Molecular Biology of Human Cytomegalovirus

A special issue of Viruses (ISSN 1999-4915). This special issue belongs to the section "Human Virology and Viral Diseases".

Deadline for manuscript submissions: 20 December 2024 | Viewed by 12810

Special Issue Editor


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Guest Editor
Department of Pediatrics, Virginia Commonwealth University, Richmond, VA 23298, USA
Interests: cytomegalovirus; congenital infection; pathogenesis; vaccines; antibodies; antivirals; tropism; molecular biology; genetics

Special Issue Information

Dear Colleagues,

Human cytomegalovirus (HCMV) is one of the largest and most complex pathogenic human viruses that we know of, coding for a large number of viral proteins and RNAs involved in host cell manipulation. While several of these have been studied in depth, the majority remain uncharacterized. The advent of facile viral genetic methods, combined with advances in cell biology, cell culture techniques, and ‘omics’ technologies, has accelerated the pace at which HCMV replication, cell tropism, host interactions, and pathogenesis are being mechanistically elucidated at the molecular level. This Special Issue will focus on recent advances in understanding the molecular biology of HCMV and its interactions with the host. While the primary focus is on HCMV, studies utilizing other cytomegaloviruses are appropriate if they model and elucidate parallel phenomena in HCMV.

Prof. Dr. Michael McVoy
Guest Editor

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Keywords

  • cytomegalovirus
  • molecular biology
  • genetics
  • pathogenesis

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Published Papers (8 papers)

