibit a severe or fatal outcome of infection, but the reasons for this inter-individual variability in influenza susceptibility are unclear. To gain further insights into the molecular mechanisms underlying this variability, we investigated naturally occurring allelic variations of the myxovirus resistance 1 (MX1) gene coding for the influenza restriction factor MxA. The interferon-induced dynamin-like GTPase consists of an N-terminal GTPase domain, a bundle signaling element, and a C-terminal stalk responsible for oligomerization and viral target recognition. We used online databases to search for variations in the MX1 gene. Deploying in vitro approaches, we found that non-synonymous variations in the GTPase domain cause the loss of antiviral and enzymatic activities. Furthermore, we showed that these amino acid substitutions disrupt the interface for GTPase domain dimerization required for the stimulation of GTP hydrolysis. Variations in the stalk were neutral or slightly enhanced or abolished MxA antiviral function. Remarkably, two other stalk variants altered MxA's antiviral specificity. Variations causing the loss of antiviral activity were found only in heterozygous carriers. Interestingly, the inactive stalk variants blocked the antiviral activity of WT MxA in a dominant-negative way, suggesting that heterozygotes are phenotypically MxA-negative. In contrast, the GTPase-deficient variants showed no dominant-negative effect, indicating that heterozygous carriers should remain unaffected. Our results demonstrate that naturally occurring mutations in the human MX1 gene can influence MxA function, which may explain individual variations in influenza virus susceptibility in the human population.
Collapse
Affiliation(s)
- Laura Graf
- From the Institute of Virology, Medical Center-University of Freiburg, Hermann-Herder-Strasse 11, 79104 Freiburg, Germany.,the Spemann Graduate School of Biology and Medicine, University of Freiburg, Albertstrasse 19a, 79104 Freiburg, Germany
| | - Alexej Dick
- the Max-Delbrück Centrum for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany.,the Institute of Chemistry and Biochemistry, Free University Berlin, Takustrasse 6, 14195 Berlin, Germany
| | - Franziska Sendker
- From the Institute of Virology, Medical Center-University of Freiburg, Hermann-Herder-Strasse 11, 79104 Freiburg, Germany
| | - Emanuel Barth
- the Bioinformatics/High Throughput Analysis, Friedrich Schiller University Jena, Leutragraben 1, 07743 Jena, Germany
| | - Manja Marz
- the Bioinformatics/High Throughput Analysis, Friedrich Schiller University Jena, Leutragraben 1, 07743 Jena, Germany.,the Leibniz Institute for Age Research-Fritz Lipmann Institute (FLI), Beutenbergstrasse 11, 07745 Jena, Germany.,the European Virus Bioinformatics Center, Leutragraben 1, 07743 Jena, Germany, and
| | - Oliver Daumke
- the Max-Delbrück Centrum for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany, .,the Institute of Chemistry and Biochemistry, Free University Berlin, Takustrasse 6, 14195 Berlin, Germany
| | - Georg Kochs
- From the Institute of Virology, Medical Center-University of Freiburg, Hermann-Herder-Strasse 11, 79104 Freiburg, Germany, .,the Spemann Graduate School of Biology and Medicine, University of Freiburg, Albertstrasse 19a, 79104 Freiburg, Germany.,the Faculty of Medicine, University of Freiburg, 79085 Freiburg, Germany
| |
Collapse
|
13
|
Ciancanelli MJ, Abel L, Zhang SY, Casanova JL. Host genetics of severe influenza: from mouse Mx1 to human IRF7. Curr Opin Immunol 2016; 38:109-20. [PMID: 26761402 PMCID: PMC4733643 DOI: 10.1016/j.coi.2015.12.002] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 11/30/2015] [Accepted: 12/03/2015] [Indexed: 12/22/2022]
Abstract
Influenza viruses cause mild to moderate respiratory illness in most people, and only rarely devastating or fatal infections. The virulence factors encoded by viral genes can explain seasonal or geographic differences at the population level but are unlikely to account for inter-individual clinical variability. Inherited or acquired immunodeficiencies may thus underlie severe cases of influenza. The crucial role of host genes was first demonstrated by forward genetics in inbred mice, with the identification of interferon (IFN)-α/β-inducible Mx1 as a canonical influenza susceptibility gene. Reverse genetics has subsequently characterized the in vivo role of other mouse genes involved in IFN-α/β and -λ immunity. A series of in vitro studies with mouse and human cells have also refined the cell-intrinsic mechanisms of protection against influenza viruses. Population-based human genetic studies have not yet uncovered variants with a significant impact. Interestingly, human primary immunodeficiencies affecting T and B cells were also not found to predispose to severe influenza. Recently however, human IRF7 was shown to be essential for IFN-α/β- and IFN-λ-dependent protective immunity against primary influenza in vivo, as inferred from a patient with life-threatening influenza revealed to be IRF7-deficient by whole exome sequencing. Next generation sequencing of human exomes and genomes will facilitate the analysis of the human genetic determinism of severe influenza.
