scholarly journals A Kinesin-3 Recruitment Complex Facilitates Axonal Sorting of Enveloped Alpha Herpesvirus Capsids

2019 ◽  
Author(s):  
Julian Scherer ◽  
Ian B. Hogue ◽  
Zachary A. Yaffe ◽  
Nikhila S. Tanneti ◽  
Benjamin Y. Winer ◽  
...  
Keyword(s):  
Herpes Simplex ◽  
Pseudorabies Virus ◽  
Human Herpes ◽  
Herpes Simplex Virus 1 ◽  
Viral Membrane ◽  
Simplex Virus ◽  
Spread Of Infection ◽  
Golgi Network ◽  
Motor Recruitment ◽  
Axonal Sorting

AbstractAxonal sorting, the controlled passage of specific cargoes from the cell soma into the axon compartment, is critical for establishing and maintaining the polarity of mature neurons. To delineate axonal sorting events, we took advantage of two neuroinvasive alpha-herpesviruses. Human herpes simplex virus 1 (HSV-1) and pseudorabies virus of swine (PRV; suid herpesvirus 1) have evolved as robust cargo of axonal sorting and transport mechanisms. For efficient axonal sorting and subsequent egress from axons and presynaptic termini, progeny capsids depend on three viral membrane proteins (Us7 (gI), Us8 (gE), and Us9), which engage axon-directed kinesin motors. We present evidence that Us7-9 of the veterinary pathogen pseudorabies virus (PRV) form a tripartite complex to recruit Kif1a, a kinesin-3 motor. Based on multi-channel super-resolution and live TIRF microscopy, complex formation and motor recruitment occurs at the trans-Golgi network. Subsequently, progeny virus particles enter axons as enveloped capsids in a transport vesicle. Artificial recruitment of Kif1a using a drug-inducible heterodimerization system was sufficient to rescue axonal sorting and anterograde spread of PRV mutants devoid of Us7-9. Importantly, biophysical evidence suggests that Us9 is able to increase the velocity of Kif1a, a previously undescribed phenomenon. In addition to elucidating mechanisms governing axonal sorting, our results provide further insight into the composition of neuronal transport systems used by alpha-herpesviruses, which will be critical for both inhibiting the spread of infection and the safety of herpesvirus-based oncolytic therapies.Author SummaryAlpha-herpesviruses represent a group of large, enveloped DNA viruses that are capable to establish a quiescent (also called latent) but reactivatable form of infection in the peripheral nervous system of their hosts. Following reactivation of latent genomes, virus progeny are formed in the soma of neuronal cells and depend on sorting into the axon for anterograde spread of infection to mucosal sites and potentially new host. We studied two alpha-herpesviruses (the veterinary pathogen pseudorabies virus (PRV) and human herpes simplex virus 1 (HSV-1)) and found viral membrane proteins Us7, Us8, and Us9 to form a complex, which is able to recruit kinsin-3 motors. Motor recruitment facilitates axonal sorting and subsequent transport to distal egress sites. Complex formation occurs at the trans-Golgi network and mediates efficiency of axonal sorting and motility characteristics of egressing capsids. We also used an artificial kinesin-3 recruitment system, which allows controlled induction of axonal sorting and transport for virus mutants lacking Us7, Us8, and Us9. Overall, these data contribute to our understanding of anterograde alpha-herpesvirus spread and kinesin-mediated sorting of vesicular axonal cargoes.

scholarly journals Herpes Simplex Virus Entry by a Nonconventional Endocytic Pathway

2020 ◽  
Vol 94 (24) ◽  
Author(s):  
Giulia Tebaldi ◽  
Suzanne M. Pritchard ◽  
Anthony V. Nicola
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Epithelial Cells ◽  
Retrograde Transport ◽  
Endocytic Pathway ◽  
Host Cells ◽  
Herpes Simplex Virus 1 ◽  
Simplex Virus ◽  
Golgi Network ◽  
Hsv 1