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Research

20 pages, 3823 KiB  
Article
The Autophagy Receptor SQSTM1/p62 Is a Restriction Factor of HCMV Infection
by Nadine Krämer, Uxía Gestal Mato, Steffi Krauter, Nicole Büscher, Ahmad Afifi, Lina Herhaus, Luise Florin, Bodo Plachter and Christine Zimmermann
Viruses 2024, 16(9), 1440; https://doi.org/10.3390/v16091440 - 10 Sep 2024
Abstract
(1) Background: Intrinsic defense mechanisms are pivotal host strategies to restrict viruses already at early stages of their infection. Here, we addressed the question of how the autophagy receptor sequestome 1 (SQSTM1/p62, hereafter referred to as p62) interferes with human cytomegalovirus [...] Read more.
(1) Background: Intrinsic defense mechanisms are pivotal host strategies to restrict viruses already at early stages of their infection. Here, we addressed the question of how the autophagy receptor sequestome 1 (SQSTM1/p62, hereafter referred to as p62) interferes with human cytomegalovirus (HCMV) infection. (2) Methods: CRISPR/Cas9-mediated genome editing, mass spectrometry and the expression of p62 phosphovariants from recombinant HCMVs were used to address the role of p62 during infection. (3) Results: The knockout of p62 resulted in an increased release of HCMV progeny. Mass spectrometry revealed an interaction of p62 with cellular proteins required for nucleocytoplasmic transport. Phosphoproteomics further revealed that p62 is hyperphosphorylated at position S272 in HCMV-infected cells. Phosphorylated p62 showed enhanced nuclear retention, which is concordant with enhanced interaction with viral proteins relevant for genome replication and nuclear capsid egress. This modification led to reduced HCMV progeny release compared to a non-phosphorylated version of p62. (4) Conclusions: p62 is a restriction factor for HCMV replication. The activity of the receptor appears to be regulated by phosphorylation at position S272, leading to enhanced nuclear localization, viral protein degradation and impaired progeny production. Full article
(This article belongs to the Special Issue Molecular Biology of Human Cytomegalovirus)
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13 pages, 4296 KiB  
Article
Human Cytomegalovirus Dysregulates Cellular Dual-Specificity Tyrosine Phosphorylation-Regulated Kinases and Sonic Hedgehog Pathway Proteins in Neural Astrocyte and Placental Models
by Ece Egilmezer, Stuart T. Hamilton, Glen Lauw, Jasmine Follett, Eric Sonntag, Martin Schütz, Manfred Marschall and William D. Rawlinson
Viruses 2024, 16(6), 918; https://doi.org/10.3390/v16060918 - 5 Jun 2024
Viewed by 699
Abstract
Human cytomegalovirus (CMV) infection is the leading non-genetic cause of congenital malformation in developed countries, causing significant fetal injury, and in some cases fetal death. The pathogenetic mechanisms through which this host-specific virus infects then damages both the placenta and the fetal brain [...] Read more.
Human cytomegalovirus (CMV) infection is the leading non-genetic cause of congenital malformation in developed countries, causing significant fetal injury, and in some cases fetal death. The pathogenetic mechanisms through which this host-specific virus infects then damages both the placenta and the fetal brain are currently ill-defined. We investigated the CMV modulation of key signaling pathway proteins for these organs including dual-specificity tyrosine phosphorylation-regulated kinases (DYRK) and Sonic Hedgehog (SHH) pathway proteins using human first trimester placental trophoblast (TEV-1) cells, primary human astrocyte (NHA) brain cells, and CMV-infected human placental tissue. Immunofluorescence demonstrated the accumulation and re-localization of SHH proteins in CMV-infected TEV-1 cells with Gli2, Ulk3, and Shh re-localizing to the CMV cytoplasmic virion assembly complex (VAC). In CMV-infected NHA cells, DYRK1A re-localized to the VAC and DYRK1B re-localized to the CMV nuclear replication compartments, and the SHH proteins re-localized with a similar pattern as was observed in TEV-1 cells. Western blot analysis in CMV-infected TEV-1 cells showed the upregulated expression of Rb, Ulk3, and Shh, but not Gli2. In CMV-infected NHA cells, there was an upregulation of DYRK1A, DYRK1B, Gli2, Rb, Ulk3, and Shh. These in vitro monoculture findings are consistent with patterns of protein upregulation and re-localization observed in naturally infected placental tissue and CMV-infected ex vivo placental explant histocultures. This study reveals CMV-induced changes in proteins critical for fetal development, and identifies new potential targets for CMV therapeutic development. Full article
(This article belongs to the Special Issue Molecular Biology of Human Cytomegalovirus)
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16 pages, 5599 KiB  
