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Zarek CM, Dende C, Coronado J, Pendse M, Dryden P, Hooper LV, Reese TA. Preexisting helminth challenge exacerbates infection and reactivation of gammaherpesvirus in tissue resident macrophages. PLoS Pathog 2023; 19:e1011691. [PMID: 37847677 PMCID: PMC10581490 DOI: 10.1371/journal.ppat.1011691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 09/17/2023] [Indexed: 10/19/2023] Open
Abstract
Even though gammaherpesvirus and parasitic infections are endemic in parts of the world, there is a lack of understanding about the outcome of coinfection. In humans, coinfections usually occur sequentially, with fluctuating order and timing in different hosts. However, experimental studies in mice generally do not address the variables of order and timing of coinfections. We sought to examine the variable of coinfection order in a system of gammaherpesvirus-helminth coinfection. Our previous work demonstrated that infection with the intestinal parasite, Heligmosomoides polygyrus, induced transient reactivation from latency of murine gammaherpesvirus-68 (MHV68). In this report, we reverse the order of coinfection, infecting with H. polygyrus first, followed by MHV68, and examined the effects of preexisting parasite infection on MHV68 acute and latent infection. We found that preexisting parasite infection increased the propensity of MHV68 to reactivate from latency. However, when we examined the mechanism for reactivation, we found that preexisting parasite infection increased the ability of MHV68 to reactivate in a vitamin A dependent manner, a distinct mechanism to what we found previously with parasite-induced reactivation after latency establishment. We determined that H. polygyrus infection increased both acute and latent MHV68 infection in a population of tissue resident macrophages, called large peritoneal macrophages. We demonstrate that this population of macrophages and vitamin A are required for increased acute and latent infection during parasite coinfection.
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Affiliation(s)
- Christina M. Zarek
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Chaitanya Dende
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Jaime Coronado
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Mihir Pendse
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Phillip Dryden
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Lora V. Hooper
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- The Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Tiffany A. Reese
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
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2
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Condrat CE, Cretoiu D, Radoi VE, Mihele DM, Tovaru M, Bordea CI, Voinea SC, Suciu N. Unraveling Immunological Dynamics: HPV Infection in Women-Insights from Pregnancy. Viruses 2023; 15:2011. [PMID: 37896788 PMCID: PMC10611104 DOI: 10.3390/v15102011] [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: 08/19/2023] [Revised: 09/23/2023] [Accepted: 09/26/2023] [Indexed: 10/29/2023] Open
Abstract
During pregnancy, hormonal and immune adaptations are vital for supporting the genetically distinct fetus during elevated infection risks. The global prevalence of HPV necessitates its consideration during pregnancy. Despite a seemingly mild immune response, historical gestational viral infections underscore its significance. Acknowledging the established HPV infection risks during pregnancy, our review explores the unfolding immunological changes in pregnant women with HPV. Our analysis aims to uncover strategies for safely modulating the immune system, mitigating adverse pregnancy consequences, and enhancing maternal and child health. This comprehensive narrative review delves into the existing knowledge and studies on this topic.
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Affiliation(s)
- Carmen Elena Condrat
- Department of Obstetrics and Gynecology, Polizu Clinical Hospital, Carol Davila University of Medicine and Pharmacy, 8 Eroii Sanitari Blvd., 050474 Bucharest, Romania; (C.E.C.)
| | - Dragos Cretoiu
- Department of Genetics, Carol Davila University of Medicine and Pharmacy, 8 Eroii Sanitari Blvd., 050474 Bucharest, Romania; (D.C.); (V.E.R.)
- Fetal Medicine Excellence Research Center, Alessandrescu-Rusescu National Institute for Mother and Child Health, 020395 Bucharest, Romania
| | - Viorica Elena Radoi
- Department of Genetics, Carol Davila University of Medicine and Pharmacy, 8 Eroii Sanitari Blvd., 050474 Bucharest, Romania; (D.C.); (V.E.R.)
- Fetal Medicine Excellence Research Center, Alessandrescu-Rusescu National Institute for Mother and Child Health, 020395 Bucharest, Romania
| | - Dana Mihaela Mihele
- Department of Dermatology, Carol Davila University of Medicine and Pharmacy, 8 Eroii Sanitari Blvd., 050474 Bucharest, Romania
- Dermatology Department, Victor Babes Clinical Hospital of Infectious and Tropical Diseases, 030303 Bucharest, Romania
| | - Mihaela Tovaru
- Department of Dermatology, Carol Davila University of Medicine and Pharmacy, 8 Eroii Sanitari Blvd., 050474 Bucharest, Romania
- Dermatology Department, Victor Babes Clinical Hospital of Infectious and Tropical Diseases, 030303 Bucharest, Romania
| | - Cristian Ioan Bordea
- Department of Surgical Oncology, Prof. Dr. Alexandru Trestioreanu Oncology Institute, Carol Davila University of Medicine and Pharmacy, 252 Fundeni Rd., 022328 Bucharest, Romania
| | - Silviu Cristian Voinea
- Department of Surgical Oncology, Prof. Dr. Alexandru Trestioreanu Oncology Institute, Carol Davila University of Medicine and Pharmacy, 252 Fundeni Rd., 022328 Bucharest, Romania
| | - Nicolae Suciu
- Department of Obstetrics and Gynecology, Polizu Clinical Hospital, Carol Davila University of Medicine and Pharmacy, 8 Eroii Sanitari Blvd., 050474 Bucharest, Romania; (C.E.C.)