ABSTRACT Herpes simplex virus 1 (HSV-1) causes significant morbidity and mortality in humans worldwide. HSV-1 enters epithelial cells via an endocytosis mechanism that is low-pH dependent. However, the precise intracellular pathway has not been identified, including the compartment where fusion occurs. In this study, we utilized a combination of molecular and pharmacological approaches to better characterize HSV entry by endocytosis. HSV-1 entry was unaltered in both cells treated with small interfering RNA (siRNA) to Rab5 or Rab7 and cells expressing dominant negative forms of these GTPases, suggesting entry is independent of the conventional endo-lysosomal network. The fungal metabolite brefeldin A (BFA) and the quinoline compound Golgicide A (GCA) inhibited HSV-1 entry via beta-galactosidase reporter assay and impaired incoming virus transport to the nuclear periphery, suggesting a role for trans-Golgi network (TGN) functions and retrograde transport in HSV entry. Silencing of Rab9 or Rab11 GTPases, which are involved in the retrograde transport pathway, resulted in only a slight reduction in HSV infection. Together, these results suggest that HSV enters host cells by an intracellular route independent of the lysosome-terminal endocytic pathway. IMPORTANCE Herpes simplex virus 1 (HSV-1), the prototype alphaherpesvirus, is ubiquitous in the human population and causes lifelong infection that can be fatal in neonatal and immunocompromised individuals. HSV enters many cell types by endocytosis, including epithelial cells, the site of primary infection in the host. The intracellular itinerary for HSV entry remains unclear. We probed the potential involvement of several Rab GTPases in HSV-1 entry and suggest that endocytic entry of HSV-1 is independent of the canonical lysosome-terminal pathway. A nontraditional endocytic route may be employed, such as one that intersects with the trans-Golgi network (TGN). These results may lead to novel targets for intervention.

scholarly journals Cellular Cholesterol Facilitates the Postentry Replication Cycle of Herpes Simplex Virus 1

2017 ◽  
Vol 91 (14) ◽  
Author(s):  
George A. Wudiri ◽  
Anthony V. Nicola
Keyword(s):  
Herpes Simplex ◽  
Viral Genome ◽  
Herpes Simplex Virus 1 ◽  
Cellular Cholesterol ◽  
Viral Capsids ◽  
Simplex Virus ◽  
Spread Of Infection ◽  
Cell Spread ◽  
Replicative Cycle ◽  
Hsv 1

ABSTRACT Cholesterol is an essential component of cell membranes and is required for herpes simplex virus 1 (HSV-1) entry (1–3). Treatment of HSV-1-infected Vero cells with methyl beta-cyclodextrin from 2 to 9 h postentry reduced plaque numbers. Transport of incoming viral capsids to the nuclear periphery was unaffected by the cholesterol reduction, suggesting that cell cholesterol is important for the HSV-1 replicative cycle at a stage(s) beyond entry, after the arrival of capsids at the nucleus. The synthesis and release of infectious HSV-1 and cell-to-cell spread of infection were all impaired in cholesterol-reduced cells. Propagation of HSV-1 on DHCR24−/− fibroblasts, which lack the desmosterol-to-cholesterol conversion enzyme, resulted in the generation of infectious extracellular virions (HSVdes) that lack cholesterol and likely contain desmosterol. The specific infectivities (PFU per viral genome) of HSVchol and HSVdes were similar, suggesting cholesterol and desmosterol in the HSV envelope support similar levels of infectivity. However, infected DHCR24−/− fibroblasts released ∼1 log less infectious HSVdes and ∼1.5 log fewer particles than release of cholesterol-containing particles (HSVchol) from parental fibroblasts, suggesting that the hydrocarbon tail of cholesterol facilitates viral synthesis. Together, the results suggest multiple roles for cholesterol in the HSV-1 replicative cycle. IMPORTANCE HSV-1 infections are associated with a wide range of clinical manifestations that are of public health importance. Cholesterol is a key player in the complex interaction between viral and cellular factors that allows HSV-1 to enter host cells and establish infection. Previous reports have demonstrated a role for cellular cholesterol in the entry of HSV-1 into target cells. Here, we employed both chemical treatment and cells that were genetically defined to synthesize only desmosterol to demonstrate that cholesterol is important at stages following the initial entry and transport of viral capsids to the nucleus. Viral protein expression, encapsidation of the viral genome, and the release of mature virions were impacted by the reduction of cellular cholesterol. Cholesterol was also critical for cell-to-cell spread of infection. These findings provide new insights into the cholesterol dependence of HSV-1 replication.

scholarly journals The XPO6 Exportin Mediates Herpes Simplex Virus 1 gM Nuclear Release Late in Infection

