Herpes simplex virus-1 infects the olfactory bulb shortly following ocular infection and exhibits a long-term inflammatory profile in the form of effector and HSV-1-specific T cells

ABSTRACT Dok-1 and Dok-2 negatively regulate responses downstream of several immune receptors in lymphoid and myeloid cells. Recent evidence showed that Dok proteins are essential in the formation of memory CD8+ T cells to an exogenous epitope expressed by vaccinia virus; however, the importance of Dok-1 and Dok-2 in the control of viral infection is unknown. Here, we investigated the role of Dok proteins in modulating the immune response against herpes simplex virus 1 (HSV-1) in a mouse model of ocular infection. During acute infection, viral titers in the eye were similar in wild-type (WT) and Dok-1 and Dok-2 double-knockout (DKO) mice, and the percentages of infiltrating leukocytes were similar in DKO and WT corneas and trigeminal ganglia (TG). DKO mice exhibited a diminished CD8+ T cell response to the immunodominant HSV-1 glycoprotein B (gB) epitope in the spleen and draining lymph nodes compared to WT mice during acute infection. Remarkably, gB-specific CD8+ T cells almost completely disappeared in the spleens of DKO mice during latency, and the reduction of CD8+ effector memory T (Tem) cells was more severe than that of CD8+ central memory T (Tcm) cells. The percentage of gB-specific CD8+ T cells in TG during latency was also dramatically reduced in DKO mice; however, they were phenotypically similar to those from WT mice. In ex vivo assays, reactivation was detected earlier in TG cultures from infected DKO versus WT mice. Thus, Dok-1 and Dok-2 promote survival of gB-specific CD8+ T cells in TG latently infected with HSV-1. IMPORTANCE HSV-1 establishes lifelong latency in sensory neurons of trigeminal ganglia (TG). In humans, HSV-1 is able to sporadically reactivate from latently infected neurons and establish a lytic infection at a site to which the neurons project. Most herpetic disease in humans is due to reactivation of HSV-1 from latency rather than to primary acute infection. CD8+ T cells are thought to play an important role in controlling recurrent infections. In this study, we examined the involvement of Dok-1 and Dok-2 signaling proteins in the control of HSV-1 infection. We provide evidence that Dok proteins are required to maintain a CD8+ T cell response against HSV-1 during latency—especially CD8+ Tem cells—and that they negatively affect HSV-1 reactivation from latency. Elucidating Dok-mediated mechanisms involved in the control of HSV-1 reactivation from latency might contribute to the development of therapeutic strategies to prevent recurrent HSV-1-induced pathology.

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Latent Herpes Simplex Virus 1 Infection Does Not Induce Apoptosis in Human Trigeminal Ganglia

Journal of Virology ◽

10.1128/jvi.03481-14 ◽

2015 ◽

Vol 89 (10) ◽

pp. 5747-5750 ◽

Cited By ~ 2

Author(s):

Susanne Himmelein ◽

Anja Lindemann ◽

Inga Sinicina ◽

Michael Strupp ◽

Thomas Brandt ◽

...

Keyword(s):

T Cells ◽

Herpes Simplex Virus ◽

Herpes Simplex ◽

Caspase 3 ◽

Trigeminal Ganglia ◽

Herpes Simplex Virus 1 ◽

Reverse Transcription Quantitative Pcr ◽

Latently Infected ◽

Simplex Virus ◽

Hsv 1

Herpes simplex virus 1 (HSV-1) can establish lifelong latency in human trigeminal ganglia. Latently infected ganglia contain CD8+T cells, which secrete granzyme B and are thus capable of inducing neuronal apoptosis. Using immunohistochemistry and single-cell reverse transcription-quantitative PCR (RT-qPCR), higher frequency and transcript levels of caspase-3 were found in HSV-1-negative compared to HSV-1-positive ganglia and neurons, respectively. No terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) assay-positive neurons were detected. The infiltrating T cells do not induce apoptosis in latently infected neurons.