- Fetal Medicine Excellence Research Center, Alessandrescu-Rusescu National Institute for Mother and Child Health, 020395 Bucharest, Romania
- Department of Obstetrics and Gynecology, Polizu Clinical Hospital, Alessandrescu-Rusescu National Institute for Mother and Child Health, 020395 Bucharest, Romania
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3
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Gaucherand L, Iyer A, Gilabert I, Rycroft CH, Gaglia MM. Cut site preference allows influenza A virus PA-X to discriminate between host and viral mRNAs. Nat Microbiol 2023; 8:1304-1317. [PMID: 37349586 PMCID: PMC10690756 DOI: 10.1038/s41564-023-01409-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 05/10/2023] [Indexed: 06/24/2023]
Abstract
Many viruses block host gene expression to take over the infected cell. This process, termed host shutoff, is thought to promote viral replication by preventing antiviral responses and redirecting cellular resources to viral processes. Several viruses from divergent families accomplish host shutoff through RNA degradation by endoribonucleases. However, viruses also need to ensure expression of their own genes. The influenza A virus endoribonuclease PA-X solves this problem by sparing viral mRNAs and some host RNAs necessary for viral replication. To understand how PA-X distinguishes between RNAs, we characterized PA-X cut sites transcriptome-wide using 5' rapid amplification of complementary DNA ends coupled to high-throughput sequencing. This analysis, along with RNA structure predictions and validation experiments using reporters, shows that PA-Xs from multiple influenza strains preferentially cleave RNAs at GCUG tetramers in hairpin loops. Importantly, GCUG tetramers are enriched in the human but not the influenza transcriptome. Moreover, optimal PA-X cut sites inserted in the influenza A virus genome are quickly selected against during viral replication in cells. This finding suggests that PA-X evolved these cleavage characteristics to preferentially target host over viral mRNAs in a manner reminiscent of cellular self versus non-self discrimination.
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Affiliation(s)
- Lea Gaucherand
- Program in Molecular Microbiology, Tufts University Graduate School of Biomedical Sciences, Boston, MA, USA
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
- Architecture et Réactivité de l'ARN, Institut de Biologie Moléculaire et Cellulaire du CNRS, Université de Strasbourg, Strasbourg, France
| | - Amrita Iyer
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
| | - Isabel Gilabert
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
- Faculty of Experimental Sciences, Universidad Francisco de Vitoria, Madrid, Spain
| | - Chris H Rycroft
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Mathematics, University of Wisconsin-Madison, Madison, WI, USA
| | - Marta M Gaglia
- Program in Molecular Microbiology, Tufts University Graduate School of Biomedical Sciences, Boston, MA, USA.
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA.
- Institute for Molecular Virology and Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, USA.
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4
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Gaunt ER, Digard P. Compositional biases in RNA viruses: Causes, consequences and applications. WILEY INTERDISCIPLINARY REVIEWS. RNA 2022; 13:e1679. [PMID: 34155814 PMCID: PMC8420353 DOI: 10.1002/wrna.1679] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 05/29/2021] [Accepted: 05/31/2021] [Indexed: 01/05/2023]
Abstract
If each of the four nucleotides were represented equally in the genomes of viruses and the hosts they infect, each base would occur at a frequency of 25%. However, this is not observed in nature. Similarly, the order of nucleotides is not random (e.g., in the human genome, guanine follows cytosine at a frequency of ~0.0125, or a quarter the number of times predicted by random representation). Codon usage and codon order are also nonrandom. Furthermore, nucleotide and codon biases vary between species. Such biases have various drivers, including cellular proteins that recognize specific patterns in nucleic acids, that once triggered, induce mutations or invoke intrinsic or innate immune responses. In this review we examine the types of compositional biases identified in viral genomes and current understanding of the evolutionary mechanisms underpinning these trends. Finally, we consider the potential for large scale synonymous recoding strategies to engineer RNA virus vaccines, including those with pandemic potential, such as influenza A virus and Severe Acute Respiratory Syndrome Coronavirus Virus 2. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Evolution and Genomics > Computational Analyses of RNA RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition.
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Affiliation(s)
- Eleanor R. Gaunt
- Department of Infection and ImmunityThe Roslin Institute, The University of EdinburghEdinburghUK
| | - Paul Digard
- Department of Infection and ImmunityThe Roslin Institute, The University of EdinburghEdinburghUK
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5
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Gaglia MM. Anti-viral and pro-inflammatory functions of Toll-like receptors during gamma-herpesvirus infections. Virol J 2021; 18:218. [PMID: 34749760 PMCID: PMC8576898 DOI: 10.1186/s12985-021-01678-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 10/12/2021] [Indexed: 12/15/2022] Open
Abstract
Toll-like receptors (TLRs) control anti-viral responses both directly in infected cells and in responding cells of the immune systems. Therefore, they are crucial for responses against the oncogenic γ-herpesviruses Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus and the related murine virus MHV68, which directly infect immune system cells. However, since these viruses also cause lifelong persistent infections, TLRs may also be involved in modulation of inflammation during latent infection and contribute to virus-driven tumorigenesis. This review summarizes work on both of these aspects of TLR/γ-herpesvirus interactions, as well as results showing that TLR activity can drive these viruses' re-entry into the replicative lytic cycle.