Article
Discovery of a Novel Antiviral Effect of the Restriction Factor SPOC1 against Human Cytomegalovirus
by Anna K. Kuderna, Anna Reichel, Julia Tillmanns, Maja Class, Myriam Scherer and Thomas Stamminger
Viruses 2024, 16(3), 363; https://doi.org/10.3390/v16030363 - 27 Feb 2024
Viewed by 1269
Abstract
The chromatin-remodeler SPOC1 (PHF13) is a transcriptional co-regulator and has been identified as a restriction factor against various viruses, including human cytomegalovirus (HCMV). For HCMV, SPOC1 was shown to block the onset of immediate-early (IE) gene expression under low multiplicities of infection (MOI). [...] Read more.
The chromatin-remodeler SPOC1 (PHF13) is a transcriptional co-regulator and has been identified as a restriction factor against various viruses, including human cytomegalovirus (HCMV). For HCMV, SPOC1 was shown to block the onset of immediate-early (IE) gene expression under low multiplicities of infection (MOI). Here, we demonstrate that SPOC1-mediated restriction of IE expression is neutralized by increasing viral titers. Interestingly, our study reveals that SPOC1 exerts an additional antiviral function beyond the IE phase of HCMV replication. Expression of SPOC1 under conditions of high MOI resulted in severely impaired viral DNA replication and viral particle release, which may be attributed to inefficient viral transcription. With the use of click chemistry, the localization of viral DNA was investigated at late time points after infection. Intriguingly, we detected a co-localization of SPOC1, RNA polymerase II S5P and polycomb repressor complex 2 (PRC2) components in close proximity to viral DNA in areas that are hypothesized to harbor viral transcription sites. We further identified the N-terminal domain of SPOC1 to be responsible for interaction with EZH2, a subunit of the PRC2 complex. With this study, we report a novel and potent antiviral function of SPOC1 against HCMV that is efficient even with unrestricted IE gene expression. Full article
(This article belongs to the Special Issue Molecular Biology of Human Cytomegalovirus)
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22 pages, 3201 KiB  
Article
IE1 of Human Cytomegalovirus Inhibits Necroptotic Cell Death via Direct and Indirect Modulation of the Necrosome Complex
by Anna Theresa Heusel, Sophie Rapp, Thomas Stamminger and Myriam Scherer
Viruses 2024, 16(2), 290; https://doi.org/10.3390/v16020290 - 13 Feb 2024
Cited by 3 | Viewed by 1476
Abstract
Programmed necrosis is an integral part of intrinsic immunity, serving to combat invading pathogens and restricting viral dissemination. The orchestration of necroptosis relies on a precise interplay within the necrosome complex, which consists of RIPK1, RIPK3 and MLKL. Human cytomegalovirus (HCMV) has been [...] Read more.
Programmed necrosis is an integral part of intrinsic immunity, serving to combat invading pathogens and restricting viral dissemination. The orchestration of necroptosis relies on a precise interplay within the necrosome complex, which consists of RIPK1, RIPK3 and MLKL. Human cytomegalovirus (HCMV) has been found to counteract the execution of necroptosis during infection. In this study, we identify the immediate-early 1 (IE1) protein as a key antagonist of necroptosis during HCMV infection. Infection data obtained in a necroptosis-sensitive cell culture system revealed a robust regulation of post-translational modifications (PTMs) of the necrosome complex as well as the importance of IE1 expression for an effective counteraction of necroptosis. Interaction analyses unveiled an association of IE1 and RIPK3, which occurs in an RHIM-domain independent manner. We propose that this interaction manipulates the PTMs of RIPK3 by promoting its ubiquitination. Furthermore, IE1 was found to exert an indirect activity by modulating the levels of MLKL via antagonizing its interferon-mediated upregulation. Overall, we claim that IE1 performs a broad modulation of innate immune signaling to impede the execution of necroptotic cell death, thereby generating a favorable environment for efficient viral replication. Full article
(This article belongs to the Special Issue Molecular Biology of Human Cytomegalovirus)
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13 pages, 2672 KiB  
Article
The Human Cytomegalovirus Latency-Associated Gene Product Latency Unique Natural Antigen Regulates Latent Gene Expression
by Emma Poole, Jonathan Lau, Ian Groves, Kate Roche, Eain Murphy, Maria Carlan da Silva, Matthew Reeves and John Sinclair
Viruses 2023, 15(9), 1875; https://doi.org/10.3390/v15091875 - 4 Sep 2023
Cited by 3 | Viewed by 1270
Abstract
Human cytomegalovirus (HCMV) infection can lead to either lytic or latent infection, which is dependent on the regulation of the viral major immediate early promoter (MIEP). Suppression of the MIEP is a pre-requisite for latency and is driven by repressive epigenetic modifications at [...] Read more.
