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Li S, Xie Y, Yu C, Zheng C, Xu Z. The battle between host antiviral innate immunity and immune evasion by cytomegalovirus. Cell Mol Life Sci 2024; 81:341. [PMID: 39120730 PMCID: PMC11335264 DOI: 10.1007/s00018-024-05369-y] [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: 05/23/2024] [Revised: 07/10/2024] [Accepted: 07/17/2024] [Indexed: 08/10/2024]
Abstract
Cytomegalovirus (CMV) has successfully established a long-lasting latent infection in humans due to its ability to counteract the host antiviral innate immune response. During coevolution with the host, the virus has evolved various evasion techniques to evade the host's innate immune surveillance. At present, there is still no vaccine available for the prevention and treatment of CMV infection, and the interaction between CMV infection and host antiviral innate immunity is still not well understood. However, ongoing studies will offer new insights into how to treat and prevent CMV infection and its related diseases. Here, we update recent studies on how CMV evades antiviral innate immunity, with a focus on how CMV proteins target and disrupt critical adaptors of antiviral innate immune signaling pathways. This review also discusses some classic intrinsic cellular defences that are crucial to the fight against viral invasion. A comprehensive review of the evasion mechanisms of antiviral innate immunity by CMV will help investigators identify new therapeutic targets and develop vaccines against CMV infection.
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Affiliation(s)
- Shuang Li
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Yuanyang Xie
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Changyin Yu
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China.
- The Collaborative Innovation Center of Tissue Damage Repair and Regeneration Medicine, Zunyi Medical University, Zunyi, China.
| | - Chunfu Zheng
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada.
| | - Zucai Xu
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China.
- The Collaborative Innovation Center of Tissue Damage Repair and Regeneration Medicine, Zunyi Medical University, Zunyi, China.
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Rollman TB, Berkebile ZW, Okae H, Bardwell VJ, Gearhart MD, Bierle CJ. Human trophoblast stem cells restrict human cytomegalovirus replication. J Virol 2024; 98:e0193523. [PMID: 38451085 PMCID: PMC11019952 DOI: 10.1128/jvi.01935-23] [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: 12/11/2023] [Accepted: 02/18/2024] [Indexed: 03/08/2024] Open
Abstract
Placental infection plays a central role in the pathogenesis of congenital human cytomegalovirus (HCMV) infections and is a cause of fetal growth restriction and pregnancy loss. HCMV can replicate in some trophoblast cell types, but it remains unclear how the virus evades antiviral immunity in the placenta and how infection compromises placental development and function. Human trophoblast stem cells (TSCs) can be differentiated into extravillous trophoblasts (EVTs), syncytiotrophoblasts (STBs), and organoids, and this study assessed the utility of TSCs as a model of HCMV infection in the first-trimester placenta. HCMV was found to non-productively infect TSCs, EVTs, and STBs. Immunofluorescence assays and flow cytometry experiments further revealed that infected TSCs frequently only express immediate early viral gene products. Similarly, RNA sequencing found that viral gene expression in TSCs does not follow the kinetic patterns observed during lytic infection in fibroblasts. Canonical antiviral responses were largely not observed in HCMV-infected TSCs and TSC-derived trophoblasts. Rather, infection dysregulated factors involved in cell identity, differentiation, and Wingless/Integrated signaling. Thus, while HCMV does not replicate in TSCs, infection may perturb trophoblast differentiation in ways that could interfere with placental function. IMPORTANCE Placental infection plays a central role in human cytomegalovirus (HCMV) pathogenesis during pregnancy, but the species specificity of HCMV and the limited availability and lifespan of primary trophoblasts have been persistent barriers to understanding how infection impacts this vital organ. Human trophoblast stem cells (TSCs) represent a new approach to modeling viral infection early in placental development. This study reveals that TSCs, like other stem cell types, restrict HCMV replication. However, infection perturbs the expression of genes involved in differentiation and cell fate determination, pointing to a mechanism by which HCMV could cause placental injury.