Collapse
Affiliation(s)
- Michael J Ciancanelli
- St Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA.
| | - Laurent Abel
- St Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA; Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM-U1163, Necker Hospital for Sick Children, Paris, France; Paris Descartes University, Imagine Institute, Paris, France
| | - Shen-Ying Zhang
- St Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA; Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM-U1163, Necker Hospital for Sick Children, Paris, France; Paris Descartes University, Imagine Institute, Paris, France
| | - Jean-Laurent Casanova
- St Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA; Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM-U1163, Necker Hospital for Sick Children, Paris, France; Paris Descartes University, Imagine Institute, Paris, France; Howard Hughes Medical Institute, New York, NY, USA; Pediatric Hematology-Immunology Unit, Necker Hospital for Sick Children, Paris, France
| |
Collapse
|
14
|
Haller O, Staeheli P, Schwemmle M, Kochs G. Mx GTPases: dynamin-like antiviral machines of innate immunity. Trends Microbiol 2015; 23:154-63. [PMID: 25572883 DOI: 10.1016/j.tim.2014.12.003] [Citation(s) in RCA: 326] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 11/28/2014] [Accepted: 12/03/2014] [Indexed: 01/09/2023]
Abstract
The Mx dynamin-like GTPases are key antiviral effector proteins of the type I and type III interferon (IFN) systems. They inhibit several different viruses by blocking early steps of the viral replication cycle. We focus on new structural and functional insights and discuss recent data revealing that human MxA (MX1) provides a safeguard against introduction of avian influenza A viruses (FLUAV) into the human population. The related human MxB (MX2) serves as restriction factor for HIV-1 and other primate lentiviruses.
Collapse
Affiliation(s)
- Otto Haller
- Institute of Virology, University Medical Center Freiburg, Freiburg, Germany.
| | - Peter Staeheli
- Institute of Virology, University Medical Center Freiburg, Freiburg, Germany.
| | - Martin Schwemmle
- Institute of Virology, University Medical Center Freiburg, Freiburg, Germany
| | - Georg Kochs
- Institute of Virology, University Medical Center Freiburg, Freiburg, Germany
| |
Collapse
|
15
|
Mx proteins: antiviral gatekeepers that restrain the uninvited. Microbiol Mol Biol Rev 2014; 77:551-66. [PMID: 24296571 DOI: 10.1128/mmbr.00024-13] [Citation(s) in RCA: 219] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Fifty years after the discovery of the mouse Mx1 gene, researchers are still trying to understand the molecular details of the antiviral mechanisms mediated by Mx proteins. Mx proteins are evolutionarily conserved dynamin-like large GTPases, and GTPase activity is required for their antiviral activity. The expression of Mx genes is controlled by type I and type III interferons. A phylogenetic analysis revealed that Mx genes are present in almost all vertebrates, usually in one to three copies. Mx proteins are best known for inhibiting negative-stranded RNA viruses, but they also inhibit other virus families. Recent structural analyses provide hints about the antiviral mechanisms of Mx proteins, but it is not known how they can suppress such a wide variety of viruses lacking an obvious common molecular pattern. Perhaps they interact with a (partially) symmetrical invading oligomeric structure, such as a viral ribonucleoprotein complex. Such an interaction may be of a fairly low affinity, in line with the broad target specificity of Mx proteins, yet it would be strong enough to instigate Mx oligomerization and ring assembly. Such a model is compatible with the broad "substrate" specificity of Mx proteins: depending on the size of the invading viral ribonucleoprotein complexes that need to be wrapped, the assembly process would consume the necessary amount of Mx precursor molecules. These Mx ring structures might then act as energy-consuming wrenches to disassemble the viral target structure.
