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Huang X, Yin G, Zhou B, Cai Y, Hu J, Huang J, Chen Z, Liu Q, Feng X. KRT10 plays an important role in the release of viral genome from endosomes during H9N2 subtype AIV replication in HeLa cells. Vet Microbiol 2023; 284:109824. [PMID: 37406407 DOI: 10.1016/j.vetmic.2023.109824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 06/21/2023] [Accepted: 06/28/2023] [Indexed: 07/07/2023]
Abstract
The infection and replication of avian influenza virus (AIV) in host cells is a complex biological process that involves the transport of viral genes through the host cell's transport systems. Actin, microtubules and vimentin are known to facilitate transport of endosomes to the perinuclear region, but the biological role of Keratin, another intermediate filament, in viral transport during AIV replication is not well understood. In this study, the viral NS2 protein was used as the target protein to identify the potential interacting proteins following GST-Pulldown method and protein mass spectrometry. It was discovered that Keratin10 interacted with NS2. Subsequently, it was found AIV infection did not affect the gene level or protein level of keratin10 in HeLa cells, but when Keratin10 was knocked down, the expressions of viral NP mRNA and protein were reduced, and the generation of offspring virus also was also decreased. Furthermore, in early viral infection, Keratin10 could aggregate and co-localize with NP proteins, suggesting that Keratin10 might be connected to early viral transport. Additionally, it was demonstrated that Keratin10 co-localized with Lamp1 and that AIV particles were trapped in late endosomes/Lysosomes after Keratin10 was knocked down. Finally, it was discovered that the knocking down Keratin10 in HeLa cells led to an increase in the acidic pH of endosomes and lysosomes, which prevented AIV from undergoing fusion and uncoating, and then inhibited the process of the viral infection. Overall, the results suggested that Keratin10 might play the critical role in the release of vRNPs from LEs/Ls and can affect the generation of offspring virus. The study provides the novel insights into the role of Keratin10 in the process of AIV infection and transmission, which may have implications for developing new strategies to against AIV infections.
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Affiliation(s)
- Xiangyu Huang
- Key Laboratory of Animal Microbiology of China's Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Guihu Yin
- Key Laboratory of Animal Microbiology of China's Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Bin Zhou
- Key Laboratory of Animal Microbiology of China's Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Yiqin Cai
- Key Laboratory of Animal Microbiology of China's Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Jianing Hu
- Key Laboratory of Animal Microbiology of China's Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Jingwen Huang
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Zili Chen
- Agricultural Comprehensive Law Enforcement Brigade of Rudong, Rudong Agriculture and Rural Affairs Bureau, Rudong 226400, China
| | - Qingtao Liu
- Key Laboratory of Veterinary Biological Engineering and Technology, Ministry of Agriculture, Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Xiuli Feng
- Key Laboratory of Animal Microbiology of China's Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
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Zhong Y, Yan W, Ruan J, Fang M, Yu C, Du S, Rai G, Tao D, Henderson MJ, Fang S. XBP1 variant 1 promotes mitosis of cancer cells involving upregulation of the polyglutamylase TTLL6. Hum Mol Genet 2022; 31:2639-2654. [PMID: 35333353 PMCID: PMC9396943 DOI: 10.1093/hmg/ddac010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 12/19/2021] [Accepted: 01/10/2022] [Indexed: 11/15/2022] Open
Abstract
XBP1 variant 1 (Xv1) is the most abundant XBP1 variant and is highly enriched across cancer types but nearly none in normal tissues. Its expression is associated with poor patients' survival and is specifically required for survival of malignant cells, but the underlying mechanism is not known. Here we report that Xv1 upregulates the polyglutamylase tubulin tyrosine ligase-like 6 (TTLL6) and promotes mitosis of cancer cells. Like the canonical XBP1, Xv1 mRNA undergoes unconventional splicing by IRE1α under endoplasmic reticulum stress, but it is also constitutively spliced by IRE1β. The spliced Xv1 mRNA encodes the active form of Xv1 protein (Xv1s). RNA sequencing in HeLa cells revealed that Xv1s overexpression regulates expression of genes that are not involved in the canonical unfolded protein response, including TTLL6 as a highly upregulated gene. Gel shift assay and chromatin immunoprecipitation revealed that Xv1s bind to the TTLL6 promoter region. Knockdown of TTLL6 caused death of cancer cells but not benign and normal cells, similar to the effects of knocking down Xv1. Moreover, overexpression of TTLL6 partially rescued BT474 cells from apoptosis induced by either TTLL6 or Xv1 knockdown, supporting TTLL6 as an essential downstream effector of Xv1 in regulating cancer cell survival. TTLL6 is localized in the mitotic spindle of cancer cells. Xv1 or TTLL6 knockdown resulted in decreased spindle polyglutamylation and interpolar spindle, as well as congression failure, mitotic arrest and cell death. These findings suggest that Xv1 is essential for cancer cell mitosis, which is mediated, at least in part, by increasing TTLL6 expression.