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Herpes Simplex Virus 1 Reactivates from Autonomic Ciliary Ganglia Independently from Sensory Trigeminal Ganglia To Cause Recurrent Ocular Disease

Journal of Virology ◽

10.1128/jvi.00468-15 ◽

2015 ◽

Vol 89 (16) ◽

pp. 8383-8391 ◽

Cited By ~ 20

Author(s):

Sungseok Lee ◽

Angela M. Ives ◽

Andrea S. Bertke

Keyword(s):

Herpes Simplex Virus ◽

Herpes Simplex ◽

Recurrent Disease ◽

Clinical Disease ◽

Ocular Infection ◽

Sensory Ganglia ◽

Autonomic Ganglia ◽

Herpes Simplex Virus 1 ◽

Simplex Virus ◽

Hsv 1

ABSTRACTHerpes simplex virus 1 (HSV-1) and HSV-2 establish latency in sensory and autonomic neurons after ocular or genital infection, but their recurrence patterns differ. HSV-1 reactivates from latency to cause recurrent orofacial disease, and while HSV-1 also causes genital lesions, HSV-2 recurs more efficiently in the genital region and rarely causes ocular disease. The mechanisms regulating these anatomical preferences are unclear. To determine whether differences in latent infection and reactivation in autonomic ganglia contribute to differences in HSV-1 and HSV-2 anatomical preferences for recurrent disease, we compared HSV-1 and HSV-2 clinical disease, acute and latent viral loads, and viral gene expression in sensory trigeminal and autonomic superior cervical and ciliary ganglia in a guinea pig ocular infection model. HSV-2 produced more severe acute disease, correlating with higher viral DNA loads in sensory and autonomic ganglia, as well as higher levels of thymidine kinase expression, a marker of productive infection, in autonomic ganglia. HSV-1 reactivated in ciliary ganglia, independently from trigeminal ganglia, to cause more frequent recurrent symptoms, while HSV-2 replicated simultaneously in autonomic and sensory ganglia to cause more persistent disease. While both HSV-1 and HSV-2 expressed the latency-associated transcript (LAT) in the trigeminal and superior cervical ganglia, only HSV-1 expressed LAT in ciliary ganglia, suggesting that HSV-2 is not reactivation competent or does not fully establish latency in ciliary ganglia. Thus, differences in replication and viral gene expression in autonomic ganglia may contribute to differences in HSV-1 and HSV-2 acute and recurrent clinical disease.IMPORTANCEHerpes simplex virus 1 (HSV-1) and HSV-2 establish latent infections, from which the viruses reactivate to cause recurrent disease throughout the life of the host. However, the viruses exhibit different manifestations and frequencies of recurrent disease. HSV-1 and HSV-2 establish latency in both sensory and autonomic ganglia. Autonomic ganglia are more responsive than sensory ganglia to stimuli associated with recurrent disease in humans, such as stress and hormone fluctuations, suggesting that autonomic ganglia may play an important role in recurrent disease. We show that HSV-1 can reactivate from autonomic ganglia, independently from sensory ganglia, to cause recurrent ocular disease. We found no evidence that HSV-2 could reactivate from autonomic ganglia independently from sensory ganglia after ocular infection, but HSV-2 did replicate in both ganglia simultaneously to cause persistent disease. Thus, viral replication and reactivation in autonomic ganglia contribute to different clinical disease manifestations of HSV-1 and HSV-2 after ocular infection.

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The CCCTC Binding Factor, CTRL2, Modulates Heterochromatin Deposition and the Establishment of Herpes Simplex Virus 1 Latency In Vivo

Journal of Virology ◽

10.1128/jvi.00415-19 ◽

2019 ◽

Vol 93 (13) ◽

Cited By ~ 2

Author(s):

Shannan D. Washington ◽

Pankaj Singh ◽

Richard N. Johns ◽

Terri G. Edwards ◽

Michael Mariani ◽

...