2020 ◽  
Vol 94 (21) ◽  
Author(s):  
Hugo Boruchowicz ◽  
Josiane Hawkins ◽  
Kendra Cruz-Palomar ◽  
Roger Lippé
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Nuclear Membrane ◽  
Viral Protein ◽  
Herpes Simplex Virus 1 ◽  
Nuclear Membranes ◽  
Proteomics Approach ◽  
Simplex Virus ◽  
Golgi Network ◽  
Hsv 1

ABSTRACT The glycoprotein M of herpes simplex virus 1 (HSV-1) is dynamically relocated from nuclear membranes to the trans-Golgi network (TGN) during infection, but molecular partners that promote this relocalization are unknown. Furthermore, while the presence of the virus is essential for this phenomenon, it is not clear if this is facilitated by viral or host proteins. Past attempts to characterize glycoprotein M (gM) interacting partners identified the viral protein gN by coimmunoprecipitation and the host protein E-Syt1 through a proteomics approach. Interestingly, both proteins modulate the activity of gM on the viral fusion machinery. However, neither protein is targeted to the nuclear membrane and consequently unlikely explains the dynamic regulation of gM nuclear localization. We thus reasoned that gM may transiently interact with other molecules. To resolve this issue, we opted for a proximity-dependent biotin identification (BioID) proteomics approach by tagging gM with a BirA* biotinylation enzyme and purifying BirA substrates on a streptavidin column followed by mass spectrometry analysis. The data identified gM and 170 other proteins that specifically and reproducibly were labeled by tagged gM at 4 or 12 h postinfection. Surprisingly, 35% of these cellular proteins are implicated in protein transport. Upon testing select candidate proteins, we discovered that XPO6, an exportin, is required for gM to be released from the nucleus toward the TGN. This is the first indication of a host or viral protein that modulates the presence of HSV-1 gM on nuclear membranes. IMPORTANCE The mechanisms that enable integral proteins to be targeted to the inner nuclear membrane are poorly understood. Herpes simplex virus 1 (HSV-1) glycoprotein M (gM) is an interesting candidate, as it is dynamically relocalized from nuclear envelopes to the trans-Golgi network (TGN) in a virus- and time-dependent fashion. However, it was, until now, unclear how gM was directed to the nucleus or evaded that compartment later on. Through a proteomic study relying on a proximity-ligation assay, we identified several novel gM interacting partners, many of which are involved in vesicular transport. Analysis of select proteins revealed that XPO6 is required for gM to leave the nuclear membranes late in the infection. This was unexpected, as XPO6 is an exportin specifically associated with actin/profilin nuclear export. This raises some very interesting questions about the interaction of HSV-1 with the exportin machinery and the cargo specificity of XPO6.

scholarly journals Cellular Protein Kinase D Modulators Play a Role during Multiple Steps of Herpes Simplex Virus 1 Egress

2018 ◽  
Vol 92 (23) ◽  
Author(s):  
Élisabeth Roussel ◽  
Roger Lippé
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Protein Kinase ◽  
Cellular Protein ◽  
Host Protein ◽  
Protein Kinase D ◽  
Herpes Simplex Virus 1 ◽  
Nuclear Egress ◽  
Simplex Virus ◽  
Golgi Network

ABSTRACTThe assembly of new herpes simplex virus 1 (HSV-1) particles takes place in the nucleus. These particles then travel across the two nuclear membranes and acquire a final envelope from a cellular compartment. The contribution of the cell to the release of the virus is, however, little known. We previously demonstrated, using a synchronized infection, that the host protein kinase D and diacylglycerol, a lipid that recruits the kinase to thetrans-Golgi network (TGN), promote the release of the virus from that compartment. Given the role this cellular protein plays in the herpes simplex virus 1 life cycle and the many molecules that modulate its activity, we aimed to determine to what extent this virus utilizes the protein kinase D pathway during a nonsynchronized infection. Several molecular protein kinase D (PKD) regulators were targeted by RNA interference and viral production monitored. Surprisingly, many of these modulators negatively impacted the extracellular release of the virus. Overexpression studies, the use of pharmacological reagents, and assays to monitor intracellular lipids implicated in the biology of PKD suggested that these effects were oddly independent of total intracellular diacylglycerol levels. Instead, mapping of the viral intermediates by electron microscopy suggested that some of these modulators could regulate distinct steps along the viral egress pathway, notably nuclear egress. Altogether, this suggests a more complex contribution of PKD to HSV-1 egress than originally anticipated and new research avenues to explore.IMPORTANCEViruses are obligatory parasites that highjack numerous cellular functions. This is certainly true when it comes to transporting viral particles within the cell. Herpesviruses share the unique property of traveling through the two nuclear membranes by subsequent budding and fusion and acquiring their final envelope from a cellular organelle. Albeit disputed, the overall evidence from many laboratories points to thetrans-Golgi network (TGN) as the source of that membrane. Moreover, past findings revealed that the host protein kinase D (PKD) plays an important role at that stage, which is significant given the known implication of that protein in vesicular transport. The present findings suggest that the PKD machinery not only affects the late stages of herpes simplex virus I egress but also modulates earlier steps, such as nuclear egress. This opens up new means to control these viruses.