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Affiliation(s)
- Yongwang Zhong
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Wenjing Yan
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Jingjing Ruan
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Pulmonary Medicine, Anhui Medical University First Affiliated Hospital, Hefei, Anhui 230032, China
| | - Mike Fang
- Population and Quantitative Health Sciences Department, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Changjun Yu
- Department of General surgery, Anhui Medical University First Affiliated Hospital, Hefei, Anhui 230032, China
| | - Shaojun Du
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Ganesha Rai
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD 20850, USA
| | - Dingyin Tao
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD 20850, USA
| | - Mark J Henderson
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD 20850, USA
| | - Shengyun Fang
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Program in Oncology, UM Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Iselin L, Palmalux N, Kamel W, Simmonds P, Mohammed S, Castello A. Uncovering viral RNA-host cell interactions on a proteome-wide scale. Trends Biochem Sci 2022; 47:23-38. [PMID: 34509361 PMCID: PMC9187521 DOI: 10.1016/j.tibs.2021.08.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 07/12/2021] [Accepted: 08/06/2021] [Indexed: 01/14/2023]
Abstract
RNA viruses interact with a wide range of cellular RNA-binding proteins (RBPs) during their life cycle. The prevalence of these host-virus interactions has been highlighted by new methods that elucidate the composition of viral ribonucleoproteins (vRNPs). Applied to 11 viruses so far, these approaches have revealed hundreds of cellular RBPs that interact with viral (v)RNA in infected cells. However, consistency across methods is limited, raising questions about methodological considerations when designing and interpreting these studies. Here, we discuss these caveats and, through comparing available vRNA interactomes, describe RBPs that are consistently identified as vRNP components and outline their potential roles in infection. In summary, these novel approaches have uncovered a new universe of host-virus interactions holding great therapeutic potential.
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Affiliation(s)
- Louisa Iselin
- Nuffield Department of Medicine, Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, OX1 3SY, UK; Department of Biochemistry, University of Oxford, South Parks Road, OX1 3QU, Oxford, UK
| | - Natasha Palmalux
- MRC-University of Glasgow Centre for Virus Research, 464 Bearsden Road, Glasgow G61 1QH, Scotland, (UK)
| | - Wael Kamel
- Department of Biochemistry, University of Oxford, South Parks Road, OX1 3QU, Oxford, UK; MRC-University of Glasgow Centre for Virus Research, 464 Bearsden Road, Glasgow G61 1QH, Scotland, (UK)
| | - Peter Simmonds
- Nuffield Department of Medicine, Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, OX1 3SY, UK
| | - Shabaz Mohammed
- Department of Biochemistry, University of Oxford, South Parks Road, OX1 3QU, Oxford, UK; Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK; The Rosalind Franklin Institute, Oxfordshire, OX11 0FA, UK
| | - Alfredo Castello
- Department of Biochemistry, University of Oxford, South Parks Road, OX1 3QU, Oxford, UK; MRC-University of Glasgow Centre for Virus Research, 464 Bearsden Road, Glasgow G61 1QH, Scotland, (UK).