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Affiliation(s)
- Marta Maria Gaglia
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA.
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Jahanban‐Esfahlan R, Seidi K, Majidinia M, Karimian A, Yousefi B, Nabavi SM, Astani A, Berindan‐Neagoe I, Gulei D, Fallarino F, Gargaro M, Manni G, Pirro M, Xu S, Sadeghi M, Nabavi SF, Shirooie S. Toll‐like receptors as novel therapeutic targets for herpes simplex virus infection. Rev Med Virol 2019; 29:e2048. [DOI: 10.1002/rmv.2048] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 03/12/2019] [Accepted: 03/19/2019] [Indexed: 12/22/2022]
Affiliation(s)
- Rana Jahanban‐Esfahlan
- Department of Medical Biotechnology, Faculty of Advanced Medical SciencesTabriz University of Medical Sciences Tabriz Iran
- Drug Applied Research CenterTabriz University of Medical Sciences Tabriz Iran
| | - Khaled Seidi
- Immunology Research CenterTabriz University of Medical Sciences Tabriz Iran
| | - Maryam Majidinia
- Solid Tumor Research CenterUrmia University of Medical Sciences Urmia Iran
| | - Ansar Karimian
- Cellular and Molecular Biology Research Center, Health Research InstituteBabol University of Medical Sciences Babol Iran
| | - Bahman Yousefi
- Molecular Medicine Research CenterTabriz University of Medical Sciences Tabriz Iran
- Department of Biochemistry and Clinical Laboratories, Faculty of MedicineTabriz University of Medical Science Tabriz Iran
| | - Seyed Mohammad Nabavi
- Applied Biotechnology Research CenterBaqiyatallah University of Medical Sciences Tehran Iran
| | - Akram Astani
- Department of MicrobiologyShahid Sadoughi University of Medical Sciences Yazd Iran
| | - Ioana Berindan‐Neagoe
- MEDFUTURE ‐Research Center for Advanced Medicine“Iuliu‐Hatieganu” University of Medicine and Pharmacy Cluj‐Napoca Romania
- Research Centerfor Functional Genomics, Biomedicine and Translational Medicine“Iuliu‐Hatieganu” University of Medicine and Pharmacy Cluj‐Napoca Romania
- Department of Functional Genomics and Experimental PathologyThe Oncology Institute “Prof. Dr. Ion Chiricuţă” Cluj‐Napoca Romania
| | - Diana Gulei
- MEDFUTURE ‐Research Center for Advanced Medicine“Iuliu‐Hatieganu” University of Medicine and Pharmacy Cluj‐Napoca Romania
| | | | - Marco Gargaro
- Department of Experimental MedicineUniversity of Perugia Italy
| | - Giorgia Manni
- Department of Experimental MedicineUniversity of Perugia Italy
| | - Matteo Pirro
- Department of MedicineUniversity of Perugia Italy
| | - Suowen Xu
- Aab Cardiovascular Research InstituteUniversity of Rochester Rochester NY USA
| | - Mahmoud Sadeghi
- Department of Transplantation ImmunologyUniversity of Heidelberg Heidelberg Germany
| | - Seyed Fazel Nabavi
- Applied Biotechnology Research CenterBaqiyatallah University of Medical Sciences Tehran Iran
| | - Samira Shirooie
- Department of Pharmacology, Faculty of PharmacyKermanshah University of Medical Sciences Kermanshah Iran
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7
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Bussey KA, Murthy S, Reimer E, Chan B, Hatesuer B, Schughart K, Glaunsinger B, Adler H, Brinkmann MM. Endosomal Toll-Like Receptors 7 and 9 Cooperate in Detection of Murine Gammaherpesvirus 68 Infection. J Virol 2019; 93:e01173-18. [PMID: 30429335 PMCID: PMC6340039 DOI: 10.1128/jvi.01173-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 11/02/2018] [Indexed: 12/13/2022] Open
Abstract
Murine gammaherpesvirus 68 (MHV68) is a small-animal model suitable for study of the human pathogens Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus. Here, we have characterized the roles of the endosomal Toll-like receptor (TLR) escort protein UNC93B, endosomal TLR7, -9, and -13, and cell surface TLR2 in MHV68 detection. We found that the alpha interferon (IFN-α) response of plasmacytoid dendritic cells (pDC) to MHV68 was reduced in Tlr9-/- cells compared to levels in wild type (WT) cells but not completely lost. Tlr7-/- pDC responded similarly to WT. However, we found that in Unc93b-/- pDC, as well as in Tlr7-/-Tlr9-/- double-knockout pDC, the IFN-α response to MHV68 was completely abolished. Thus, the only pattern recognition receptors contributing to the IFN-α response to MHV68 in pDC are TLR7 and TLR9, but the contribution of TLR7 is masked by the presence of TLR9. To address the role of UNC93B and TLR for MHV68 infection in vivo, we infected mice with MHV68. Lytic replication of MHV68 after intravenous infection was enhanced in the lungs, spleen, and liver of UNC93B-deficient mice, in the spleen of TLR9-deficient mice, and in the liver and spleen of Tlr7-/-Tlr9-/- mice. The