scholarly journals The Latency-Associated Transcript Inhibits Apoptosis via Downregulation of Components of the Type I Interferon Pathway during Latent Herpes Simplex Virus 1 Ocular Infection

2019 ◽  
Vol 93 (10) ◽  
Author(s):  
Kati Tormanen ◽  
Sariah Allen ◽  
Kevin R. Mott ◽  
Homayon Ghiasi

ABSTRACTThe herpes simplex virus (HSV-1) latency-associated transcript (LAT) has been shown to inhibit apoptosis via inhibiting activation of proapoptotic caspases. However, the mechanism of LAT control of apoptosis is unclear, because LAT is not known to encode a functional protein, and the LAT transcript is found largely in the nucleus. We hypothesized that LAT inhibits apoptosis by regulating expression of genes that control apoptosis. Consequently, we sought to establish the molecular mechanism of antiapoptosis functions of LAT at a transcriptional level during latent HSV-1 ocular infection in mice. Our results suggest the following. (i) LAT likely inhibits apoptosis via upregulation of several components of the type I interferon (IFN) pathway. (ii) LAT does not inhibit apoptosis via the caspase cascade at a transcriptional level or via downregulating Toll-like receptors (TLRs). (iii) The mechanism of LAT antiapoptotic effect is distinct from that of the baculovirus inhibitor of apoptosis (cpIAP) because replacement of LAT with the cpIAP gene resulted in a different gene expression pattern than in either LAT+or LAT−viruses. (iv) Replacement of LAT with the cpIAP gene does not cause upregulation of CD8 or markers of T cell exhaustion despite their having similar levels of latency, further supporting that LAT and cpIAP function via distinct mechanisms.IMPORTANCEThe HSV-1 latency reactivation cycle is the cause of significant human pathology. The HSV-1 latency-associated transcript (LAT) functions by regulating latency and reactivation, in part by inhibiting apoptosis. However, the mechanism of this process is unknown. Here we show that LAT likely controls apoptosis via downregulation of several components in the JAK-STAT pathway. Furthermore, we provide evidence that immune exhaustion is not caused by the antiapoptotic activity of the LAT.

2019 ◽  
Vol 93 (23) ◽  
Author(s):  
Maxime Chapon ◽  
Kislay Parvatiyar ◽  
Saba Roghiyh Aliyari ◽  
Jeffrey S. Zhao ◽  
Genhong Cheng

ABSTRACT In spite of several decades of research focused on understanding the biology of human herpes simplex virus 1 (HSV-1), no tool has been developed to study its genome in a high-throughput fashion. Here, we describe the creation of a transposon insertion mutant library of the HSV-1 genome. Using this tool, we aimed to identify novel viral regulators of type I interferon (IFN-I). HSV-1 evades the host immune system by encoding viral proteins that inhibit the type I interferon response. Applying differential selective pressure, we identified the three strongest viral IFN-I regulators in HSV-1. We report that the viral polymerase processivity factor UL42 interacts with the host transcription factor IFN regulatory factor 3 (IRF-3), inhibiting its phosphorylation and downstream beta interferon (IFN-β) gene transcription. This study represents a proof of concept for the use of high-throughput screening of the HSV-1 genome in investigating viral biology and offers new targets both for antiviral therapy and for oncolytic vector design. IMPORTANCE This work is the first to report the use of a high-throughput mutagenesis method to study the genome of HSV-1. We report three novel viral proteins potentially involved in regulating the host type I interferon response. We describe a novel mechanism by which the viral protein UL42 is able to suppress the production of beta interferon. The tool we introduce in this study can be used to study the HSV-1 genome in great detail to better understand viral gene functions.


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.


2009 ◽  
Vol 83 (23) ◽  
pp. 12399-12406 ◽  
Author(s):  
Vineet D. Menachery ◽  
David A. Leib

ABSTRACT The type I interferon (IFN) cascade is critical in controlling viral replication and pathogenesis. Recognition pathways triggered by viral infection rapidly induce the type I IFN cascade, often in an IFN regulatory factor 3 (IRF-3)-dependent fashion. This dependence predicts that loss of IRF-3 would render early recognition pathways inoperative and thereby impact virus replication, but this has not been observed previously with herpes simplex virus type 1 (HSV-1) in vitro. In this study, HSV-1-infected IRF-3−/− bone marrow-derived dendritic cells (BMDCs) and macrophages supported increased HSV replication compared to control cells. In addition, IRF-3-deficient BMDCs exhibited delayed type I IFN synthesis compared to control cells. However, while IFN pretreatment of IRF-3−/− BMDCs resulted in reduced virus titers, a far greater reduction was seen after IFN treatment of wild-type cells. This suggests that even in the presence of exogenously supplied IFN, IRF-3−/− BMDCs are inherently defective in the control of HSV-1 replication. Together, these results demonstrate a critical role for IRF-3-mediated pathways in controlling HSV-1 replication in cells of the murine immune system.