Collapse
|
16
|
Wang B, Zhao XP, Fan YC, Zhang JJ, Zhao J, Wang K. IL-17A but not IL-22 suppresses the replication of hepatitis B virus mediated by over-expression of MxA and OAS mRNA in the HepG2.2.15 cell line. Antiviral Res 2013; 97:285-92. [PMID: 23274784 DOI: 10.1016/j.antiviral.2012.12.018] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 12/14/2012] [Accepted: 12/17/2012] [Indexed: 02/08/2023]
Abstract
Interleukin-17A (IL-17A) and interleukin-22 (IL-22), mainly secreted by interleukin-17-producing T help cells (Th17), are pleiotropic cytokines that regulate the biological responses of several target cells, including hepatocytes. Th17 frequency was reported to negatively correlate with plasma hepatitis B virus (HBV) DNA load in patients with HBV infection. Several studies have indicated that cytokines, such as IL-6 and IL-4, are involved in the noncytopathic suppression of HBV replication. We therefore hypothesized that IL-17A and IL-22 might have a potent suppressive effect on HBV replication. In our present study, we analyzed the suppressive effect of IL-17A and IL-22 on HBV replication in the hepatocellular carcinoma cell line HepG2.2.15. IL-17A did not inhibit the proliferation of HepG2.2.15 cells. It decreased the levels of HBV s antigen (HBsAg) and HBV e antigen (HBeAg) in culture medium and the levels of intracellular HBV DNA. By contrast, blockage of IL-17 receptor (IL-17R) increased the levels of HBsAg and extracellular HBV DNA in culture medium and the levels of intracellular HBV DNA. The expression of antiviral proteins, including myxovirus resistance A (MxA) and oligoadenylate synthetase (OAS), was enhanced by IL-17A. IL-22 and anti-human IL-22 receptor (IL-22R) antibody did not change any indexes. We demonstrated that IL-17A effectively suppressed HBV replication in a noncytopathic manner and the over-expression of MxA and OAS mRNA was involved in the suppression of HBV replication by IL-17A.
Collapse
Affiliation(s)
- Bing Wang
- Department of Hepatology, Qilu Hospital of Shandong University, Wenhuaxi Road 107#, Jinan 250012, China
| | | | | | | | | | | |
Collapse
|
17
|
Pharmacogenomic update on multiple sclerosis: a focus on actual and new therapeutic strategies. THE PHARMACOGENOMICS JOURNAL 2012; 12:453-61. [PMID: 23044601 DOI: 10.1038/tpj.2012.41] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Multiple sclerosis (MS) is an inflammatory and demyelinating disease of central nervous system comprising several subtypes. Pharmacological treatment involves only few drugs. Among these, interferon beta (IFN-β) and glatiramer acetate were the most used. Although evidence supports the efficacy of these agents in treating MS symptoms, actual studies allowed to introduce new innovative drugs in clinical practice. Applying pharmacogenetic approach to MS, IFN-β and several other immune pathways were abundantly investigated. Numerous reports identified some promising therapy markers but only few markers have emerged as clinically useful. This may be partially due to differences in clinical and methodological criteria in the studies. Indeed, responder and non-responder definitions lack standardized clinical definition. The goal of this review is to treat advances in research on the pharmacogenetic markers of MS drugs and to highlight possible correlations between type of responses and genetic profile, with regard to clinical and methodological discrepancies in the studies.
Collapse
|
18
|
Cell-type specific interferon stimulated gene staining in liver underlies response to interferon therapy in chronic HBV infected patients. Dig Dis Sci 2012; 57:2355-61. [PMID: 22585383 DOI: 10.1007/s10620-012-2169-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 04/03/2012] [Indexed: 01/14/2023]
Abstract
BACKGROUND Interferon-α is approved as one of the main therapeutic treatments for chronic hepatitis B virus infection, but only a small number of patients achieve sustained virological response. The molecular mechanisms underlying IFN-α resistance in those patients who do not respond remain elusive. Previous work in our laboratory identified the pre-activation of IFN signaling leading to increased expression of a subset of interferon stimulated genes in the pretreatment liver tissues of chronic HBV infected patients correlated with treatment non-response. AIMS We studied the cell-type specific gene expression of interferon stimulated genes in the liver of chronic HBV infected patients and the cellular basis of the phenotype through ISG15 and MxA protein expression. METHODS Immunohistochemical analysis was used to detect the expression of ISG15 and MxA protein in the pretreatment liver tissues of chronic HBV infected patients and the expression patterns were correlated with treatment outcomes. RESULTS In the non-responders, ISG15 and MxA protein expression in the pretreatment liver tissues was more pronounced in hepatocytes while in the responders, ISG15 and MxA protein expression was more focused in macrophages. ISG15 and MxA proteins were occasionally expressed in hepatocytes in normal livers. CONCLUSION There were significant differences in the cell-type specific protein expression of ISG15 and MxA in the pretreatment liver tissues of chronic HBV infected patients between treatment responders and non-responders. An easy prediction method based on immunohistochemical stains of a subset of interferon stimulated genes may be developed to predict treatment outcomes of IFN therapy in chronic HBV infected patients.