scholarly journals Functional Characterization of Glycoprotein H Chimeras Composed of Conserved Domains of the Pseudorabies Virus and Herpes Simplex Virus 1 Homologs

2015 ◽  
Vol 90 (1) ◽  
pp. 421-432 ◽  
Author(s):  
Sebastian W. Böhm ◽  
Marija Backovic ◽  
Barbara G. Klupp ◽  
Felix A. Rey ◽  
Thomas C. Mettenleiter ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Pseudorabies Virus ◽  
Herpes Simplex Virus 1 ◽  
Content Type ◽  
Functional Conservation ◽  
Glycoprotein H ◽  
Simplex Virus ◽  
Domain I ◽  
Hsv 1

ABSTRACTMembrane fusion is indispensable for entry of enveloped viruses into host cells. The conserved core fusion machinery of theHerpesviridaeconsists of glycoprotein B (gB) and the gH/gL complex. Recently, crystal structures of gH/gL of herpes simplex virus 2 (HSV-2) and Epstein-Barr virus and of a core fragment of pseudorabies virus (PrV) gH identified four structurally conserved gH domains. To investigate functional conservation, chimeric genes encoding combinations of individual domains of PrV and herpes simplex virus 1 (HSV-1) gH were expressed in rabbit kidney cells, and their processing and transport to the cell surface, as well as activity in fusion assays including gB, gD, and gL of PrV or HSV-1, were analyzed. Chimeric gH containing domain I of HSV-1 and domains II to IV of PrV exhibited limited fusion activity in the presence of PrV gB and gD and HSV-1 gL, but not of PrV gL. More strikingly, chimeric gH consisting of PrV domains I to III and HSV-1 domain IV exhibited considerable fusion activity together with PrV gB, gD, and gL. Replacing PrV gB with the HSV-1 protein significantly enhanced this activity. A cell line stably expressing this chimeric gH supported replication of gH-deleted PrV. Our results confirm the specificity of domain I for gL binding, demonstrate functional conservation of domain IV in two alphaherpesviruses from different genera, and indicate species-specific interactions of this domain with gB. They also suggest that gH domains II and III might form a structural and functional unit which does not tolerate major substitutions.IMPORTANCEEnvelope glycoprotein H (gH) is essential for herpesvirus-induced membrane fusion, which is required for host cell entry and viral spread. Although gH is structurally conserved within theHerpesviridae, its precise role and its interactions with other components of the viral fusion machinery are not fully understood. Chimeric proteins containing domains of gH proteins from different herpesviruses can serve as tools to elucidate the molecular basis of gH function. The present study shows that the C-terminal part of human herpesvirus 1 (herpes simplex virus 1) gH can functionally substitute for the corresponding part of suid herpesvirus 1 (pseudorabies virus) gH, whereas other tested combinations proved to be nonfunctional. Interestingly, the exchangeable fragment included the membrane-proximal end of the gH ectodomain (domain IV), which is most conserved in sequence and structure and might be capable of transient membrane interaction during fusion.

scholarly journals gD-Independent Superinfection Exclusion of Alphaherpesviruses

2016 ◽  
Vol 90 (8) ◽  
pp. 4049-4058 ◽  
Author(s):  
A. Criddle ◽  
T. Thornburg ◽  
I. Kochetkova ◽  
M. DePartee ◽  
M. P. Taylor
Keyword(s):  
Pseudorabies Virus ◽  
Fluorescent Protein ◽  
Viral Infections ◽  
Herpes Simplex Virus 1 ◽  
Viral Genomes ◽  
Superinfection Exclusion ◽  
Development Of Resistance ◽  
Simplex Virus ◽  
Spread Of Infection ◽  
Hsv 1