absence of TLR2 or TLR13 did not affect lytic viral titers. We then compared reactivation of MHV68 from latently infected WT, Unc93b-/-, Tlr7-/-Tlr9-/-, Tlr7-/-, and Tlr9-/- splenocytes. We observed enhanced reactivation and latent viral loads, particularly from Tlr7-/-Tlr9-/- splenocytes compared to levels in the WT. Our data show that UNC93B-dependent TLR7 and TLR9 cooperate in and contribute to detection and control of MHV68 infection.IMPORTANCE The two human gammaherpesviruses, Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV), can cause aggressive forms of cancer. These herpesviruses are strictly host specific, and therefore the homolog murine gammaherpesvirus 68 (MHV68) is a widely used model to obtain in vivo insights into the interaction between these two gammaherpesviruses and their host. Like EBV and KSHV, MHV68 establishes lifelong latency in B cells. The innate immune system serves as one of the first lines of host defense, with pattern recognition receptors such as the Toll-like receptors playing a crucial role in mounting a potent antiviral immune response to various pathogens. Here, we shed light on a yet unanticipated role of Toll-like receptor 7 in the recognition of MHV68 in a subset of immune cells called plasmacytoid dendritic cells, as well as on the control of this virus in its host.
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Affiliation(s)
- Kendra A Bussey
- Institute of Genetics, Technische Universität Braunschweig, Braunschweig, Germany
- Viral Immune Modulation Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Sripriya Murthy
- Viral Immune Modulation Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Elisa Reimer
- Viral Immune Modulation Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Baca Chan
- Viral Immune Modulation Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Bastian Hatesuer
- Department of Infection Genetics, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Klaus Schughart
- Department of Infection Genetics, Helmholtz Centre for Infection Research, Braunschweig, Germany
- University of Veterinary Medicine Hannover, Hannover, Germany
- Department of Microbiology, Immunology, and Biochemistry, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Britt Glaunsinger
- Department of Plant and Microbial Biology, University of California Berkeley, Howard Hughes Medical Institute, Berkeley, California, USA
| | - Heiko Adler
- Comprehensive Pneumology Center, Research Unit Lung Repair and Regeneration, Helmholtz Zentrum München-German Research Center for Environmental Health, German Center of Lung Research, Munich, Germany
| | - Melanie M Brinkmann
- Institute of Genetics, Technische Universität Braunschweig, Braunschweig, Germany
- Viral Immune Modulation Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
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8
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Alinejad-Rokny H, Anwar F, Waters SA, Davenport MP, Ebrahimi D. Source of CpG Depletion in the HIV-1 Genome. Mol Biol Evol 2016; 33:3205-3212. [PMID: 27682824 DOI: 10.1093/molbev/msw205] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The dinucleotide CpG is highly underrepresented in the genome of human immunodeficiency virus type 1 (HIV-1). To identify the source of CpG depletion in the HIV-1 genome, we investigated two biological mechanisms: (1) CpG methylation-induced transcriptional silencing and (2) CpG recognition by Toll-like receptors (TLRs). We hypothesized that HIV-1 has been under selective evolutionary pressure by these mechanisms leading to the reduction of CpG in its genome. A CpG depleted genome would enable HIV-1 to avoid methylation-induced transcriptional silencing and/or to avoid recognition by TLRs that identify foreign CpG sequences. We investigated these two hypotheses by determining the sequence context dependency of CpG depletion and comparing it with that of CpG methylation and TLR recognition. We found that in both human and HIV-1 genomes the CpG motifs flanked by T/A were depleted most and those flanked by C/G were depleted least. Similarly, our analyses of human methylome data revealed that the CpG motifs flanked by T/A were methylated most and those flanked by C/G were methylated least. Given that a similar CpG depletion pattern was observed for the human genome within which CpGs are not likely to be recognized by TLRs, we argue that the main source of CpG depletion in HIV-1 is likely host-induced methylation. Analyses of CpG motifs in over 100 viruses revealed that this unique CpG representation pattern is specific to the human and simian immunodeficiency viruses.