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Affiliation(s)
- Tyler B. Rollman
- Division of Pediatric Infectious Diseases, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Zachary W. Berkebile
- Division of Pediatric Infectious Diseases, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Hiroaki Okae
- Department of Informative Genetics, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Vivian J. Bardwell
- Developmental Biology Center, Department of Genetics, Cell Biology and Development and the Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, USA
| | - Micah D. Gearhart
- Department of Obstetrics, Gynecology and Women’s Health, University of Minnesota, Minneapolis, Minnesota, USA
| | - Craig J. Bierle
- Division of Pediatric Infectious Diseases, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, USA
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Rollman TB, Berkebile ZW, Okae H, Bardwell VJ, Gearhart MD, Bierle CJ. Human Trophoblast Stem Cells Restrict Human Cytomegalovirus Replication. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.13.571456. [PMID: 38168202 PMCID: PMC10760179 DOI: 10.1101/2023.12.13.571456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Placental infection plays a central role in the pathogenesis of congenital human cytomegalovirus (HCMV) infections and is a cause of fetal growth restriction and pregnancy loss. HCMV can replicate in some trophoblast cell types, but it remains unclear how the virus evades antiviral immunity in the placenta and how infection compromises placental development and function. Human trophoblast stem cells (TSCs) can be differentiated into extravillous trophoblasts (EVTs), syncytiotrophoblasts (STBs), and organoids, and this study assessed the utility of TSCs as a model of HCMV infection in the first trimester placenta. HCMV was found to non-productively infect TSCs, EVTs, and STBs. Immunofluorescence assays and flow cytometry experiments further revealed that infected TSCs frequently only express immediate early viral gene products. Similarly, RNA-sequencing found that viral gene expression in TSCs does not follow the kinetic patterns observed during lytic infection in fibroblasts. Canonical antiviral responses were largely not observed in HCMV-infected TSCs and TSC-derived trophoblasts. Rather, infection dysregulated factors involved in cell identity, differentiation, and WNT signaling. Thus, while HCMV does not replicate in TSCs, infection may perturb trophoblast differentiation in ways that could interfere with placental function. Importance Placental infection plays a central role in HCMV pathogenesis during pregnancy, but the species-specificity of HCMV and the limited availability and lifespan of primary trophoblasts have been persistent barriers to understanding how infection impacts this vital organ. Human TSCs represent a new approach to modeling viral infection early in placental development. This study reveals that TSCs, like other stem cell types, restrict HCMV replication. However, infection perturbs the expression of genes involved in differentiation and cell fate determination, pointing to a mechanism by which HCMV could cause placental injury.
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Characterization of the Second Apoptosis Inhibitor Encoded by Guinea Pig Cytomegalovirus. J Virol 2022; 96:e0162222. [PMID: 36472439 PMCID: PMC9769370 DOI: 10.1128/jvi.01622-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Despite the usefulness of guinea pig cytomegalovirus (GPCMV) for studies on congenital CMV infection, its viral mechanisms for the evasion of host defense strategies have not been fully elucidated. We reported previously that GPCMV gp38.1 functions as a viral mitochondria-localized inhibitor of apoptosis-like function, and its weak activity suggested the presence of an additional inhibitory molecule(s). Here, we identified gp38.3-2, a 42-amino-acid (aa) reading frame embedded within the gp38.3 gene that encodes a positional homolog of murine CMV (MCMV) m41. Characterization of gp38.3-2 resulted in the following findings: (i) the aa sequence of gp38.3-2 shows some similarity to that of MCMV m41.1, a viral inhibitor of oligomerization of a member of Bcl-2 family protein BAK, but there is no correspondence in their predicted secondary structures; (ii) gp38.3-2, but not gp38.3, showed inhibitory activities against staurosporine-induced apoptosis; (iii) three-dimensional protein complex prediction suggests that the N-terminal α-helix of gp38.3-2 interacts with residues in the BH3 and BH1 motifs of BAK, and analysis of gp38.3-2 and BAK mutants supported this model; (iv) guinea pig fibroblast cells infected with gp38.3-2-deficient GPCMV strain Δ38.3-2 died earlier than cells infected with rescued strain r38.3-2, resulting in lower yields of Δ38.3-2; (v) Δ38.3-2 exhibited a partial but significant decrease in monocyte and macrophage infection in comparison with r38.3-2; and, however, (vi) little difference in the viral infection of guinea pigs was observed between these two strains. Therefore, we hypothesize that gp38.3-2 contributes little to the evasion of host defense mechanisms under the experimental conditions used. IMPORTANCE Although GPCMV provides a useful animal model for studies on the pathogenesis of congenital CMV infection and the development of CMV vaccine strategies, our understanding of the viral mechanisms by which it evades apoptosis of infected cells has been limited in comparison with those of murine and human CMVs. Here, we report a second GPCMV apoptosis inhibitor (42 amino acids in length) that interacts with BAK, a Bcl-2 family proapoptotic protein. Three-dimensional structural prediction indicated a unique BAK recognition by gp38.3-2 via the BH3 and BH1 motif sequences. Our findings suggest the potential development of BH3 mimetics that can regulate inhibition or induction of apoptosis based on short ~40-amino-acid peptide molecules as with GPCMV.
