scholarly journals SAMHD1 Restricts Herpes Simplex Virus 1 in Macrophages by Limiting DNA Replication

2013 ◽  
Vol 87 (23) ◽  
pp. 12949-12956 ◽  
Author(s):  
Eui Tae Kim ◽  
Tommy E. White ◽  
Alberto Brandariz-Núñez ◽  
Felipe Diaz-Griffero ◽  
Matthew D. Weitzman

Macrophages play important roles in host immune defense against virus infection. During infection by herpes simplex virus 1 (HSV-1), macrophages acquire enhanced antiviral potential. Restriction of HSV-1 replication and progeny production is important to prevent viral spread, but the cellular mechanisms that inhibit the DNA virus in macrophages are unknown. SAMHD1 was recently identified as a retrovirus restriction factor highly expressed in macrophages. The SAMHD1 protein is expressed in both undifferentiated monocytes and differentiated macrophages, but retroviral restriction is limited to differentiated cells by modulation of SAMHD1 phosphorylation. It is proposed to block reverse transcription of retroviral RNA into DNA by depleting cellular deoxynucleotide triphosphates (dNTPs). Viruses with DNA genomes do not employ reverse transcription during infection, but replication of their viral genomes is also dependent on intracellular dNTP concentrations. Here, we demonstrate that SAMHD1 restricts replication of the HSV-1 DNA genome in differentiated macrophage cell lines. Depleting SAMHD1 in THP-1 cells enhanced HSV-1 replication, while ectopic overexpression of SAMHD1 in U937 cells repressed HSV-1 replication. SAMHD1 did not impact viral gene expression from incoming HSV-1 viral genomes. HSV-1 restriction involved the dNTP triphosphohydrolase activity of SAMHD1 and was partially overcome by addition of exogenous deoxynucleosides. Unlike retroviruses, restriction of HSV-1 was not affected by SAMHD1 phosphorylation status. Our results suggest that SAMHD1 functions broadly to inhibit replication of DNA viruses in nondividing macrophages.

2020 ◽  
Vol 94 (15) ◽  
Author(s):  
Tristan R. Grams ◽  
Terri G. Edwards ◽  
David C. Bloom

ABSTRACT Herpes simplex virus 1 (HSV-1) establishes a lifelong latent infection in peripheral nerve ganglia. Periodically, the virus reactivates from this latent reservoir and is transported to the original site of infection. Strains of HSV-1 have been noted to vary greatly in their virulence and reactivation efficiencies in animal models. While HSV-1 strain 17syn+ can be readily reactivated, strain KOS(M) shows little to no reactivation in the mouse and rabbit models of induced reactivation. Additionally, 17syn+ is markedly more virulent in vivo than KOS. This has raised questions regarding potential strain-specific differences in neuroinvasion and neurovirulence and their contribution to differences in the establishment of latency (or ability to spread back to the periphery) and to the reactivation phenotype. To determine if any difference in the ability to reactivate between strains 17syn+ and KOS(M) is manifest at the level of neurons, we utilized a recently characterized human neuronal cell line model of HSV latency and reactivation (LUHMES). We found that KOS(M) established latency with a higher number of viral genomes than strain 17syn+. Strikingly, we show that the KOS(M) viral genomes have a higher burden of heterochromatin marks than strain 17syn+. The increased heterochromatin profile for KOS(M) correlates with the reduced expression of viral lytic transcripts during latency and impaired induced reactivation compared to that of 17syn+. These results suggest that genomes entering neurons from HSV-1 infections with strain KOS(M) are more prone to rapid heterochromatinization than those of 17syn+ and that this results in a reduced ability to reactivate from latency. IMPORTANCE Herpes simplex virus 1 (HSV-1) establishes a lifelong infection in neuronal cells. The virus periodically reactivates and causes recurrent disease. Strains of HSV-1 vary greatly in their virulence and potential to reactivate in animal models. Although these differences are phenotypically well defined, factors contributing to the strains’ abilities to reactivate are largely unknown. We utilized a human neuronal cell line model of HSV latency and reactivation (LUHMES) to characterize the latent infection of two HSV-1 wild-type strains. We find that strain-specific differences in reactivation are recapitulated in LUHMES. Additionally, these differences correlate with the degree of heterochromatinization of the latent genomes. Our data suggest that the epigenetic state of the viral genome is an important determinant of reactivation that varies in a strain-specific manner. This work also shows the first evidence of strain-specific differences in reactivation outside the context of the whole animal at a human neuronal cell level.