Keyword(s):

Gene Expression ◽

Herpes Simplex Virus ◽

Herpes Simplex ◽

Transcriptional Control ◽

Neuronal Cell ◽

Ocular Infection ◽

Herpes Simplex Virus 1 ◽

Lytic Gene ◽

Simplex Virus ◽

Hsv 1

ABSTRACT The cellular insulator protein CTCF plays a role in herpes simplex virus 1 (HSV-1) latency through the establishment and regulation of chromatin boundaries. We previously found that the CTRL2 regulatory element downstream from the latency-associated transcript (LAT) enhancer was bound by CTCF during latency and underwent CTCF eviction at early times postreactivation in mice latently infected with 17syn+ virus. We also showed that CTRL2 was a functional enhancer-blocking insulator in both epithelial and neuronal cell lines. We hypothesized that CTRL2 played a direct role in silencing lytic gene expression during the establishment of HSV-1 latency. To test this hypothesis, we used a recombinant virus with a 135-bp deletion spanning only the core CTRL2 insulator domain (ΔCTRL2) in the 17syn+ background. Deletion of CTRL2 resulted in restricted viral replication in epithelial cells but not neuronal cells. Following ocular infection, mouse survival decreased in the ΔCTRL2-infected cohort, and we found a significant decrease in the number of viral genomes in mouse trigeminal ganglia (TG) infected with ΔCTRL2, indicating that the CTRL2 insulator was required for the efficient establishment of latency. Immediate early (IE) gene expression significantly increased in the number of ganglia infected with ΔCTRL2 by 31 days postinfection relative to the level with 17syn+ infection, indicating that deletion of the CTRL2 insulator disrupted the organization of chromatin domains during HSV-1 latency. Finally, chromatin immunoprecipitation with high-throughput sequencing (ChIP-seq) analyses of TG from ΔCTRL2-infected mice confirmed that the distribution of the repressive H3K27me3 (histone H3 trimethylated at K27) mark on the ΔCTRL2 recombinant genomes was altered compared to that of the wild type, indicating that the CTRL2 site modulates the repression of IE genes during latency. IMPORTANCE It is becoming increasingly clear that chromatin insulators play a key role in the transcriptional control of DNA viruses. The gammaherpesviruses Epstein-Barr virus (EBV) and Kaposi’s sarcoma-associated herpesvirus (KSHV) utilize chromatin insulators to order protein recruitment and dictate the formation of three-dimensional DNA loops that spatially control transcription and latency. The contribution of chromatin insulators in alphaherpesvirus transcriptional control is less well understood. The work presented here begins to bridge that gap in knowledge by showing how one insulator site in HSV-1 modulates lytic gene transcription and heterochromatin deposition as the HSV-1 genome establishes latency.

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Herpes Simplex Virus 1-Specific CD8+ T Cell Priming and Latent Ganglionic Retention Are Shaped by Viral Epitope Promoter Kinetics

Journal of Virology ◽

10.1128/jvi.01193-19 ◽

2019 ◽

Vol 94 (5) ◽

Author(s):

Benjamin R. Treat ◽

Sarah M. Bidula ◽

Anthony J. St. Leger ◽

Robert L. Hendricks ◽

Paul R. Kinchington

Keyword(s):