Human cytomegalovirus (HCMV) infection can lead to either lytic or latent infection, which is dependent on the regulation of the viral major immediate early promoter (MIEP). Suppression of the MIEP is a pre-requisite for latency and is driven by repressive epigenetic modifications at the MIEP during latent infection. However, other viral genes are expressed during latency and this is correlated with activatory epigenetic modifications at latent gene promoters. Yet the molecular basis of the differential regulation of latent and lytic gene expression by epigenetics is unclear. LUNA, a latent viral transcript, has been suggested to be important for HCMV latency and has also been shown to be important for efficient reactivation likely through its known deSUMOylase activity. Intriguingly, we and others have also observed that LUNA enhances latency-associated expression of the viral UL138 gene. Here, we show that in the absence of LUNA, the expression of multiple latency-associated transcripts is reduced during latent infection, which is correlated with a lack of activatory marks at their promoters. Interestingly, we also show that LUNA interacts with the hematopoietic transcription factor GATA-2, which has previously been shown to bind to a number of latency-associated gene promoters, and that this interaction is dependent on the deSUMOylase domain of LUNA. Finally, we show that the deSUMOylase activity of LUNA is required for the establishment and/or maintenance of an open chromatin configuration around latency-associated gene promoters. As such, LUNA plays a key role in efficient latency-associated viral gene expression and carriage of viral genome during latent carriage. Full article
(This article belongs to the Special Issue Molecular Biology of Human Cytomegalovirus)
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13 pages, 3690 KiB  
Article
The RL13 Temperance Factor Represses Replication of the Highly Cell Culture-Adapted Towne Strain of Human Cytomegalovirus
by Amine Ourahmane, Laura Hertel and Michael A. McVoy
Viruses 2023, 15(4), 1023; https://doi.org/10.3390/v15041023 - 21 Apr 2023
Cited by 1 | Viewed by 1523
Abstract
Human cytomegalovirus (CMV) has evolved to replicate while causing minimal damage, maintain life-long latency, reactivate sub-clinically, and, in spite of robust host immunity, produce and shed infectious virus in order to transmit to new hosts. The CMV temperance factor RL13 may contribute to [...] Read more.
Human cytomegalovirus (CMV) has evolved to replicate while causing minimal damage, maintain life-long latency, reactivate sub-clinically, and, in spite of robust host immunity, produce and shed infectious virus in order to transmit to new hosts. The CMV temperance factor RL13 may contribute to this strategy of coexistence with the host by actively restricting viral replication and spread. Viruses with an intact RL13 gene grow slowly in cell culture, release little extracellular virus, and form small foci. By contrast, viruses carrying disruptive mutations in the RL13 gene form larger foci and release higher amounts of cell-free infectious virions. Such mutations invariably arise during cell culture passage of clinical isolates and are consistently found in highly adapted strains. The potential existence in such strains of other mutations with roles in mitigating RL13’s restrictive effects, however, has not been explored. To this end, a mutation that frame shifts the RL13 gene in the highly cell culture-adapted laboratory strain Towne was repaired, and a C-terminal FLAG epitope was added. Compared to the frame-shifted parental virus, viruses encoding wild-type or FLAG-tagged wild-type RL13 produced small foci and replicated poorly. Within six to ten cell culture passages, mutations emerged in RL13 that restored replication and focus size to those of the RL13-frame-shifted parental virus, implying that none of the numerous adaptive mutations acquired by strain Towne during more than 125 cell culture passages mitigate the temperance activity of RL13. Whilst RL13-FLAG expressed by passage zero stocks was localized exclusively within the virion assembly compartment, RL13-FLAG with a E208K substitution that emerged in one lineage was mostly dispersed into the cytoplasm, suggesting that localization to the virion assembly compartment is likely required for RL13 to exert its growth-restricting activities. Changes in localization also provided a convenient way to assess the emergence of RL13 mutations during serial passage, highlighting the usefulness of RL13-FLAG Towne variants for elucidating the mechanisms underlying RL13’s temperance functions. Full article