2016 ◽  
Vol 90 (19) ◽  
pp. 8661-8672 ◽  
Author(s):  
Maitreyi Shivkumar ◽  
Clara Lawler ◽  
Ricardo Milho ◽  
Philip G. Stevenson

ABSTRACTHerpes simplex virus 1 (HSV-1) enters mice via olfactory epithelial cells and then colonizes the trigeminal ganglia (TG). Most TG nerve endings are subepithelial, so this colonization implies subepithelial viral spread, where myeloid cells provide an important line of defense. The outcome of infection of myeloid cells by HSV-1in vitrodepends on their differentiation state; the outcomein vivois unknown. Epithelial HSV-1 commonly infected myeloid cells, and Cre-Lox virus marking showed nose and lung infections passing through LysM-positive (LysM+) and CD11c+cells. In contrast, subcapsular sinus macrophages (SSMs) exposed to lymph-borne HSV-1 were permissive only when type I interferon (IFN-I) signaling was blocked; normally, their infection was suppressed. Thus, the outcome of myeloid cell infection helped to determine the HSV-1 distribution: subepithelial myeloid cells provided a route of spread from the olfactory epithelium to TG neurons, while SSMs blocked systemic spread.IMPORTANCEHerpes simplex virus 1 (HSV-1) infects most people and can cause severe disease. This reflects its persistence in nerve cells that connect to the mouth, nose, eye, and face. Established infection seems impossible to clear. Therefore, we must understand how it starts. This is difficult in humans, but mice show HSV-1 entry via the nose and then spread to its preferred nerve cells. We show that this spread proceeds in part via myeloid cells, which normally function in host defense. Myeloid infection was productive in some settings but was efficiently suppressed by interferon in others. Therefore, interferon acting on myeloid cells can stop HSV-1 spread, and enhancing this defense offers a way to improve infection control.


2019 ◽  
Vol 94 (4) ◽  
Author(s):  
José Antonio López-Guerrero ◽  
Carmen de la Nuez ◽  
Beatriz Praena ◽  
Enrique Sánchez-León ◽  
Claude Krummenacher ◽  
...  

ABSTRACT Myelin and lymphocyte protein (MAL) is a tetraspan integral membrane protein that resides in detergent-insoluble membrane fractions enriched in condensed membranes. MAL is expressed in oligodendrocytes, in Schwann cells, where it is essential for the stability of myelin, and at the apical membrane of epithelial cells, where it has a critical role in transport. In T lymphocytes, MAL is found at the immunological synapse and plays a crucial role in exosome secretion. However, no involvement of MAL in viral infections has been reported so far. Here, we show that herpes simplex virus 1 (HSV-1) virions travel in association with MAL-positive structures to reach the end of cellular processes, which contact uninfected oligodendrocytes. Importantly, the depletion of MAL led to a significant decrease in infection, with a drastic reduction in the number of lytic plaques in MAL-silenced cells. These results suggest a significant role for MAL in viral spread at cell contacts. The participation of MAL in the cell-to-cell spread of HSV-1 may shed light on the involvement of proteolipids in this process. IMPORTANCE Herpes simplex virus 1 (HSV-1) is a neurotropic pathogen that can infect many types of cells and establish latent infections in neurons. HSV-1 may spread from infected to uninfected cells by two main routes: by cell-free virus or by cell-to-cell spread. In the first case, virions exit into the extracellular space and then infect another cell from the outside. In the second case, viral transmission occurs through cell-to-cell contacts via a mechanism that is still poorly understood. A third mode of spread, using extracellular vesicles, also exists. In this study, we demonstrate the important role for a myelin protein, myelin and lymphocyte protein (MAL), in the process of cell-to-cell viral spread in oligodendrocytes. We show that MAL is involved in trafficking of virions along cell processes and that MAL depletion produces a significant alteration in the viral cycle, which reduces cell-to cell spread of HSV-1.