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Olson AT, Child SJ, Geballe AP. Antagonism of Protein Kinase R by Large DNA Viruses. Pathogens 2022; 11:pathogens11070790. [PMID: 35890034 PMCID: PMC9319463 DOI: 10.3390/pathogens11070790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/06/2022] [Accepted: 07/07/2022] [Indexed: 12/02/2022] Open
Abstract
Decades of research on vaccinia virus (VACV) have provided a wealth of insights and tools that have proven to be invaluable in a broad range of studies of molecular virology and pathogenesis. Among the challenges that viruses face are intrinsic host cellular defenses, such as the protein kinase R pathway, which shuts off protein synthesis in response to the dsRNA that accumulates during replication of many viruses. Activation of PKR results in phosphorylation of the α subunit of eukaryotic initiation factor 2 (eIF2α), inhibition of protein synthesis, and limited viral replication. VACV encodes two well-characterized antagonists, E3L and K3L, that can block the PKR pathway and thus enable the virus to replicate efficiently. The use of VACV with a deletion of the dominant factor, E3L, enabled the initial identification of PKR antagonists encoded by human cytomegalovirus (HCMV), a prevalent and medically important virus. Understanding the molecular mechanisms of E3L and K3L function facilitated the dissection of the domains, species-specificity, and evolutionary potential of PKR antagonists encoded by human and nonhuman CMVs. While remaining cognizant of the substantial differences in the molecular virology and replication strategies of VACV and CMVs, this review illustrates how VACV can provide a valuable guide for the study of other experimentally less tractable viruses.
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Affiliation(s)
- Annabel T. Olson
- Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Center, 1100 Fairview Ave N Seattle, P.O. Box 19024, Seattle, WA 98109, USA; (A.T.O.); (S.J.C.)
- Departments of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - Stephanie J. Child
- Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Center, 1100 Fairview Ave N Seattle, P.O. Box 19024, Seattle, WA 98109, USA; (A.T.O.); (S.J.C.)
| | - Adam P. Geballe
- Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Center, 1100 Fairview Ave N Seattle, P.O. Box 19024, Seattle, WA 98109, USA; (A.T.O.); (S.J.C.)
- Departments of Microbiology, University of Washington, Seattle, WA 98195, USA
- Departments of Medicine, University of Washington, Seattle, WA 98195, USA
- Correspondence:
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Schleiss MR, Fernández-Alarcón C, Hernandez-Alvarado N, Wang JB, Geballe AP, McVoy MA. Inclusion of the Guinea Pig Cytomegalovirus Pentameric Complex in a Live Virus Vaccine Aids Efficacy against Congenital Infection but Is Not Essential for Improving Maternal and Neonatal Outcomes. Viruses 2021; 13:v13122370. [PMID: 34960639 PMCID: PMC8706200 DOI: 10.3390/v13122370] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 11/19/2021] [Accepted: 11/20/2021] [Indexed: 01/17/2023] Open
Abstract
The development of a vaccine against congenital human cytomegalovirus (HCMV) infection is a major priority. The pentameric complex (PC) of virion envelope proteins gH, gL, UL128, UL130, and UL131A is a key vaccine target. To determine the importance of immunity to the homologous PC encoded by guinea pig cytomegalovirus (GPCMV) in preventing congenital CMV, PC-intact and PC-deficient live-attenuated vaccines were generated and directly compared for immunogenicity and efficacy against vertical transmission in a vertical transmission model. A virulent PC-intact GPCMV (PC/intact) was modified by galK mutagenesis either to abrogate PC expression (PC/null; containing a frame-shift mutation in GP129, homolog of UL128) or to delete genes encoding three MHC Class I homologs and a protein kinase R (PKR) evasin while retaining the PC (3DX/Δ145). Attenuated vaccines were compared to sham immunization in a two-dose preconception subcutaneous inoculation regimen in GPCMV seronegative Hartley guinea pigs. Vaccines induced transient, low-grade viremia in 5/12 PC/intact-, 2/12 PC/null-, and 1/11 3DX/Δ145-vaccinated animals. Upon completion of the two-dose vaccine series, ELISA titers for the PC/intact group (geometic mean titer (GMT) 13,669) were not significantly different from PC/null (GMT 8127) but were significantly higher than for the 3DX/Δ145 group (GMT 6185; p < 0.01). Dams were challenged with salivary gland-adapted GPCMV in the second trimester. All vaccines conferred protection against maternal viremia. Newborn weights were significantly lower in sham-immunized controls (84.5 ± 2.4 g) compared to PC/intact (96 ± 2.3 g), PC/null (97.6 ± 1.9 g), or 3DX/Δ145 (93 ± 1.7) pups (p < 0.01). Pup mortality in sham-immunized controls was 29/40 (73%) and decreased to 1/44 (2.3%), 2/46 (4.3%), or 4/40 (10%) in PC/intact, PC/null, or 3DX/Δ145 groups, respectively (all p < 0.001 compared to control). Congenital GPCMV transmission occurred in 5/44 (11%), 16/46 (35%), or 29/38 (76%) of pups in PC/intact, PC/null, or 3DX/Δ145 groups, versus 36/40 (90%) in controls. For infected pups, viral loads were lower in pups born to vaccinated dams compared to controls. Sequence analysis demonstrated that infected pups in the vaccine groups had salivary gland-adapted GPCMV and not vaccine strain-specific sequences, indicating that congenital transmission was due to the challenge virus and not vaccine virus. We conclude that inclusion of the PC in a live, attenuated preconception vaccine improves immunogenicity and reduces vertical transmission, but PC-null vaccines are equal to PC-intact vaccines in reducing maternal viremia and protecting against GPCMV-related pup mortality.