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Affiliation(s)
- Hamid Alinejad-Rokny
- Infection Analytics, Kirby Institute, UNSW Australia, Sydney, Australia.,Systems Biology and Genomics Lab, Harry Perkins Institute of Medical Research, The University of Western Australia, WA, Australia
| | - Firoz Anwar
- Infection Analytics, Kirby Institute, UNSW Australia, Sydney, Australia
| | - Shafagh A Waters
- School of Biotechnology and Biomolecular Sciences, Faculty of Science, UNSW Australia, Sydney, Australia
| | - Miles P Davenport
- Infection Analytics, Kirby Institute, UNSW Australia, Sydney, Australia
| | - Diako Ebrahimi
- Infection Analytics, Kirby Institute, UNSW Australia, Sydney, Australia .,Department of Biochemistry, Molecular Biology and Biophysics; Masonic Cancer Center; Institute for Molecular Virology, University of Minnesota, MN
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9
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Crow MS, Lum KK, Sheng X, Song B, Cristea IM. Diverse mechanisms evolved by DNA viruses to inhibit early host defenses. Crit Rev Biochem Mol Biol 2016; 51:452-481. [PMID: 27650455 PMCID: PMC5285405 DOI: 10.1080/10409238.2016.1226250] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In mammalian cells, early defenses against infection by pathogens are mounted through a complex network of signaling pathways shepherded by immune-modulatory pattern-recognition receptors. As obligate parasites, the survival of viruses is dependent on the evolutionary acquisition of mechanisms that tactfully dismantle and subvert the cellular intrinsic and innate immune responses. Here, we review the diverse mechanisms by which viruses that accommodate DNA genomes are able to circumvent activation of cellular immunity. We start by discussing viral manipulation of host defense protein levels by either transcriptional regulation or protein degradation. We next review viral strategies used to repurpose or inhibit these cellular immune factors by molecular hijacking or by regulating their post-translational modification status. Additionally, we explore the infection-induced temporal modulation of apoptosis to facilitate viral replication and spread. Lastly, the co-evolution of viruses with their hosts is highlighted by the acquisition of elegant mechanisms for suppressing host defenses via viral mimicry of host factors. In closing, we present a perspective on how characterizing these viral evasion tactics both broadens the understanding of virus-host interactions and reveals essential functions of the immune system at the molecular level. This knowledge is critical in understanding the sources of viral pathogenesis, as well as for the design of antiviral therapeutics and autoimmunity treatments.
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Affiliation(s)
- Marni S. Crow
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544
| | - Krystal K. Lum
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544
| | - Xinlei Sheng
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544
| | - Bokai Song
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544
| | - Ileana M. Cristea
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544
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10
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Karijolich J, Abernathy E, Glaunsinger BA. Infection-Induced Retrotransposon-Derived Noncoding RNAs Enhance Herpesviral Gene Expression via the NF-κB Pathway. PLoS Pathog 2015; 11:e1005260. [PMID: 26584434 PMCID: PMC4652899 DOI: 10.1371/journal.ppat.1005260] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 10/13/2015] [Indexed: 02/07/2023] Open
Abstract
Short interspersed nuclear elements (SINEs) are highly abundant, RNA polymerase III-transcribed noncoding retrotransposons that are silenced in somatic cells but activated during certain stresses including viral infection. How these induced SINE RNAs impact the host-pathogen interaction is unknown. Here we reveal that during murine gammaherpesvirus 68 (MHV68) infection, rapidly induced SINE RNAs activate the antiviral NF-κB signaling pathway through both mitochondrial antiviral-signaling protein (MAVS)-dependent and independent mechanisms. However, SINE RNA-based signaling is hijacked by the virus to enhance viral gene expression and replication. B2 RNA expression stimulates IKKβ-dependent phosphorylation of the major viral lytic cycle transactivator protein RTA, thereby enhancing its activity and increasing progeny virion production. Collectively, these findings suggest that SINE RNAs participate in the innate pathogen response mechanism, but that herpesviruses have evolved to co-opt retrotransposon activation for viral benefit. Short interspersed nuclear elements (SINEs) are noncoding mobile genetic elements that are present at ~106 copies per mammalian genome, roughly comprising 10% of mammalian genomic real estate. SINEs are typically transcriptionally silenced, though in some cases viral infection can promote their expression, yet to an unknown functional outcome. Thus, SINE elements represent the largest class of infection-inducible noncoding RNAs that are functionally uncharacterized. Here, we reveal that SINE RNAs play a critical role in the host-pathogen interaction in that they are required for efficient murine gammaherpesvirus 68 (MHV68) replication and gene expression. We demonstrate that SINE RNAs, both exogenously expressed and infection-induced, are robust activators of the IKKβ kinase, a key signaling molecule in the innate immune response. Activation of the IKKβ kinase by SINE RNA is mediated through both MAVS-dependent and independent mechanisms. Moreover, we demonstrate the activation of the IKKβ via SINE RNA is required to drive the phosphorylation of MHV68 RTA, the main viral transcriptional activator, which enhances its transcriptional activating property. Collectively, we reveal the first example of a role for SINE RNAs in the host-pathogen interaction and identify them as a key immune signaling molecule early during infection. Though SINE RNAs activate the innate immune response, MHV68 has co-opted SINE-mediate innate immune activation to enhance the viral lifecycle.