Virology ◽  
2008 ◽  
Vol 374 (2) ◽  
pp. 487-494 ◽  
Author(s):  
Karen E. Johnson ◽  
Byeongwoon Song ◽  
David M. Knipe

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Longzhen He ◽  
Baocheng Wang ◽  
Yuanyuan Li ◽  
Leqing Zhu ◽  
Peiling Li ◽  
...  

The innate immune response is the first line defense against viral infections. Novel genes involved in this system are continuing to emerge. SLC15A3, a proton-coupled histidine and di-tripeptide transporter that was previously found in lysosomes, has been reported to inhibit chikungunya viral replication in host cells. In this study, we found that SLC15A3 was significantly induced by DNA virus herpes simplex virus-1(HSV-1) in monocytes from human peripheral blood mononuclear cells. Aside from monocytes, it can also be induced by HSV-1 in 293T, HeLa cells, and HaCaT cells. Overexpression of SLC15A3 in 293T cells inhibits HSV-1 replication and enhances type I and type III interferon (IFN) responses, while silencing SLC15A3 leads to enhanced HSV-1 replication with reduced IFN production. Moreover, we found that SLC15A3 interacted with MAVS and STING and potentiated MAVS- and STING-mediated IFN production. These results demonstrate that SLC15A3 participates in anti-HSV-1 innate immune responses by regulating MAVS- and STING-mediated signaling pathways.


2006 ◽  
Vol 87 (3) ◽  
pp. 489-499 ◽  
Author(s):  
Daniel J. J. Carr ◽  
John Ash ◽  
Thomas E. Lane ◽  
William A. Kuziel

Ocular herpes simplex virus type 1 (HSV-1) infection elicits a strong inflammatory response that is associated with production of the β chemokines CCL3 and CCL5, which share a common receptor, CCR5. To gain insight into the role of these molecules in ocular immune responses, the corneas of wild-type (WT) and CCR5-deficient (CCR5−/−) mice were infected with HSV-1 and inflammatory parameters were measured. In the absence of CCR5, the early infiltration of neutrophils into the cornea was diminished. Associated with this aberrant leukocyte recruitment, neutrophils in CCR5−/− mice were restricted to the stroma, whereas in WT mice, these cells trafficked to the stroma and epithelial layers of the infected cornea. Virus titres and cytokine/chemokine levels in the infected tissue of these mice were similar for the first 5 days after infection. However, by day 7 post-infection, the CCR5−/− mice showed a significant elevation in the chemokines CCL2, CCL5, CXCL9 and CXCL10 in the trigeminal ganglion and brainstem, as well as a significant increase in virus burden. The increase in chemokine expression was associated with an increase in the infiltration of CD4 and/or CD8 T cells into the trigeminal ganglion and brainstem of CCR5−/− mice. Surprisingly, even though infected CCR5−/− mice were less efficient at controlling the progression of virus replication, there was no difference in mortality. These results suggest that, although CCR5 plays a role in regulating leukocyte trafficking and control of virus burden, compensatory mechanisms are involved in preventing mortality following HSV-1 infection.


2001 ◽  
Vol 75 (20) ◽  
pp. 9596-9600 ◽  
Author(s):  
Sabine Vollstedt ◽  
Marco Franchini ◽  
Gottfried Alber ◽  
Mathias Ackermann ◽  
Mark Suter

ABSTRACT Interferon (IFN) type I (alpha/beta IFN [IFN-α/β]) is very important in directly controlling herpes simplex virus type I (HSV-1) replication as well as in guiding and upregulating specific immunity against this virus. By contrast, the roles of IFN type II (IFN-γ) and antibodies in the defense against HSV-1 are not clear. Mice without a functional IFN system and no mature B and T cells (AGR mice) did not survive HSV-1 infection in the presence or absence of neutralizing antibodies to the virus. Mice without a functional IFN type I system and with no mature B and T cells (AR129 mice) were unable to control infection with as little as 10 PFU of HSV-1 strain F. By contrast, in the presence of passively administered neutralizing murine antibodies to HSV-1, some AR129 mice survived infection with up to104PFU of HSV-1. This acute immune response was dependent on the presence of interleukin-12 (IL-12) p75. Interestingly, some virus-infected mice stayed healthy for several months, at which time antibody to HSV-1 was no longer detectable. Treatment of these virus-exposed mice with dexamethasone led to death in approximately 40% of the mice. HSV-1 was found in brains of mice that did not survive dexamethasone treatment, whereas HSV-1 was absent in those that survived the treatment. We conclude that in the presence of passively administered HSV-1-specific antibodies, the IL-12-induced IFN-γ-dependent innate immune response is able to control low doses of virus infection. Surprisingly, in a significant proportion of these mice, HSV-1 appears to persist in the absence of antibodies and specific immunity.


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.


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