T Cells ◽

Herpes Simplex ◽

T Cell ◽

Viral Proteins ◽

Cell Populations ◽

Herpes Simplex Virus 1 ◽

Viral Promoters ◽

Simplex Virus ◽

Hsv 1

ABSTRACT Reactivation of herpes simplex virus 1 (HSV-1) from neurons in sensory ganglia such as the trigeminal ganglia (TG) is influenced by virus-specific CD8+ T cells that infiltrate the ganglia at the onset of latency and contract to a stable activated tissue-resident memory population. In C57BL/6 mice, half of HSV-specific CD8+ T cells (gB-CD8s) recognize one dominant epitope (residues 498 to 505) on glycoprotein B (gB498–505), while the remainder (non-gB-CD8s) recognize 19 subdominant epitopes from 12 viral proteins. To address how expression by HSV-1 influences the formation and ganglionic retention of CD8+ T cell populations, we developed recombinant HSV-1 with the native immunodominant gB epitope disrupted but then expressed ectopically from different viral promoters. In mice, the epitope expressed from the gB promoter restored full gB-CD8 immunodominance to 50%. Intriguingly, earlier expression from constitutive, immediate-early, and early promoters did not significantly increase immunodominance, indicating that these promoters cannot elicit more than half of the CD8 compartment. Epitope expressed from candidate viral promoters of “true late” HSV-1 genes either delayed or reduced the priming efficiency of gB-CD8s and their levels in the TG at early times. HSV expressing the epitope from the full latency-associated transcript promoter did not efficiently prime gB-CD8s; however, gB-CD8s primed by a concurrent wild-type flank infection infiltrated the TG and were retained long term, suggesting that latent epitope expression is sufficient to retain gB-CD8s. Taken together, the data indicate that viral promoters shape latent HSV-1-specific CD8+ T cell populations and should be an important consideration in future vaccine design. IMPORTANCE Latency of HSV-1 in host neurons enables long-term persistence from which reactivation may occur to cause recurrent diseases, such as blinding herpetic stromal keratitis. Latency is not antigenically silent, and viral proteins are sporadically expressed at low levels without full virion production. This protein expression is recognized by ganglion-resident HSV-1-specific CD8+ T cells that maintain a protective resident population. Since these T cells can influence lytic/latent decisions in reactivating neurons, we argue that improving their ganglionic retention and function may offer a strategy in vaccine design to reduce reactivation and recurrent disease. To understand factors driving the infiltration and retention of ganglionic CD8s, we examined several HSV recombinants that have different viral promoters driving expression of the immunodominant gB epitope. We show that the selection of epitope promoter influences CD8+ T cell population hierarchies and their function.

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Microglia Reduce Herpes Simplex Virus 1 Lethality of Mice with Decreased T Cell and Interferon Responses in Brains

International Journal of Molecular Sciences ◽

10.3390/ijms222212457 ◽

2021 ◽

Vol 22 (22) ◽

pp. 12457

Author(s):

Meng-Shan Tsai ◽

Li-Chiu Wang ◽

Hsien-Yang Tsai ◽

Yu-Jheng Lin ◽

Hua-Lin Wu ◽

...

Keyword(s):

T Cells ◽

Herpes Simplex Virus ◽

Herpes Simplex ◽

Infection Model ◽

Virus Infectivity ◽

Herpes Simplex Virus 1 ◽

Viral Loads ◽

Simplex Virus ◽

Hsv 1

Herpes simplex virus 1 (HSV-1) infects the majority of the human population and can induce encephalitis, which is the most common cause of sporadic, fatal encephalitis. An increase of microglia is detected in the brains of encephalitis patients. The issues regarding whether and how microglia protect the host and neurons from HSV-1 infection remain elusive. Using a murine infection model, we showed that HSV-1 infection on corneas increased the number of microglia to outnumber those of infiltrating leukocytes (macrophages, neutrophils, and T cells) and enhanced microglia activation in brains. HSV-1 antigens were detected in brain neurons, which were surrounded by microglia. Microglia depletion increased HSV-1 lethality of mice with elevated brain levels of viral loads, infected neurons, neuron loss, CD4 T cells, CD8 T cells, neutrophils, interferon (IFN)-β, and IFN-γ. In vitro studies demonstrated that microglia from infected mice reduced virus infectivity. Moreover, microglia induced IFN-β and the signaling pathway of signal transducer and activator of transcription (STAT) 1 to inhibit viral replication and damage of neurons. Our study reveals how microglia protect the host and neurons from HSV-1 infection.

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CD8+T Cells Play a Bystander Role in Mice Latently Infected with Herpes Simplex Virus 1

Journal of Virology ◽

10.1128/jvi.00255-16 ◽

2016 ◽

Vol 90 (10) ◽

pp. 5059-5067 ◽

Cited By ~ 18

Author(s):

Kevin R. Mott ◽

David Gate ◽

Harry H. Matundan ◽

Yasamin N. Ghiasi ◽

Terrence Town ◽

...