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De Conto F, Conversano F, Razin SV, Belletti S, Arcangeletti MC, Chezzi C, Calderaro A. Host-cell dependent role of phosphorylated keratin 8 during influenza A/NWS/33 virus (H1N1) infection in mammalian cells. Virus Res 2021; 295:198333. [PMID: 33556415 DOI: 10.1016/j.virusres.2021.198333] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 01/20/2021] [Accepted: 02/02/2021] [Indexed: 01/22/2023]
Abstract
In this study, we investigated the involvement of keratin 8 during human influenza A/NWS/33 virus (H1N1) infection in semi-permissive rhesus monkey-kidney (LLC-MK2) and permissive human type II alveolar epithelial (A549) cells. In A549 cells, keratin 8 showed major expression and phosphorylation levels. Influenza A/NWS/33 virus was able to subvert keratin 8 structural organization at late stages of infection in both cell models, promoting keratin 8 phosphorylation in A549 cells at early phases of infection. Accordingly, partial colocalizations of the viral nucleoprotein with keratin 8 and its phosphorylated form were assessed by confocal microscopy at early stages of infection in A549 cells. The employment of chemical activators of phosphorylation resulted in structural changes as well as increased phosphorylation of keratin 8 in both cell models, favoring the influenza A/NWS/33 virus's replicative efficiency in A549 but not in LLC-MK2 cells. In A549 and human larynx epidermoid carcinoma (HEp-2) cells inoculated with respiratory secretions from pediatric patients positive for, respectively, influenza A virus or respiratory syncytial virus, the keratin 8 phosphorylation level had increased only in the case of influenza A virus infection. The results obtained suggest that in A549 cells the influenza virus is able to induce keratin 8 phosphorylation thereby enhancing its replicative efficiency.
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Affiliation(s)
- Flora De Conto
- Department of Medicine and Surgery, University of Parma, Parma, Italy.
| | | | - Sergey V Razin
- Institute of Gene Biology, Russian Academy of Sciences and Lomonosov Moscow State University, Moscow, Russia
| | - Silvana Belletti
- Department of Medicine and Surgery, University of Parma, Parma, Italy
| | | | - Carlo Chezzi
- Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Adriana Calderaro
- Department of Medicine and Surgery, University of Parma, Parma, Italy
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5
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Carnes SK, Aiken C. Host proteins involved in microtubule-dependent HIV-1 intracellular transport and uncoating. Future Virol 2019. [DOI: 10.2217/fvl-2019-0004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Microtubules and microtubule-associated proteins are critical for cargo transport throughout the cell. Many viruses are able to usurp these transport systems for their own replication and spread. HIV-1 utilizes these proteins for many of its early events postentry, including transport, uncoating and reverse transcription. The molecular motor proteins dynein and kinesin-1 are the primary drivers of cargo transport, and HIV-1 utilizes these proteins for infection. In this Review, we highlight recent developments in the understanding of how HIV-1 hijacks motor transport, the key cellular and viral proteins involved, and the ways that transport influences other steps in the HIV-1 lifecycle.
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Affiliation(s)
- Stephanie K Carnes
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN 37212, USA
| | - Christopher Aiken
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN 37212, USA
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Bedi S, Ono A. Friend or Foe: The Role of the Cytoskeleton in Influenza A Virus Assembly. Viruses 2019; 11:v11010046. [PMID: 30634554 PMCID: PMC6356976 DOI: 10.3390/v11010046] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 01/02/2019] [Accepted: 01/08/2019] [Indexed: 12/12/2022] Open
Abstract
Influenza A Virus (IAV) is a respiratory virus that causes seasonal outbreaks annually and pandemics occasionally. The main targets of the virus are epithelial cells in the respiratory tract. Like many other viruses, IAV employs the host cell’s machinery to enter cells, synthesize new genomes and viral proteins, and assemble new virus particles. The cytoskeletal system is a major cellular machinery, which IAV exploits for its entry to and exit from the cell. However, in some cases, the cytoskeleton has a negative impact on efficient IAV growth. In this review, we highlight the role of cytoskeletal elements in cellular processes that are utilized by IAV in the host cell. We further provide an in-depth summary of the current literature on the roles the cytoskeleton plays in regulating specific steps during the assembly of progeny IAV particles.
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Affiliation(s)
- Sukhmani Bedi
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Akira Ono
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI 48109, USA.