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Affiliation(s)
- John Karijolich
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, United States of America
| | - Emma Abernathy
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, United States of America
| | - Britt A. Glaunsinger
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, United States of America
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, United States of America
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, California, United States of America
- * E-mail:
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11
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Abstract
Many viruses deliver their genomes into the host cell’s nucleus before they replicate. While onco-retroviruses and papillomaviruses tether their genomes to host chromatin upon mitotic breakdown of the nuclear envelope, lentiviruses, such as human immunodeficiency virus, adenoviruses, herpesviruses, parvoviruses, influenza viruses, hepatitis B virus, polyomaviruses, and baculoviruses deliver their genomes into the nucleus of post-mitotic cells. This poses the significant challenge of slipping a DNA or RNA genome past the nuclear pore complex (NPC) embedded in the nuclear envelope. Quantitative fluorescence imaging is shedding new light on this process, with recent data implicating misdelivery of viral genomes at nuclear pores as a bottleneck to virus replication. Here, we infer NPC functions for nuclear import of viral genomes from cell biology experiments and explore potential causes of misdelivery, including improper virus docking at NPCs, incomplete translocation, virus-induced stress and innate immunity reactions. We conclude by discussing consequences of viral genome misdelivery for viruses and host cells, and lay out future questions to enhance our understanding of this phenomenon. Further studies into viral genome misdelivery may reveal unexpected aspects about NPC structure and function, as well as aid in developing strategies for controlling viral infections to improve human health.
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Murine Gammaherpesvirus 68 Pathogenesis Is Independent of Caspase-1 and Caspase-11 in Mice and Impairs Interleukin-1β Production upon Extrinsic Stimulation in Culture. J Virol 2015; 89:6562-74. [PMID: 25855746 DOI: 10.1128/jvi.00658-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 04/02/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Gammaherpesviruses establish lifelong infections that are associated with the development of cancer. These viruses subvert many aspects of the innate and adaptive immune response of the host. The inflammasome, a macromolecular protein complex that controls inflammatory responses to intracellular danger signals generated by pathogens, is both activated and subverted during human gammaherpesvirus infection in culture. The impact of the inflammasome response on gammaherpesvirus replication and latency in vivo is not known. Caspase-1 is the inflammasome effector protease that cleaves the proinflammatory cytokines interleukin-1β (IL-1β) and IL-18. We infected caspase-1-deficient mice with murine gammaherpesvirus 68 (MHV68) and observed no impact on acute replication in the lung or latency and reactivation from latency in the spleen. This led us to examine the effect of viral infection on inflammasome responses in bone marrow-derived macrophages. We determined that infection of macrophages with MHV68 led to a robust interferon response but failed to activate caspase-1 or induce the secretion of IL-1β. In addition, MHV68 infection led to a reduction in IL-1β production after extrinsic lipopolysaccharide stimulation or upon coinfection with Salmonella enterica serovar Typhimurium. Interestingly, this impairment occurred at the proIL-1β transcript level and was independent of the RTA, the viral lytic replication and transcription activator. Taken together, MHV68 impairs the inflammasome response by inhibiting IL-1β production during the initial stages of infection. IMPORTANCE Gammaherpesviruses persist for the lifetime of the host. To accomplish this, they must evade recognition and clearance by the immune system. The inflammasome consists of proteins that detect foreign molecules in the cell and respond by secreting proinflammatory signaling proteins that recruit immune cells to clear the infection. Unexpectedly, we found that murine gammaherpesvirus pathogenesis was not enhanced in mice lacking caspase-1, a critical inflammasome component. This led us to investigate whether the virus actively impairs the inflammasome response. We found that the inflammasome was not activated upon macrophage cell infection with murine gammaherpesvirus 68. Infection also prevented the host cell inflammasome response to other pathogen-associated molecular patterns, indicated by reduced production of the proinflammatory cytokine IL-1β upon bacterial coinfection. Taken together, murine gammaherpesvirus impairment of the inflammatory cytokine IL-1β in macrophages identifies one mechanism by which the virus may inhibit caspase-1-dependent immune responses in the infected animal.
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Sun C, Schattgen SA, Pisitkun P, Jorgensen JP, Hilterbrand AT, Wang LJ, West JA, Hansen K, Horan KA, Jakobsen MR, O'Hare P, Adler H, Sun R, Ploegh HL, Damania B, Upton JW, Fitzgerald KA, Paludan SR. Evasion of innate cytosolic DNA sensing by a gammaherpesvirus facilitates establishment of latent infection. THE JOURNAL OF IMMUNOLOGY 2015; 194:1819-31. [PMID: 25595793 DOI: 10.4049/jimmunol.1402495] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Herpesviruses are DNA viruses harboring the capacity to establish lifelong latent-recurrent infections. There is limited knowledge about viruses targeting the innate DNA-sensing pathway, as well as how the innate system impacts on the latent reservoir of herpesvirus infections. In this article, we report that murine gammaherpesvirus 68 (MHV68), in contrast to α- and β-herpesviruses, induces very limited innate immune responses through DNA-stimulated pathways, which correspondingly played only a minor role in the control of MHV68 infections in vivo. Similarly, Kaposi's sarcoma-associated herpesvirus also did not stimulate immune signaling through the DNA-sensing pathways. Interestingly, an MHV68 mutant lacking deubiquitinase (DUB) activity, embedded within the large tegument protein open reading frame (ORF)64, gained the capacity to stimulate the DNA-activated stimulator of IFN genes (STING) pathway. We found that ORF64 targeted a step in the DNA-activated pathways upstream of the bifurcation into the STING and absent in melanoma 2 pathways, and lack of the ORF64 DUB was associated with impaired delivery of viral DNA to the nucleus, which, instead, localized to the cytoplasm. Correspondingly, the ORF64 DUB active site mutant virus exhibited impaired ability to establish latent infection in wild-type, but not STING-deficient, mice. Thus, gammaherpesviruses evade immune activation by the cytosolic DNA-sensing pathway, which, in the MHV68 model, facilitates establishment of infections.