Collapse
|
19
|
Li N, Zhang L, Chen L, Feng W, Xu Y, Chen F, Liu X, Chen Z, Liu W. MxA inhibits hepatitis B virus replication by interaction with hepatitis B core antigen. Hepatology 2012; 56:803-11. [PMID: 22271421 DOI: 10.1002/hep.25608] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 01/05/2012] [Indexed: 12/11/2022]
Abstract
UNLABELLED Human MxA, an interferon-inducible cytoplasmic dynamin-like GTPase, possesses antiviral activity against multiple RNA viruses. Recently, MxA has also been demonstrated to have activity against the hepatitis B virus (HBV), a well-known DNA virus responsible for acute and chronic liver disease in humans. We investigated the molecular mechanism for the anti-HBV activity of MxA. Our results demonstrated that in HepG2.2.15 cells, MxA GTPase independently suppressed the production of hepatitis B surface antigen and HBV DNA without changing the level of hepatitis B core antigen (HBcAg) and the distribution of HBV mRNA. MxA significantly reduced the level of the encapsidated pregenomic RNA. Through its central interactive domain, MxA interacted with HBcAg, causing accumulation of the proteins in perinuclear compartments. MxA-HBcAg interaction significantly affected the dynamics of HBcAg by immobilizing HBcAg in the perinuclear structures. CONCLUSION MxA displays antiviral activity against HBV involving a mechanism of MxA-HBcAg interaction that may interfere with core particle formation.
Collapse
Affiliation(s)
- Ning Li
- Department of Biochemistry and Molecular Biology, Program in Molecular Cell Biology, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Zhijian Y, Zhen H, Fan Z, Jin Y, Qiwen D, Zhongming Z. Hepatitis B virus core protein with hot-spot mutations inhibit MxA gene transcription but has no effect on inhibition of virus replication by interferon α. Virol J 2010; 7:278. [PMID: 20959021 PMCID: PMC2972278 DOI: 10.1186/1743-422x-7-278] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Accepted: 10/20/2010] [Indexed: 12/29/2022] Open
Abstract
It has been reported that hepatitis B virus (HBV) core protein (HBc) can inhibit the transcription of human interferon-induced MxA gene. In this study, we investigated whether HBc protein mutations at hot spots (L60V, S87G and I97L) could still inhibit MxA transcription and the potential significance of this inhibition in virus replication in vitro. Our data indicated that the IFN-induced MxA mRNA expression level and MxA promoter activity was significantly down-regulated by mutant protein of HBc(I97L), compared to WT and the other two mutated HBc proteins(L60V or S87G). However, in Huh7 cells stably expressing WT or the mutated HBc proteins (L60V, S87G or I97L), IFN-α could inhibit the extra- and intracellular HBV DNA level and HBsAg secretion to a similar level compared to that in cells transfected with control plasmids. In conclusion, HBc protein with I97L mutation may play an especial role in suppressing the transcription of MxA gene. Moreover, the inhibitory effect on MxA gene transcription by the WT or mutated HBc proteins (L60V, S87G and I97L) has no impact on inhibition of HBV replication by IFN-α in Huh7 cells. The clinical significance of the inhibitory effect of MxA gene transcription by HBc protein requires further study.
Collapse
Affiliation(s)
- Yu Zhijian
- Department of Infectious Diseases, the Affiliated Shenzhen Nanshan Hospital of Guangdong Medical College, Shenzhen, China
| | | | | | | | | | | |
Collapse
|
21
|
Liu HQ, Qin B. Advance in molecular mechanism of interferon to treat chronic hepatitis B. Shijie Huaren Xiaohua Zazhi 2009; 17:1803-1808. [DOI: 10.11569/wcjd.v17.i18.1803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The antiviral efficacy of interferon-α (IFN-α) therapy for chronic hepatitis B (CHB) is not only related to DNA load and genetype of HBV before treatment, gene mutation of HBV and polymorphism of type II HLA in the host, but also depends on the immunity of CHB patients. Researchers pay more and more attention to the mutant strain of virus and phenotypes of genes. However, the mechanism of interferon to resist HBV and the escape mechanism of HBV against the IFN therapy have not been clarified yet. This paper reviews the mechanism of IFN therapy and the influencing factors at molecular and genetic levels.
Collapse
|