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Intracellular Colocalization of Influenza Viral RNA and Rab11A Is Dependent upon Microtubule Filaments. J Virol 2017; 91:JVI.01179-17. [PMID: 28724771 PMCID: PMC5599730 DOI: 10.1128/jvi.01179-17] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 07/13/2017] [Indexed: 12/31/2022] Open
Abstract
Influenza A virus (IAV) consists of eight viral RNA (vRNA) segments that are replicated in the host cell nucleus and transported to the plasma membrane for packaging into progeny virions. We have previously proposed a model where subcomplexes of vRNA are exported from the nucleus and assembled en route to the plasma membrane. However, the role of host cytoskeletal proteins in the cytoplasmic assembly of IAV vRNA segments remains unknown. Previous studies have suggested that IAV vRNA segments are transported via Rab11A-containing recycling endosomes (RE) and use both microtubules (MT) and actin. Rab11A RE transport primarily along MT; therefore, investigation of the role of MT in vRNA assembly is warranted. We explored the role of MT in vRNA assembly and replication by using multiple IAV strains in various cell types, including primary human airway epithelial cells. We observed that Rab11A localization was altered in the presence of MT-depolymerizing drugs, but growth of IAV in all of the cell types tested was unchanged. Fluorescent in situ hybridization was performed to determine the role of MT in the assembly of multiple vRNA segments. Unexpectedly, we found that vRNA-vRNA association in cytoplasmic foci was independent of MT. Given the disparity of localization between Rab11A and vRNA segments in the absence of intact MT filaments, we analyzed the three-dimensional spatial relationship between Rab11A and vRNA in the cytoplasm of infected cells. We found that Rab11A and vRNA colocalization is dependent upon dynamic MT filaments. Taken together, our data suggest that cytoplasmic transport of influenza vRNA may include a Rab11A RE-independent mechanism. IMPORTANCE IAV infections cause a large public health burden through seasonal epidemics and sporadic pandemics. Pandemic IAVs emerge through reassortment of vRNA in animal or human hosts. Elucidation of the mechanism of intracellular dynamics of IAV assembly is necessary to understand reassortment. Our results describing the role of MT in vRNA transport and assembly expand upon previous studies characterizing vRNA assembly. This study is the first to assess the role of MT in influenza virus replication in human bronchial airway epithelial cells. In addition, we present novel data on the role of MT in facilitating the association between distinct vRNA segments. Interestingly, our results suggest that progressive assembly of vRNA segments may be cell type dependent and that vRNA may be transported through the cytoplasm without Rab11A RE in the absence of intact MT. These results enhance our understanding of vRNA assembly and the role of cytoskeletal proteins in that process.
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De Conto F, Fazzi A, Razin SV, Arcangeletti MC, Medici MC, Belletti S, Chezzi C, Calderaro A. Mammalian Diaphanous-related formin-1 restricts early phases of influenza A/NWS/33 virus (H1N1) infection in LLC-MK2 cells by affecting cytoskeleton dynamics. Mol Cell Biochem 2017; 437:185-201. [PMID: 28744815 DOI: 10.1007/s11010-017-3107-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 07/01/2017] [Indexed: 12/15/2022]
Abstract
Viruses depend on cellular machinery to efficiently replicate. The host cytoskeleton is one of the first cellular systems hijacked by viruses in order to ensure their intracellular transport and promote the development of infection. Our previous results demonstrated that stable microfilaments and microtubules interfered with human influenza A/NWS/33 virus (H1N1) infection in semi-permissive LLC-MK2 cells. Although formins play a key role in cytoskeletal remodelling, few studies addressed a possible role of these proteins in development of viral infection. Here, we have demonstrated that mammalian Diaphanous-related formin-1 (mDia1) is involved in the control of cytoskeleton dynamics during human influenza A virus infection. First, by employing cytoskeleton-perturbing drugs, we evidenced a cross-talk occurring between microtubules and microfilaments that also has implications on the intracellular localization of mDia1. In influenza A/NWS/33 virus-infected LLC-MK2 cells, mDia1 showed a highly dynamic intracellular localization and partially co-localized with actin and tubulin. A depletion of mDia1 by RNA-mediated RNA interference was found to improve the outcome of influenza A/NWS/33 virus infection and to increase the dynamics of microfilament and microtubule networks in LLC-MK2 cells. Consistent with these findings, observations made in epithelial respiratory cells from paediatric patients with acute respiratory disease assessed that the expression of mDia1 is stimulated by influenza A virus but not by respiratory syncytial virus. Taken together, the obtained results suggest that mDia1 restricts the initiation of influenza A/NWS/33 virus infection in LLC-MK2 cells by counteracting cytoskeletal dynamics.