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Affiliation(s)
- Chenglong Sun
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark; Aarhus Research Center for Innate Immunology, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Stefan A Schattgen
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01655
| | - Prapaporn Pisitkun
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark; Aarhus Research Center for Innate Immunology, Aarhus University, DK-8000 Aarhus C, Denmark; Department of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand 10400
| | - Joan P Jorgensen
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark; Aarhus Research Center for Innate Immunology, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Adam T Hilterbrand
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712
| | - Lucas J Wang
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712
| | - John A West
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599
| | - Kathrine Hansen
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark; Aarhus Research Center for Innate Immunology, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Kristy A Horan
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Martin R Jakobsen
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark; Aarhus Research Center for Innate Immunology, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Peter O'Hare
- Section of Virology, Faculty of Medicine, Imperial College, St. Mary's Campus, London W2 1PG, United Kingdom
| | - Heiko Adler
- Helmholtz Zentrum Munich, German Research Center for Environmental Health, D-81377 Munich, Germany
| | - Ren Sun
- Department of Molecular Biology and Medical Pharmacology, Faculty of Medicine, University of California, Los Angeles, Los Angeles, CA 90095; and
| | - Hidde L Ploegh
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142
| | - Blossom Damania
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599
| | - Jason W Upton
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712
| | - Katherine A Fitzgerald
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01655
| | - Søren R Paludan
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark; Aarhus Research Center for Innate Immunology, Aarhus University, DK-8000 Aarhus C, Denmark;
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Interplay between Kaposi's sarcoma-associated herpesvirus and the innate immune system. Cytokine Growth Factor Rev 2014; 25:597-609. [PMID: 25037686 DOI: 10.1016/j.cytogfr.2014.06.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 06/16/2014] [Indexed: 02/04/2023]
Abstract
Understanding of the innate immune response to viral infections is rapidly progressing, especially with regards to the detection of DNA viruses. Kaposi's sarcoma-associated herpesvirus (KSHV) is a large dsDNA virus that is responsible for three human diseases: Kaposi's sarcoma, primary effusion lymphoma and multicentric Castleman's disease. The major target cells of KSHV (B cells and endothelial cells) express a wide range of pattern recognition receptors (PRRs) and play a central role in mobilizing inflammatory responses. On the other hand, KSHV encodes an array of immune evasion genes, including several pirated host genes, which interfere with multiple aspects of the immune response. This review summarizes current understanding of innate immune recognition of KSHV and the role of immune evasion genes that shape the antiviral and inflammatory responses.
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15
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The gammaherpesviruses Kaposi's sarcoma-associated herpesvirus and murine gammaherpesvirus 68 modulate the Toll-like receptor-induced proinflammatory cytokine response. J Virol 2014; 88:9245-59. [PMID: 24899179 DOI: 10.1128/jvi.00841-14] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The human pathogen Kaposi's sarcoma-associated herpesvirus (KSHV), the etiological agent of Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease, establishes lifelong latency upon infection. Murine gammaherpesvirus 68 (MHV68) is a well-established model for KSHV. Toll-like receptors (TLRs) play a crucial role for the innate immune response to pathogens. Although KSHV and MHV68 are detected by TLRs, studies suggest they modulate TLR4 and TLR9 signaling, respectively. In this study, we show that in bone marrow-derived macrophages (BMDMs), MHV68 did not induce a detectable proinflammatory cytokine response. Furthermore, MHV68 abrogated the response to TLR2, -4, -7, and -9 agonists in BMDMs. Similarly to observations with MHV68, infection with KSHV efficiently inhibited TLR2 signaling in THP-1 monocytes. Using a KSHV open reading frame (ORF) library, we found that K4.2, ORF21, ORF31, and the replication and transcription activator protein (RTA)/ORF50 inhibited TLR2-dependent nuclear factor kappa B (NF-κB) activation in HEK293 TLR2-yellow fluorescent protein (YFP)- and Flag-TLR2-transfected HEK293T cells. Of the identified ORFs, RTA/ORF50 strongly downregulated TLR2 and TLR4 signaling by reducing TLR2 and TLR4 protein expression. Confocal microscopy revealed that TLR2 and TLR4 were no longer localized to the plasma membrane in cells expressing RTA/ORF50. In this study, we have shown that the gammaherpesviruses MHV68 and KSHV efficiently downmodulate TLR signaling in macrophages and have identified a novel function of RTA/ORF50 in modulation of the innate immune response. IMPORTANCE The Toll-like receptors (TLRs) are an important class of pattern recognition receptors of the innate immune system. They induce a potent proinflammatory cytokine response upon detection of a variety of pathogens. In this study, we found that the gammaherpesviruses murine gammaherpesvirus 68 (MHV68) and Kaposi's sarcoma-associated herpesvirus (KSHV) efficiently inhibit the TLR-mediated innate immune response. We further identified the KSHV-encoded replication and transcription activator protein (RTA) as a novel modulator of TLR signaling. Our data suggest that the gammaherpesviruses MHV68 and KSHV prevent activation of the innate immune response by targeting TLR signaling.