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Affiliation(s)
- Mark R. Schleiss
- Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN 55455, USA; (C.F.-A.); (N.H.-A.)
- Correspondence: ; Tel.: +1-612-626-9913
| | - Claudia Fernández-Alarcón
- Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN 55455, USA; (C.F.-A.); (N.H.-A.)
| | - Nelmary Hernandez-Alvarado
- Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN 55455, USA; (C.F.-A.); (N.H.-A.)
| | - Jian Ben Wang
- Department of Pediatrics, Virginia Commonwealth University, Richmond, VA 23298, USA; (J.B.W.); (M.A.M.)
| | - Adam P. Geballe
- Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA;
| | - Michael A. McVoy
- Department of Pediatrics, Virginia Commonwealth University, Richmond, VA 23298, USA; (J.B.W.); (M.A.M.)
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Senkevich TG, Yutin N, Wolf YI, Koonin EV, Moss B. Ancient Gene Capture and Recent Gene Loss Shape the Evolution of Orthopoxvirus-Host Interaction Genes. mBio 2021; 12:e0149521. [PMID: 34253028 PMCID: PMC8406176 DOI: 10.1128/mbio.01495-21] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 05/24/2021] [Indexed: 01/27/2023] Open
Abstract
The survival of viruses depends on their ability to resist host defenses and, of all animal virus families, the poxviruses have the most antidefense genes. Orthopoxviruses (ORPV), a genus within the subfamily Chordopoxvirinae, infect diverse mammals and include one of the most devastating human pathogens, the now eradicated smallpox virus. ORPV encode ∼200 genes, of which roughly half are directly involved in virus genome replication and expression as well as virion morphogenesis. The remaining ∼100 "accessory" genes are responsible for virus-host interactions, particularly counter-defense of innate immunity. Complete sequences are currently available for several hundred ORPV genomes isolated from a variety of mammalian hosts, providing a rich resource for comparative genomics and reconstruction of ORPV evolution. To identify the provenance and evolutionary trends of the ORPV accessory genes, we constructed clusters including the orthologs of these genes from all chordopoxviruses. Most of the accessory genes were captured in three major waves early in chordopoxvirus evolution, prior to the divergence of ORPV and the sister genus Centapoxvirus from their common ancestor. The capture of these genes from the host was followed by extensive gene duplication, yielding several paralogous gene families. In addition, nine genes were gained during the evolution of ORPV themselves. In contrast, nearly every accessory gene was lost, some on multiple, independent occasions in numerous lineages of ORPV, so that no ORPV retains them all. A variety of functional interactions could be inferred from examination of pairs of ORPV accessory genes that were either often or rarely lost concurrently. IMPORTANCE Orthopoxviruses (ORPV) include smallpox (variola) virus, one of the most devastating human pathogens, and vaccinia virus, comprising the vaccine used for smallpox eradication. Among roughly 200 ORPV genes, about half are essential for genome replication and expression as well as virion morphogenesis, whereas the remaining half consists of accessory genes counteracting the host immune response. We reannotated the accessory genes of ORPV, predicting the functions of uncharacterized genes, and reconstructed the history of their gain and loss during the evolution of ORPV. Most of the accessory genes were acquired in three major waves antedating the origin of ORPV from chordopoxviruses. The evolution of ORPV themselves was dominated by gene loss, with numerous genes lost at the base of each major group of ORPV. Examination of pairs of ORPV accessory genes that were either often or rarely lost concurrently during ORPV evolution allows prediction of different types of functional interactions.