(This article belongs to the Special Issue Molecular Biology of Human Cytomegalovirus)
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17 pages, 9506 KiB  
Article
A Virus Genetic System to Analyze the Fusogenicity of Human Cytomegalovirus Glycoprotein B Variants
by Xuan Zhou, Giorgia Cimato, Yihua Zhou, Giada Frascaroli and Wolfram Brune
Viruses 2023, 15(4), 979; https://doi.org/10.3390/v15040979 - 16 Apr 2023
Cited by 2 | Viewed by 1906
Abstract
Viruses can induce the fusion of infected and neighboring cells, leading to the formation of syncytia. Cell–cell fusion is mediated by viral fusion proteins on the plasma membrane of infected cells that interact with cellular receptors on neighboring cells. Viruses use this mechanism [...] Read more.
Viruses can induce the fusion of infected and neighboring cells, leading to the formation of syncytia. Cell–cell fusion is mediated by viral fusion proteins on the plasma membrane of infected cells that interact with cellular receptors on neighboring cells. Viruses use this mechanism to spread rapidly to adjacent cells or escape host immunity. For some viruses, syncytium formation is a hallmark of infection and a known pathogenicity factor. For others, the role of syncytium formation in viral dissemination and pathogenicity remains poorly understood. Human cytomegalovirus (HCMV) is an important cause of morbidity and mortality in transplant patients and the leading cause of congenital infections. Clinical HCMV isolates have broad cell tropism but differ in their ability to induce cell–cell fusions, and little is known about the molecular determinants. We developed a system to analyze HCMV glycoprotein B (gB) variants in a defined genetic background. HCMV strains TB40/E and TR were used as vectors to compare the fusogenicity of six gB variants from congenitally infected fetuses with those from three laboratory strains. Five of them conferred the ability to induce the fusion of MRC-5 human embryonic lung fibroblasts to one or both backbone strains, as determined by a split GFP–luciferase reporter system. The same gB variants were not sufficient to induce syncytia in infected ARPE-19 epithelial cells, suggesting that additional factors are involved. The system described here allows a systematic comparison of the fusogenicity of viral envelope glycoproteins and may help to clarify whether fusion-promoting variants are associated with increased pathogenicity. Full article
(This article belongs to the Special Issue Molecular Biology of Human Cytomegalovirus)
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12 pages, 2232 KiB  
Article
Inhibition of Cytomegalovirus by Pentacta pygmaea Fucosylated Chondroitin Sulfate Depends on Its Molecular Weight
by Poonam Sharma, Rohini Dwivedi, Priya Ray, Jayanti Shukla, Vitor H. Pomin and Ritesh Tandon
Viruses 2023, 15(4), 859; https://doi.org/10.3390/v15040859 - 28 Mar 2023
Cited by 2 | Viewed by 1927
Abstract
Many viruses attach to host cells by first interacting with cell surface proteoglycans containing heparan sulfate (HS) glycosaminoglycan chains and then by engaging with specific receptor, resulting in virus entry. In this project, HS–virus interactions were targeted by a new fucosylated chondroitin sulfate [...] Read more.
Many viruses attach to host cells by first interacting with cell surface proteoglycans containing heparan sulfate (HS) glycosaminoglycan chains and then by engaging with specific receptor, resulting in virus entry. In this project, HS–virus interactions were targeted by a new fucosylated chondroitin sulfate from the sea cucumber Pentacta pygmaea (PpFucCS) in order to block human cytomegalovirus (HCMV) entry into cells. Human foreskin fibroblasts were infected with HCMV in the presence of PpFucCS and its low molecular weight (LMW) fractions and the virus yield at five days post-infection was assessed. The virus attachment and entry into the cells were visualized by labeling the purified virus particles with a self-quenching fluorophore octadecyl rhodamine B (R18). The native PpFucCS exhibited potent inhibitory activity against HCMV specifically blocking virus entry into the cell and the inhibitory activities of the LMW PpFucCS derivatives were proportional to their chain lengths. PpFucCS and the derived oligosaccharides did not exhibit any significant cytotoxicity; moreover, they protected the infected cells from virus-induced lytic cell death. In conclusion, PpFucCS inhibits the entry of HCMV into cells and the high MW of this carbohydrate is a key structural element to achieve the maximal anti-viral effect. This new marine sulfated glycan can be developed into a potential prophylactic and therapeutic antiviral agent against HCMV infection. Full article
(This article belongs to the Special Issue Molecular Biology of Human Cytomegalovirus)
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