2014 ◽  
Vol 58 (12) ◽  
pp. 7451-7461 ◽  
Author(s):  
John E. Tavis ◽  
Hong Wang ◽  
Ann E. Tollefson ◽  
Baoling Ying ◽  
Maria Korom ◽  
...  

ABSTRACTHerpesviruses are large double-stranded DNA viruses that cause serious human diseases. Herpesvirus DNA replication depends on multiple processes typically catalyzed by nucleotidyltransferase superfamily (NTS) enzymes. Therefore, we investigated whether inhibitors of NTS enzymes would suppress replication of herpes simplex virus 1 (HSV-1) and HSV-2. Eight of 42 NTS inhibitors suppressed HSV-1 and/or HSV-2 replication by >10-fold at 5 μM, with suppression at 50 μM reaching ∼1 million-fold. Five compounds in two chemical families inhibited HSV replication in Vero and human foreskin fibroblast cells as well as the approved drug acyclovir did. The compounds had 50% effective concentration values as low as 0.22 μM with negligible cytotoxicity in the assays employed. The inhibitors suppressed accumulation of viral genomes and infectious particles and blocked events in the viral replication cycle before and during viral DNA replication. Acyclovir-resistant mutants of HSV-1 and HSV-2 remained highly sensitive to the NTS inhibitors. Five of six NTS inhibitors of the HSVs also blocked replication of another herpesvirus pathogen, human cytomegalovirus. Therefore, NTS enzyme inhibitors are promising candidates for new herpesvirus treatments that may have broad efficacy against members of the herpesvirus family.


2016 ◽  
Author(s):  
Shapira Lev ◽  
Ralph Maya ◽  
Tomer Enosh ◽  
Cohen Shai ◽  
Kobiler Oren

AbstractAlthough many viral particles can enter a single cell, the number of viral genomes per cell that establish infection is limited. However, mechanisms underlying this restriction were not explored in depth. For herpesviruses, one of the possible mechanisms suggested is chromatinization and silencing of the incoming genomes. To test this hypothesis, we followed infection with three herpes simplex virus 1 (HSV-1) fluorescence-expressing recombinants in the presence or absence of histone deacetylases inhibitors (HDACi’s). Unexpectedly, a lower number of viral genomes initiated expression in the presence of these inhibitors. This phenomenon was observed using several HDACi: Trichostatin A (TSA), Suberohydroxamic Acid (SBX), Valporic Acid (VPA) and Suberoylanilide Hydoxamic Acid (SAHA). We found that HDACi presence did not change the progeny outcome from the infected cells but did alter the kinetic of the infection. Different cell types (HFF, Vero and U2OS), which vary in their capability to activate intrinsic and innate immunity, show a cell specific basal average number of viral genomes establishing infection. Importantly, in all cell types, treatment with TSA reduced the number of viral genomes. ND10 nuclear bodies are known to interact with the incoming herpes genomes and repress viral replication. The viral immediate early protein, ICP0, is known to disassemble the ND10 bodies and to induce degradation of some of the host proteins in these domains. HDACi treated cells expressed higher levels of some of the host ND10 proteins (PML and ATRX), which may down regulate the number of viral genomes initiating expression per cell. Corroborating this hypothesis, infection with three HSV-1 recombinants carrying a deletion in the gene coding for ICP0, show a reduction in the number of genomes being expressed in U2OS cells. We suggest that alterations in the levels of host proteins involved in intrinsic antiviral defense may result in differences in the number of genomes that initiate expression.


2015 ◽  
Vol 89 (18) ◽  
pp. 9407-9416 ◽  
Author(s):  
Philipp Petermann ◽  
Elena Rahn ◽  
Katharina Thier ◽  
Mei-Ju Hsu ◽  
Frazer J. Rixon ◽  
...  