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Quantitative theory of entropic forces acting on constrained nucleotide sequences applied to viruses. Proc Natl Acad Sci U S A 2014; 111:5054-9. [PMID: 24639520 DOI: 10.1073/pnas.1402285111] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
We outline a theory to quantify the interplay of entropic and selective forces on nucleotide organization and apply it to the genomes of single-stranded RNA viruses. We quantify these forces as intensive variables that can easily be compared between sequences, outline a computationally efficient transfer-matrix method for their calculation, and apply this method to influenza and HIV viruses. We find viruses altering their dinucleotide motif use under selective forces, with these forces on CpG dinucleotides growing stronger in influenza the longer it replicates in humans. For a subset of genes in the human genome, many involved in antiviral innate immunity, the forces acting on CpG dinucleotides are even greater than the forces observed in viruses, suggesting that both effects are in response to similar selective forces involving the innate immune system. We further find that the dynamics of entropic forces balancing selective forces can be used to predict how long it will take a virus to adapt to a new host, and that it would take H1N1 several centuries to adapt to humans from birds, typically contributing many of its synonymous substitutions to the forcible removal of CpG dinucleotides. By examining the probability landscape of dinucleotide motifs, we predict where motifs are likely to appear using only a single-force parameter and uncover the localization of UpU motifs in HIV. Essentially, we extend the natural language and concepts of statistical physics, such as entropy and conjugated forces, to understanding viral sequences and, more generally, constrained genome evolution.
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Gauld SB, De Santis JL, Kulinski JM, McGraw JA, Leonardo SM, Ruder EA, Maier W, Tarakanova VL. Modulation of B-cell tolerance by murine gammaherpesvirus 68 infection: requirement for Orf73 viral gene expression and follicular helper T cells. Immunology 2013; 139:197-204. [PMID: 23311955 DOI: 10.1111/imm.12069] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 01/07/2013] [Accepted: 01/08/2013] [Indexed: 12/22/2022] Open
Abstract
Viruses such as Epstein-Barr virus (EBV) have been linked to mechanisms that support autoantibody production in diseases such as systemic lupus erythematosus. However, the mechanisms by which viruses contribute to autoantibody production remain poorly defined. This stems in part, from the high level of seropositivity for EBV (> 95%) and the exquisite species specificity of EBV. In this study we overcame these problems by using murine gammaherpesvirus 68 (MHV68), a virus genetically and biologically related to EBV. We first showed that MHV68 drives autoantibody production by promoting a loss of B-cell anergy. We next showed that MHV68 infection resulted in the expansion of follicular helper T (Tfh) cells in vivo, and that these Tfh cells supported autoantibody production and a loss of B-cell anergy. Finally, we showed that the expansion of Tfh cells and autoantibody production was dependent on the establishment of viral latency and expression of a functional viral gene called Orf73. Collectively, our studies highlighted an unexpected role for viral latency in the development of autoantibodies following MHV68 infection and suggest that virus-induced expansion of Tfh cells probably plays a key role in the loss of B-cell anergy.
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Affiliation(s)
- Stephen B Gauld
- Medical College of Wisconsin, Division of Allergy/Immunology, Department of Pediatrics, The Children's Research Institute, Milwaukee, WI, USA.
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Moresco EMY, Beutler B. Resisting viral infection: the gene by gene approach. Curr Opin Virol 2011; 1:513-8. [PMID: 22440911 DOI: 10.1016/j.coviro.2011.10.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 10/05/2011] [Accepted: 10/07/2011] [Indexed: 01/18/2023]
Abstract
This review focuses on genes required for resistance to mouse cytomegalovirus (MCMV), as identified through unbiased genetic screening. Components of the developmental, sensing, and effector pathways, functioning in multiple cell types, were detected by infecting 22,000 G3 mutant mice with MCMV at an inoculum easily contained by WT animals. Merging these findings with discoveries from hypothesis-based studies, we present a cohesive picture of the essential elements utilized by the mouse innate immune system to counter MCMV. We believe that many breakthrough discoveries will yet be made using a classical genetic approach.
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Affiliation(s)
- Eva Marie Y Moresco
- Department of Genetics, The Scripps Research Institute, La Jolla, CA 92037, USA
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19
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Arpaia N, Barton GM. Toll-like receptors: key players in antiviral immunity. Curr Opin Virol 2011; 1:447-54. [PMID: 22440908 DOI: 10.1016/j.coviro.2011.10.006] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Accepted: 10/08/2011] [Indexed: 12/24/2022]
Abstract
TLRs are a family of innate receptors whose specificities are predetermined in the germline. Therefore, TLRs have evolved to recognize conserved features of microbes. Viruses typically lack the conserved features common to other pathogen classes, so the innate immune system has evolved to recognize viral nucleic acid as a hallmark of viral infection. In this review we discuss examples of TLR-mediated viral recognition and the functional consequences of this recognition for antiviral immunity.
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Affiliation(s)
- Nicholas Arpaia
- Division of Immunology & Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200, USA
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