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Affiliation(s)
- Flora De Conto
- Department of Medicine and Surgery, University of Parma, Parma, Italy.
| | - Alessandra Fazzi
- Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Sergey V Razin
- Institute of Gene Biology, Russian Academy of Sciences and Lomonosow Moscow State University, Moscow, Russia
| | | | | | - Silvana Belletti
- Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Carlo Chezzi
- Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Adriana Calderaro
- Department of Medicine and Surgery, University of Parma, Parma, Italy
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Abstract
UNLABELLED In the extracellular environment, cell-free virions seek out naive host cells over long distances and between organisms. This is the primary mechanism of spread for most viruses. Here we provide evidence for an alternative pathway previously undescribed for orthomyxoviruses, whereby the spread of influenza A virus (IAV) infectious cores to neighboring cells can occur within intercellular connections. The formation of these connections requires actin dynamics and is enhanced by viral infection. Connected cells have contiguous membranes, and the core infectious viral machinery (RNP and polymerase) was present inside the intercellular connections. A live-cell movie of green fluorescent protein (GFP)-tagged NS1 of IAV shows viral protein moving from one cell to another through an intercellular connection. The movement of tagged protein was saltatory but overall traveled only in one direction. Infectious virus cores can move from one cell to another without budding and release of cell-free virions, as evidenced by the finding that whereas a neuraminidase inhibitor alone did not inhibit the development of IAV microplaques, the presence of a neuraminidase inhibitor together with drugs inhibiting actin dynamics or the microtubule stabilizer paclitaxel (originally named taxol) precluded microplaque formation. Similar results were also observed with parainfluenza virus 5 (PIV5), a paramyxovirus, when neutralizing antibody was used to block spread by cell-free virions. Intercellular spread of infectious core particles was unaffected or enhanced in the presence of nocodazole for IAV but inhibited for PIV5. The intercellular connections have a core of filamentous actin, which hints toward transport of virus particles through the use of a myosin motor. IMPORTANCE Here we describe a new method by which influenza A virus (IAV) spreads from cell to cell: IAV uses intracellular connections. The formation of these connections requires actin dynamics and is enhanced by viral infection and the absence of microtubules. Connected cells appeared to have contiguous membranes, and the core infectious viral machinery (RNP and polymerase) was present inside the intercellular connections. Infectious virus cores can move from one cell to another without budding and release of cell-free virions. Similar results were also observed with parainfluenza virus 5 (PIV5).
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Edinger TO, Pohl MO, Stertz S. Entry of influenza A virus: host factors and antiviral targets. J Gen Virol 2013; 95:263-277. [PMID: 24225499 DOI: 10.1099/vir.0.059477-0] [Citation(s) in RCA: 159] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Influenza virus is a major human pathogen that causes annual epidemics and occasional pandemics. Moreover, the virus causes outbreaks in poultry and other animals, such as pigs, requiring costly and laborious countermeasures. Therefore, influenza virus has a substantial impact on health and the global economy. Here, we review entry of this important pathogen into target cells, an essential process by which viral genomes are delivered from extracellular virions to sites of transcription/replication in the cell nucleus. We summarize current knowledge on the interaction of influenza viruses with their receptor, sialic acid, and highlight the ongoing search for additional receptors. We describe receptor-mediated endocytosis and the recently discovered macropinocytosis as alternative virus uptake pathways, and illustrate the subsequent endosomal trafficking of the virus with advanced live microscopy techniques. Release of virus from the endosome and import of the viral ribonucleoproteins into the host cell nucleus are also outlined. Although a focus has been on viral protein function during entry, recent studies have revealed exciting information on cellular factors required for influenza virus entry. We highlight these, and discuss established entry inhibitors targeting viral and host factors, as well as the latest prospects for designing novel 'anti-entry' compounds. New entry inhibitors are of particular importance for current efforts to develop the next generation of anti-influenza drugs - entry is the first essential step of virus replication and is an ideal target to block infection efficiently.
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Affiliation(s)
- Thomas O Edinger
- Institute of Medical Virology, University of Zurich, 8057 Zurich, Switzerland
| | - Marie O Pohl
- Institute of Medical Virology, University of Zurich, 8057 Zurich, Switzerland
| | - Silke Stertz
- Institute of Medical Virology, University of Zurich, 8057 Zurich, Switzerland
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