ABSTRACTMany viruses have the capacity to prevent a cell from being infected by a second virus, often termed superinfection exclusion. Alphaherpesviruses, including the human pathogen herpes simplex virus 1 (HSV-1) and the animal herpesvirus pseudorabies virus (PRV), encode a membrane-bound glycoprotein, gD, that can interfere with subsequent virion entry. We sought to characterize the timing and mechanism of superinfection exclusion during HSV-1 and PRV infection. To this end, we utilized recombinant viruses expressing fluorescent protein (FP) markers of infection that allowed the visualization of viral infections by microscopy and flow cytometry as well as the differentiation of viral progeny. Our results demonstrated the majority of HSV-1- and PRV-infected cells establish superinfection exclusion by 2 h postinfection. The modification of viral infections by virion inactivation and phosphonoacetic acid, cycloheximide, and actinomycin D treatments indicated new protein synthesis is needed to establish superinfection exclusion. Primary infection with gene deletion PRV recombinants identified that new gD expression is not required to establish superinfection exclusion of a secondary viral inoculum. We also identified the timing of coinfection events during axon-to-cell spread, with most occurring within a 2-h window, suggesting a role for cellular superinfection exclusion during neuroinvasive spread of infection. In summary, we have characterized a gD-independent mechanism of superinfection exclusion established by two members of the alphaherpesvirus family and identified a potential role of exclusion during the pathogenic spread of infection.IMPORTANCESuperinfection exclusion is a widely observed phenomenon initiated by a primary viral infection to prevent further viruses from infecting the same cell. The capacity for alphaherpesviruses to infect the same cell impacts rates of interviral recombination and disease. Interviral recombination allows genome diversification, facilitating the development of resistance to antiviral therapeutics and evasion of vaccine-mediated immune responses. Our results demonstrate superinfection exclusion occurs early, through a gD-independent process, and is important in the directed spread of infection. Identifying when and where in an infected host viral genomes are more likely to coinfect the same cell and generate viral recombinants will enhance the development of effective antiviral therapies and interventions.

scholarly journals The ESCRT-II Subunit EAP20/VPS25 and the Bro1 Domain Proteins HD-PTP and BROX Are Individually Dispensable for Herpes Simplex Virus 1 Replication

2019 ◽  
Vol 94 (4) ◽  
Author(s):  
Jenna Barnes ◽  
Duncan W. Wilson
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Pseudorabies Virus ◽  
Protein Sorting ◽  
Tyrosine Phosphatase ◽  
Herpes Simplex Virus 1 ◽  
Vacuolar Protein Sorting ◽  
Simplex Virus ◽  
Vacuolar Protein ◽  
Hsv 1

ABSTRACT Capsid envelopment during assembly of the neurotropic herpesviruses herpes simplex virus 1 (HSV-1) and pseudorabies virus (PRV) in the infected cell cytoplasm is thought to involve the late-acting cellular ESCRT (endosomal sorting complex required for transport) components ESCRT-III and VPS4 (vacuolar protein sorting 4). However, HSV-1, unlike members of many other families of enveloped viruses, does not appear to require the ESCRT-I subunit TSG101 or the Bro1 domain-containing protein ALIX (Alg-2-interacting protein X) to recruit and activate ESCRT-III. Alternative cellular factors that are known to be capable of regulating ESCRT-III function include the ESCRT-II complex and other members of the Bro1 family. We therefore used small interfering RNA (siRNA) to knock down the essential ESCRT-II subunit EAP20/VPS25 (ELL-associated protein 20/vacuolar protein sorting 25) and the Bro1 proteins HD-PTP (His domain-containing protein tyrosine phosphatase) and BROX (Bro1 domain and CAAX motif containing). We demonstrated reductions in levels of the targeted proteins by Western blotting and used quantitative microscopic assays to confirm loss of ESCRT-II and HD-PTP function. We found that in single-step replication experiments, the final yields of HSV-1 were unchanged following loss of EAP20, HD-PTP, or BROX. IMPORTANCE HSV-1 is a pathogen of the human nervous system that uses its own virus-encoded proteins and the normal cellular ESCRT machinery to drive the construction of its envelope. How HSV-1 structural proteins interact with ESCRT components and which subsets of cellular ESCRT proteins are utilized by the virus remain largely unknown. Here, we demonstrate that an essential component of the ESCRT-II complex and two ESCRT-associated Bro1 proteins are dispensable for HSV-1 replication.

scholarly journals Crystal Structure of the N-Terminal Half of the Traffic Controller UL37 from Herpes Simplex Virus 1