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Affiliation(s)
- Tatiana G. Senkevich
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Instutes of Health, Bethesda, Maryland, USA
| | - Natalya Yutin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA
| | - Yuri I. Wolf
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA
| | - Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA
| | - Bernard Moss
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Instutes of Health, Bethesda, Maryland, USA
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Noguchi K, Majima R, Takahashi K, Iwase Y, Yamada S, Satoh K, Koshizuka T, Inoue N. Identification and functional analyses of a cell-death inhibitor encoded by guinea pig cytomegalovirus gp38.1 in cell culture and in animals. J Gen Virol 2020; 101:1270-1279. [PMID: 32915127 DOI: 10.1099/jgv.0.001493] [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] [Indexed: 11/18/2022] Open
Abstract
Cytomegaloviruses (CMVs) employ an array of strategies designed to interfere with host defence responses against pathogens. Studies on such evasion mechanisms are important for understanding the pathogenesis of CMV diseases. Although guinea pig CMV (GPCMV) provides a useful animal model for congenital CMV infection, its evasion strategies are not fully elucidated. Here, we analysed a genome locus that may encode gene products for the GPCMV evasion mechanisms and found the following. (1) RACE analyses identified five transcripts in the GP38-gp38.4 locus, one of which was a spliced product encoding gp38.1. Similarities in the splicing pattern and gene position of gp38.1 to human CMV UL37 and its exon 1 encoding vMIA (viral mitochondria-localized inhibitor of apoptosis) suggest that the gp38.1 gene encodes an apoptosis inhibitor. (2) In a transient transfection assay, gp38.1 localized in the mitochondria and relocated BAX from the cytoplasm to the mitochondria, although its co-localization with BAK was not evident. Further, the expression of gp38.1 partially reduced staurosporine-induced apoptosis. (3) GPCMV defective in the gp38.1 ORF (Δ38.1) and the virus that rescues the defect (r38.1) were generated. Guinea pig fibroblast cells infected with Δ38.1 died earlier than r38.1-infected cells, which resulted in the lower yields of Δ38.1. (4) In animals, viral loads in the spleens of r38.1-infected guinea pigs were higher than those in the spleens of Δ38.1-infected animals. In conclusion, although GPCMV gp38.1 exerts a vMIA-like function, its inhibitory effect was not robust, suggesting the presence of additional inhibitory molecule(s), such as a BAK-specific inhibitor.
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Affiliation(s)
- Kazuma Noguchi
- Present address: Kaken Pharmaceutical, Tokyo, Japan
- Microbiology and Immunology, Gifu Pharmaceutical University, Gifu, Japan
| | - Ryuichi Majima
- Microbiology and Immunology, Gifu Pharmaceutical University, Gifu, Japan
| | - Keita Takahashi
- Microbiology and Immunology, Gifu Pharmaceutical University, Gifu, Japan
| | - Yoshihiko Iwase
- Microbiology and Immunology, Gifu Pharmaceutical University, Gifu, Japan
| | - Souichi Yamada
- Department of Virology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Keisuke Satoh
- Microbiology and Immunology, Gifu Pharmaceutical University, Gifu, Japan
| | - Tetsuo Koshizuka
- Microbiology and Immunology, Gifu Pharmaceutical University, Gifu, Japan
| | - Naoki Inoue
- Microbiology and Immunology, Gifu Pharmaceutical University, Gifu, Japan
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Roark HK, Jenks JA, Permar SR, Schleiss MR. Animal Models of Congenital Cytomegalovirus Transmission: Implications for Vaccine Development. J Infect Dis 2020; 221:S60-S73. [PMID: 32134481 PMCID: PMC7057791 DOI: 10.1093/infdis/jiz484] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Although cytomegaloviruses (CMVs) are species-specific, the study of nonhuman CMVs in animal models can help to inform and direct research aimed at developing a human CMV (HCMV) vaccine. Because the driving force behind the development of HCMV vaccines is to prevent congenital infection, the animal model in question must be one in which vertical transmission of virus occurs to the fetus. Fortunately, two such animal models-the rhesus macaque CMV and guinea pig CMV-are characterized by congenital infection. Hence, each model can be evaluated in "proof-of-concept" studies of preconception vaccination aimed at blocking transplacental transmission. This review focuses on similarities and differences in the respective model systems, and it discusses key insights from each model germane to the study of HCMV vaccines.
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Affiliation(s)
- Hunter K Roark
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, North Carolina, USA
| | - Jennifer A Jenks
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, North Carolina, USA
| | - Sallie R Permar
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, North Carolina, USA
| | - Mark R Schleiss
- Center for Infectious Diseases and Microbiology Translational Research, University of Minnesota Medical School, Department of Pediatrics, Division of Pediatric Infectious Diseases and Immunology, Minneapolis, Minnesota, USA
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Bierle CJ, Fernández-Alarcón C, Hernandez-Alvarado N, Zabeli JC, Janus BC, Putri DS, Schleiss MR. Assessing Zika virus replication and the development of Zika-specific antibodies after a mid-gestation viral challenge in guinea pigs. PLoS One 2017; 12:e0187720. [PMID: 29099873 PMCID: PMC5669436 DOI: 10.1371/journal.pone.0187720] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 10/24/2017] [Indexed: 11/18/2022] Open
Abstract
Primary Zika virus (ZIKV) infections that occur during pregnancy can cause spontaneous abortion and profoundly disrupt fetal development. While the full range of developmental abnormalities associated with congenital Zika syndrome is not yet known, severe cases of the syndrome can present with microcephaly, extensive neurologic and ocular damage, and pronounced joint malformations. Animal models that accurately recapitulate congenital Zika syndrome are urgently needed for vaccine development and for the study of ZIKV pathogenesis. As guinea pigs have successfully been used to model transplacental infections by cytomegalovirus, syphilis, and Listeria monocytogenes, we sought to test whether ZIKV could productively infect guinea pigs and whether viral transmission with attendant fetal pathology would occur after a mid-gestation viral challenge. We found that guinea pig cells supported ZIKV replication in vitro. Experimental infection of non-pregnant animals did not result in overt disease but low-level, detectable viremia was observed. When pregnant guinea pigs were challenged with ZIKV at between 18 and 21 days gestational age, ZIKV was not detected in maternal or pup blood, plasma, or tissues and no significant differences in maternal weight gain or pup size were observed following challenge. Nonetheless, a robust antibody response against ZIKV was detected in both the pups and dams. These results suggest that, while guinea pigs can model aspects of the immune response to ZIKV infection during pregnancy, naturally circulating ZIKV strains are not pathogenic during the pregnancy of immunocompetent guinea pigs and do not interfere with normal pup development.