ABSTRACTThe cellular proteins nectin-1 and herpesvirus entry mediator (HVEM) can both mediate the entry of herpes simplex virus 1 (HSV-1). We have recently shown how these receptors contribute to infection of skin by investigating HSV-1 entry into murine epidermis.Ex vivoinfection studies reveal nectin-1 as the primary receptor in epidermis, whereas HVEM has a more limited role. Although the epidermis represents the outermost layer of skin, the contribution of nectin-1 and HVEM in the underlying dermis is still open. Here, we analyzed the role of each receptor during HSV-1 entry in murine dermal fibroblasts that were deficient in expression of either nectin-1 or HVEM or both receptors. Because infection was not prevented by the absence of either nectin-1 or HVEM, we conclude that they can act as alternative receptors. Although HVEM was found to be highly expressed on fibroblasts, entry was delayed in nectin-1-deficient cells, suggesting that nectin-1 acts as the more efficient receptor. In the absence of both receptors, entry was strongly delayed leading to a much reduced viral spread and virus production. These results suggest an unidentified cellular component that acts as alternate but inefficient receptor for HSV-1 on dermal fibroblasts. Characterization of the cellular entry mechanism suggests that HSV-1 can enter dermal fibroblasts both by direct fusion with the plasma membrane and via endocytic vesicles and that this is not dependent on the presence or absence of nectin-1. Entry was also shown to require dynamin and cholesterol, suggesting comparable entry pathways in keratinocytes and dermal fibroblasts.IMPORTANCEHerpes simplex virus (HSV) is a human pathogen which infects its host via mucosal surfaces or abraded skin. To understand how HSV-1 overcomes the protective barrier of mucosa or skin and reaches its receptors in tissue, it is essential to know which receptors contribute to the entry into individual skin cells. Previously, we have explored the contribution of nectin-1 and herpesvirus entry mediator (HVEM) as receptors for HSV-1 entry into murine epidermis, where keratinocytes form the major cell type. Since the underlying dermis consists primarily of fibroblasts, we have now extended our study of HSV-1 entry to dermal fibroblasts isolated from nectin-1- or HVEM-deficient mice or from mice deficient in both receptors. Our results demonstrate a role for both nectin-1 and HVEM as receptors and suggest a further receptor which appears much less efficient.


Author(s):  
Z. Hong Zhou ◽  
Jing He ◽  
Joanita Jakana ◽  
J. D. Tatman ◽  
Frazer J. Rixon ◽  
...  

Herpes simplex virus-1 (HSV-1) is a ubiquitous virus which is implicated in diseases ranging from self-curing cold sores to life-threatening infections. The 2500 Å diameter herpes virion is composed of a glycoprotein spike containing, lipid envelope, enclosing a protein layer (the tegument) in which is embedded the capsid (which contains the dsDNA genome). The B-, and A- and C-capsids, representing different morphogenetic stages in HSV-1 infected cells, are composed of 7, and 5 structural proteins respectively. The three capsid types are organized in similar T=16 icosahedral shells with 12 pentons, 150 hexons, and 320 connecting triplexes. Our previous 3D structure study at 26 Å revealed domain features of all these structural components and suggested probable locations for the outer shell proteins, VP5, VP26, VP19c and VP23. VP5 makes up most of both pentons and hexons. VP26 appeared to bind to the VP5 subunit in hexon but not to that in penton.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
David Shahnazaryan ◽  
Rana Khalil ◽  
Claire Wynne ◽  
Caroline A. Jefferies ◽  
Joan Ní Gabhann-Dromgoole ◽  
...  

AbstractHerpes simplex keratitis (HSK), caused by herpes simplex virus type 1 (HSV-1) infection, is the commonest cause of infectious blindness in the developed world. Following infection the virus is initially suspended in the tear film, where it encounters a multi-pronged immune response comprising enzymes, complement, immunoglobulins and crucially, a range of anti-viral and pro-inflammatory cytokines. However, given that HSV-1 can overcome innate immune responses to establish lifelong latency throughout a susceptible individual’s lifetime, there is significant interest in understanding the mechanisms employed by HSV-1 to downregulate the anti-viral type I interferon (IFN) mediated immune responses. This study aimed to investigate the interactions between infected cell protein (ICP)0 and key elements of the IFN pathway to identify possible novel targets that contribute to viral immune evasion. Reporter gene assays demonstrated the ability of ICP0 to inhibit type I IFN activity downstream of pathogen recognition receptors (PRRs) which are known to be involved in host antiviral defences. Further experiments identified interferon regulatory factor (IRF)7, a driver of type I IFN, as a potential target for ICP0. These findings increase our understanding of the pathogenesis of HSK and suggest IRF7 as a potential therapeutic target.


Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 196
Author(s):  
Sara Artusi ◽  
Emanuela Ruggiero ◽  
Matteo Nadai ◽  
Beatrice Tosoni ◽  
Rosalba Perrone ◽  
...  

The herpes simplex virus 1 (HSV-1) genome is extremely rich in guanine tracts that fold into G-quadruplexes (G4s), nucleic acid secondary structures implicated in key biological functions. Viral G4s were visualized in HSV-1 infected cells, with massive virus cycle-dependent G4-formation peaking during viral DNA replication. Small molecules that specifically interact with G4s have been shown to inhibit HSV-1 DNA replication. We here investigated the antiviral activity of TMPyP4, a porphyrin known to interact with G4s. The analogue TMPyP2, with lower G4 affinity, was used as control. We showed by biophysical analysis that TMPyP4 interacts with HSV-1 G4s, and inhibits polymerase progression in vitro; in infected cells, it displayed good antiviral activity which, however, was independent of inhibition of virus DNA replication or entry. At low TMPyP4 concentration, the virus released by the cells was almost null, while inside the cell virus amounts were at control levels. TEM analysis showed that virus particles were trapped inside cytoplasmatic vesicles, which could not be ascribed to autophagy, as proven by RT-qPCR, western blot, and immunofluorescence analysis. Our data indicate a unique mechanism of action of TMPyP4 against HSV-1, and suggest the unprecedented involvement of currently unknown G4s in viral or antiviral cellular defense pathways.


2017 ◽  
Vol 91 (12) ◽  
Author(s):  
Fumio Maeda ◽  
Jun Arii ◽  
Yoshitaka Hirohata ◽  
Yuhei Maruzuru ◽  
Naoto Koyanagi ◽  
...  

ABSTRACT Upon herpes simplex virus 1 (HSV-1) infection, the CD98 heavy chain (CD98hc) is redistributed around the nuclear membrane (NM), where it promotes viral de-envelopment during the nuclear egress of nucleocapsids. In this study, we attempted to identify the factor(s) involved in CD98hc accumulation and demonstrated the following: (i) the null mutation of HSV-1 UL34 caused specific dispersion throughout the cytoplasm of CD98hc and the HSV-1 de-envelopment regulators, glycoproteins B and H (gB and gH); (ii) as observed with CD98hc, gB, and gH, wild-type HSV-1 infection caused redistribution of the endoplasmic reticulum (ER) markers calnexin and ERp57 around the NM, whereas the UL34-null mutation caused cytoplasmic dispersion of these markers; (iii) the ER markers colocalized efficiently with CD98hc, gB, and gH in the presence and absence of UL34 in HSV-1-infected cells; (iv) at the ultrastructural level, wild-type HSV-1 infection caused ER compression around the NM, whereas the UL34-null mutation caused cytoplasmic dispersion of the ER; and (v) the UL34-null mutation significantly decreased the colocalization efficiency of lamin protein markers of the NM with CD98hc and gB. Collectively, these results indicate that HSV-1 infection causes redistribution of the ER around the NM, with resulting accumulation of ER-associated CD98hc, gB, and gH around the NM and that UL34 is required for ER redistribution, as well as for efficient recruitment to the NM of the ER-associated de-envelopment factors. Our study suggests that HSV-1 induces remodeling of the global ER architecture for recruitment of regulators mediating viral nuclear egress to the NM. IMPORTANCE The ER is an important cellular organelle that exists as a complex network extending throughout the cytoplasm. Although viruses often remodel the ER to facilitate viral replication, information on the effects of herpesvirus infections on ER morphological integrity is limited. Here, we showed that HSV-1 infection led to compression of the global ER architecture around the NM, resulting in accumulation of ER-associated regulators associated with nuclear egress of HSV-1 nucleocapsids. We also identified HSV-1 UL34 as a viral factor that mediated ER remodeling. Furthermore, we demonstrated that UL34 was required for efficient targeting of these regulators to the NM. To our knowledge, this is the first report showing that a herpesvirus remodels ER global architecture. Our study also provides insight into the mechanism by which the regulators for HSV-1 nuclear egress are recruited to the NM, where this viral event occurs.


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