2017 ◽  
Vol 91 (20) ◽  
Author(s):  
Andrea L. Koenigsberg ◽  
Ekaterina E. Heldwein
Keyword(s):  
Crystal Structure ◽  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Pseudorabies Virus ◽  
Surface Region ◽  
Tegument Protein ◽  
Herpes Simplex Virus 1 ◽  
Tegument Proteins ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACT Inner tegument protein UL37 is conserved among all three subfamilies of herpesviruses. Studies of UL37 homologs from two alphaherpesviruses, herpes simplex virus 1 (HSV-1) and pseudorabies virus (PRV), have suggested that UL37 plays an essential albeit poorly defined role in intracellular capsid trafficking. At the same time, HSV and PRV homologs cannot be swapped, which suggests that in addition to a conserved function, UL37 homologs also have divergent virus-specific functions. Accurate dissection of UL37 functions requires detailed maps in the form of atomic-resolution structures. Previously, we reported the crystal structure of the N-terminal half of UL37 (UL37N) from PRV. Here, we report the crystal structure of HSV-1 UL37N. Comparison of the two structures reveals that UL37 homologs differ in their overall shapes, distributions of surface charges, and locations of projecting loops. In contrast, the previously identified R2 surface region is structurally conserved. We propose that within the N-terminal half of UL37, functional conservation is centered within the R2 surface region, whereas divergent structural elements pinpoint regions mediating virus-specific functions and may engage different binding partners. Together, the two structures can now serve as templates for a structure-guided exploration of both conserved and virus-specific functions of UL37. IMPORTANCE The ability to move efficiently within host cell cytoplasm is essential for replication in all viruses. It is especially important in the neuroinvasive alphaherpesviruses, such as human herpes simplex virus 1 (HSV-1), HSV-2, and veterinarian pseudorabies virus (PRV), that infect the peripheral nervous system and have to travel long distances along axons. Capsid movement in these viruses is controlled by capsid-associated tegument proteins, yet their specific roles have not yet been defined. Systematic exploration of the roles of tegument proteins in capsid trafficking requires detailed navigational charts in the form of their three-dimensional structures. Here, we determined the crystal structure of the N-terminal half of a conserved tegument protein, UL37, from HSV-1. This structure, along with our previously reported structure of the UL37 homolog from PRV, provides a much needed 3-dimensional template for the dissection of both conserved and virus-specific functions of UL37 in intracellular capsid trafficking.

scholarly journals Trimethylation of Histone H3 Lysine 4 by Set1 in the Lytic Infection of Human Herpes Simplex Virus 1

2006 ◽  
Vol 80 (12) ◽  
pp. 5740-5746 ◽  
Author(s):  
Jing Huang ◽  
Jennifer R. Kent ◽  
Brandon Placek ◽  
Kelly A. Whelan ◽  
Charles M. Hollow ◽  
...  
Keyword(s):  
Herpes Simplex ◽  
Histone H3 ◽  
Lytic Infection ◽  
Protein Methylation ◽  
Human Herpes ◽  
Herpes Simplex Virus 1 ◽  
Simplex Virus ◽  
Transcription And Replication ◽  
Hsv 1

ABSTRACT Human herpes simplex virus 1 (HSV-1) is a double-stranded DNA virus that causes facial, ocular, and encephalitic disease in humans. Previous work showed that the genome of HSV-1 is associated with acetylated and methylated histones during lytic infection. However, the physiological role of histone modifications in lytic infection of HSV-1 is unclear. We examined the role of protein methylation in lytic infection of HSV-1 using a protein methylation inhibitor, 5′-deoxy-5′-methylthioadenosine (MTA). We found that MTA strongly reduces the transcription and replication of HSV-1. Moreover, MTA treatment decreases the level of trimethylation of lysine 4 in histone H3 (H3K4me3) on the HSV-1 genome. These results suggest that protein methylation, and in particular, histone methylation, is involved in the lytic infection of HSV-1. To delineate the underlying mechanism, we investigated the role of two H3K4 methyltransferases, Set1 and Set7/9, in the lytic infection of HSV-1. Using small interference RNA, we found that the reduction of Set1, but not Set7/9, reduces the transcription and replication of HSV-1 and specifically decreases H3K4me3 on the virus genome. These results indicate that H3K4me3 mediated by Set1 is required for optimal gene expression and replication of HSV-1 during lytic infection and suggest that this pathway could be a potential point of pharmacological intervention during HSV-1 infection.

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