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Affiliation(s)
- Craig J. Bierle
- Division of Pediatric Infectious Disease and Immunology, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Claudia Fernández-Alarcón
- Division of Pediatric Infectious Disease and Immunology, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Nelmary Hernandez-Alvarado
- Division of Pediatric Infectious Disease and Immunology, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Jason C. Zabeli
- Division of Pediatric Infectious Disease and Immunology, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Bradley C. Janus
- Division of Pediatric Infectious Disease and Immunology, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Dira S. Putri
- Division of Pediatric Infectious Disease and Immunology, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Mark R. Schleiss
- Division of Pediatric Infectious Disease and Immunology, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, United States of America
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Carpentier KS, Esparo NM, Child SJ, Geballe AP. A Single Amino Acid Dictates Protein Kinase R Susceptibility to Unrelated Viral Antagonists. PLoS Pathog 2016; 12:e1005966. [PMID: 27780231 PMCID: PMC5079575 DOI: 10.1371/journal.ppat.1005966] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 09/30/2016] [Indexed: 02/07/2023] Open
Abstract
During millions of years of coevolution with their hosts, cytomegaloviruses (CMVs) have succeeded in adapting to overcome host-specific immune defenses, including the protein kinase R (PKR) pathway. Consequently, these adaptations may also contribute to the inability of CMVs to cross species barriers. Here, we provide evidence that the evolutionary arms race between the antiviral factor PKR and its CMV antagonist TRS1 has led to extensive differences in the species-specificity of primate CMV TRS1 proteins. Moreover, we identify a single residue in human PKR that when mutated to the amino acid present in African green monkey (Agm) PKR (F489S) is sufficient to confer resistance to HCMVTRS1. Notably, this precise molecular determinant of PKR resistance has evolved under strong positive selection among primate PKR alleles and is positioned within the αG helix, which mediates the direct interaction of PKR with its substrate eIF2α. Remarkably, this same residue also impacts sensitivity to K3L, a poxvirus-encoded pseudosubstrate that structurally mimics eIF2α. Unlike K3L, TRS1 has no homology to eIF2α, suggesting that unrelated viral genes have convergently evolved to target this critical region of PKR. Despite its functional importance, the αG helix exhibits extraordinary plasticity, enabling adaptations that allow PKR to evade diverse viral antagonists while still maintaining its critical interaction with eIF2α.
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Affiliation(s)
- Kathryn S. Carpentier
- Departments of Microbiology and Medicine, University of Washington, Seattle Washington, and Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Nicolle M. Esparo
- Departments of Microbiology and Medicine, University of Washington, Seattle Washington, and Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Stephanie J. Child
- Departments of Microbiology and Medicine, University of Washington, Seattle Washington, and Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Adam P. Geballe
- Departments of Microbiology and Medicine, University of Washington, Seattle Washington, and Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, Washington
- * E-mail:
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12
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Targeted Mutagenesis of Guinea Pig Cytomegalovirus Using CRISPR/Cas9-Mediated Gene Editing. J Virol 2016; 90:6989-6998. [PMID: 27226370 DOI: 10.1128/jvi.00139-16] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 05/17/2016] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED The cytomegaloviruses (CMVs) are among the most genetically complex mammalian viruses, with viral genomes that often exceed 230 kbp. Manipulation of cytomegalovirus genomes is largely performed using infectious bacterial artificial chromosomes (BACs), which necessitates the maintenance of the viral genome in Escherichia coli and successful reconstitution of virus from permissive cells after transfection of the BAC. Here we describe an alternative strategy for the mutagenesis of guinea pig cytomegalovirus that utilizes clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9)-mediated genome editing to introduce targeted mutations to the viral genome. Transient transfection and drug selection were used to restrict lytic replication of guinea pig cytomegalovirus to cells that express Cas9 and virus-specific guide RNA. The result was highly efficient editing of the viral genome that introduced targeted insertion or deletion mutations to nonessential viral genes. Cotransfection of multiple virus-specific guide RNAs or a homology repair template was used for targeted, markerless deletions of viral sequence or to introduce exogenous sequence by homology-driven repair. As CRISPR/Cas9 mutagenesis occurs directly in infected cells, this methodology avoids selective pressures that may occur during propagation of the viral genome in bacteria and may facilitate genetic manipulation of low-passage or clinical CMV isolates. IMPORTANCE The cytomegalovirus genome is complex, and viral adaptations to cell culture have complicated the study of infection in vivo Recombineering of viral bacterial artificial chromosomes enabled the study of recombinant cytomegaloviruses. Here we report the development of an alternative approach using CRISPR/Cas9-based mutagenesis in guinea pig cytomegalovirus, a small-animal model of congenital cytomegalovirus disease. CRISPR/Cas9 mutagenesis can introduce the same types of mutations to the viral genome as bacterial artificial chromosome recombineering but does so directly in virus-infected cells. CRISPR/Cas9 mutagenesis is not dependent on a bacterial intermediate, and defined viral mutants can be recovered after a limited number of viral genome replications, minimizing the risk of spontaneous mutation.
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13
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An Evolutionary View of the Arms Race between Protein Kinase R and Large DNA Viruses. J Virol 2016; 90:3280-3. [PMID: 26792736 DOI: 10.1128/jvi.01996-15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
To establish productive infections, viruses must counteract numerous cellular defenses that are poised to recognize viruses as nonself and to activate antiviral pathways. The opposing goals of host and viral factors lead to evolutionary arms races that can be illuminated by evolutionary and computational methods and tested in experimental models. Here we illustrate how this perspective has been contributing to our understanding of the interactions of the protein kinase R pathway with large DNA viruses.
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14
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Braggin JE, Child SJ, Geballe AP. Essential role of protein kinase R antagonism by TRS1 in human cytomegalovirus replication. Virology 2015; 489:75-85. [PMID: 26716879 DOI: 10.1016/j.virol.2015.11.032] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Revised: 11/03/2015] [Accepted: 11/30/2015] [Indexed: 01/13/2023]
Abstract
Human cytomegalovirus (HCMV) lacking TRS1 and IRS1 (HCMV[ΔI/ΔT]) cannot replicate in cell culture. Although both proteins can block the protein kinase R (PKR) pathway, they have multiple other activities and binding partners. It remains unknown which functions are essential for HCMV replication. To investigate this issue, we first identified a TRS1 mutant that is unable to bind to PKR. Like HCMV[ΔI/ΔT], a recombinant HCMV containing this mutant (HCMV[TRS1-Mut 1]) did not replicate in wild-type cells. However, HCMV[ΔI/ΔT] did replicate in cells in which PKR expression was reduced by RNA interference. Moreover, HCMV[ΔI/ΔT] and HCMV[TRS1-Mut 1] replicated to similar levels as virus containing wild-type TRS1 in cell lines in which PKR expression was knocked out by CRISPR/Cas9-mediated genome editing. These results demonstrate that the sole essential function of TRS1 is to antagonize PKR and that its other activities do not substantially enhance HCMV replication, at least in cultured human fibroblasts.
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Affiliation(s)
- Jacquelyn E Braggin
- Department of Microbiology, University of Washington Seattle, WA 98115, United States; Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, United States.
| | - Stephanie J Child
- Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, United States.
| | - Adam P Geballe
- Department of Microbiology, University of Washington Seattle, WA 98115, United States; Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, United States; Department of Medicine, University of Washington, Seattle, WA 98115, United States.
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15
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Vaccination with a Live Attenuated Cytomegalovirus Devoid of a Protein Kinase R Inhibitory Gene Results in Reduced Maternal Viremia and Improved Pregnancy Outcome in a Guinea Pig Congenital Infection Model. J Virol 2015; 89:9727-38. [PMID: 26178990 DOI: 10.1128/jvi.01419-15] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 07/08/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Development of a vaccine to prevent congenital cytomegalovirus infection is a major public health priority. Live vaccines attenuated through mutations targeting viral mechanisms responsible for evasion of host defense may be both safe and efficacious. Safety and vaccine efficacy were evaluated using a guinea pig cytomegalovirus (GPCMV) model. Recombinant GPCMV with a targeted deletion of gp145 (designated Δ145), a viral protein kinase R (PKR) inhibitor, was generated. Attenuation was evaluated following inoculation of 10(7) PFU of Δ145 or parental virus into guinea pigs immunosuppressed with cyclophosphamide. Efficacy was evaluated by immunizing GPCMV-naive guinea pigs twice with either 10(5) or 10(6) PFU of Δ145, establishing pregnancy, and challenging the guinea pigs with salivary gland-adapted GPCMV. The immune response, maternal viral load, pup mortality, and congenital infection rates in the vaccine and control groups were compared. Δ145 was substantially attenuated for replication in immunocompromised guinea pigs. Vaccination with Δ145 induced enzyme-linked immunosorbent assay (ELISA) and neutralizing antibody levels comparable to those achieved in natural infection. In the higher- and lower-dose vaccine groups, pup mortality was reduced to 1/24 (4%) and 4/29 (14%) pups, respectively, whereas it was 26/31 (81%) in unvaccinated control pups (P < 0.0001 for both groups versus the control group). Congenital infection occurred in 20/31 (65%) control pups but only 8/24 (33%) pups in the group vaccinated with 10(6) PFU (P < 0.05). Significant reductions in the magnitude of maternal DNAemia and pup viral load were noted in the vaccine groups compared to those in the controls. Deletion of a GPCMV genome-encoded PKR inhibitor results in a highly attenuated virus that is immunogenic and protective as a vaccine against transplacental infection. IMPORTANCE Previous attempts to develop successful immunization against cytomegalovirus have largely centered on subunit vaccination against virion proteins but have yielded disappointing results. The advent of bacterial artificial chromosome technologies has enabled engineering of recombinant cytomegaloviruses (CMVs) from which virus genome-encoded immune modulation genes have been deleted, toward the goal of developing a safe and potentially more efficacious live attenuated vaccine. Here we report the findings of studies of such a vaccine against congenital CMV infection based on a virus with a targeted deletion in gp145, a virus genome-encoded inhibitor of protein kinase R, using the guinea pig model of vertical CMV transmission. The deletion virus was attenuated for dissemination in immunocompromised guinea pigs but elicited ELISA and neutralizing responses. The vaccine conferred protection against maternal DNAemia and congenital transmission and resulted in reduced viral loads in newborn guinea pigs. These results provide support for future studies of attenuated CMV vaccines.
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Genome architecture changes and major gene variations of Andrias davidianus ranavirus (ADRV). Vet Res 2013; 44:101. [PMID: 24143877 PMCID: PMC4015033 DOI: 10.1186/1297-9716-44-101] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 10/04/2013] [Indexed: 01/08/2023] Open
Abstract
Ranaviruses are emerging pathogens that have led to global impact and public concern. As a rarely endangered species and the largest amphibian in the world, the Chinese giant salamander, Andrias davidianus, has recently undergone outbreaks of epidemic diseases with high mortality. In this study, we isolated and identified a novel ranavirus from the Chinese giant salamanders that exhibited systemic hemorrhage and swelling syndrome with high death rate in China during May 2011 to August 2012. The isolate, designated Andrias davidianus ranavirus (ADRV), not only could induce cytopathic effects in different fish cell lines and yield high viral titers, but also caused severely hemorrhagic lesions and resulted in 100% mortality in experimental infections of salamanders. The complete genome of ADRV was sequenced and compared with other sequenced amphibian ranaviruses. Gene content and phylogenetic analyses revealed that ADRV should belong to an amphibian subgroup in genus Ranavirus, and is more closely related to frog ranaviruses than to other salamander ranaviruses. Homologous gene comparisons show that ADRV contains 99%, 97%, 94%, 93% and 85% homologues in RGV, FV3, CMTV, TFV and ATV genomes respectively. In addition, several variable major genes, such as duplicate US22 family-like genes, viral eukaryotic translation initiation factor 2 alpha gene and novel 75L gene with both motifs of nuclear localization signal (NLS) and nuclear export signal (NES), were predicted to contribute to pathogen virulence and host susceptibility. These findings confirm the etiologic role of ADRV in epidemic diseases of Chinese giant salamanders, and broaden our understanding of evolutionary emergence of ranaviruses.
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Bierle CJ, Semmens KM, Geballe AP. Double-stranded RNA binding by the human cytomegalovirus PKR antagonist TRS1. Virology 2013; 442:28-37. [PMID: 23601785 DOI: 10.1016/j.virol.2013.03.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 02/15/2013] [Accepted: 03/25/2013] [Indexed: 02/02/2023]
Abstract
Protein Kinase R (PKR) inhibits translation initiation following double-stranded RNA (dsRNA) binding and thereby represses viral replication. Human cytomegalovirus (HCMV) encodes two noncanonical dsRNA binding proteins, IRS1 and TRS1, and the expression of at least one of these PKR antagonists is essential for HCMV replication. In this study, we investigated the role of dsRNA binding by TRS1 in PKR inhibition. We found that purified TRS1 binds specifically to dsRNA with an affinity lower than that of PKR. Point mutants in the TRS1 dsRNA binding domain that were deficient in rescuing the replication of vaccinia virus lacking its PKR antagonist E3L were unable to bind to dsRNA but retained the ability bind to PKR. Thus TRS1 binding to dsRNA and to PKR are separable. Overall, our results are most consistent with a model in which TRS1 binds simultaneously to both dsRNA and PKR to inhibit PKR activation.
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Affiliation(s)
- Craig J Bierle
- Program in Molecular and Cellular Biology, University of Washington, Seattle, WA 98115, United States.
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