Keyword(s):

T Cells ◽

Herpes Simplex Virus ◽

Herpes Simplex ◽

Trigeminal Ganglia ◽

Wild Type ◽

Herpes Simplex Virus 1 ◽

Link Type ◽

Latently Infected ◽

Simplex Virus ◽

Hsv 1

ABSTRACTBased on an explant reactivation model, it has been proposed that CD8+T cells maintain latency in trigeminal ganglia (TG) of mice latently infected with herpes simplex virus 1 (HSV-1) [T. Liu, K. M. Khanna, X. Chen, D. J. Fink, and R. L. Hendricks, J Exp Med 191:1459–1466, 2000, doi:10.1084/jem.191.9.1459; K. M. Khanna, R. H. Bonneau, P. R. Kinchington, and R. L. Hendricks, Immunity 18:593-603, 2003, doi:10.1016/S1074-7613(03)00112-2]. In those studies, BALB/c mice were ocularly infected with an avirulent HSV-1 strain (RE) after corneal scarification. However, in our studies, we typically infect mice with a virulent HSV-1 strain (McKrae) that does not require corneal scarification. Using a combination of knockout mice, adoptive transfers, and depletion studies, we recently found that CD8α+dendritic cells (DCs) contribute to HSV-1 latency and reactivation in TG of ocularly infected mice (K. R. Mott, S. J. Allen, M. Zandian, B. Konda, B. G. Sharifi, C. Jones, S. L. Wechsler, T. Town, and H. Ghiasi, PLoS One 9:e93444, 2014, doi:10.1371/journal.pone.0093444). This suggested that CD8+T cells might not be the major regulators of HSV-1 latency in the mouse TG. To investigate this iconoclastic possibility, we used a blocking CD8 antibody and CD8+T cells in reactivated TG explants from mice latently infected with (i) the avirulent HSV-1 strain RE following corneal scarification or (ii) the virulent HSV-1 strain McKrae without corneal scarification. Independently of the strain or approach, our results show that CD8α+DCs, not CD8+T cells, drive latency and reactivation. In addition, adoptive transfer of CD8+T cells from wild-type (wt) mice to CD8α−/−mice did not restore latency to the level for wt mice or wt virus. In the presence of latency-associated transcript (LAT(+); wt virus), CD8+T cells seem to play a bystander role in the TG. These bystander T cells highly express PD-1, most likely due to the presence of CD8α+DCs. Collectively, these results support the notion that CD8+T cells do not play a major role in maintaining HSV-1 latency and reactivation.SIGNIFICANCEThis study addresses a fundamentally important and widely debated issue in the field of HSV latency—reactivation. In this article, we directly compare the effects of anti-CD8 antibody, CD8+T cells, LAT, and CD8α+DCs in blocking explant reactivation in TG of mice latently infected with avirulent or virulent HSV-1. Our data suggest that CD8+T cells are not responsible for an increase or maintenance of latency in ocularly infected mice. However, they seem to play a bystander role that correlates with the presence of LAT, higher subclinical reactivation levels, and higher PD-1 expression levels.

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Herpes Simplex Virus 1 (HSV-1) 0ΔNLS Live-Attenuated Vaccine Protects against Ocular HSV-1 Infection in the Absence of Neutralizing Antibody in HSV-1 gB T Cell Receptor-Specific Transgenic Mice

Journal of Virology ◽

10.1128/jvi.01000-20 ◽

2020 ◽

Vol 94 (24) ◽

Author(s):

Grzegorz B. Gmyrek ◽

Adrian Filiberti ◽

Micaela Montgomery ◽

Alisha Chitrakar ◽

Derek J. Royer ◽

...

Keyword(s):

T Cells ◽

Herpes Simplex Virus ◽

Herpes Simplex ◽

T Cell ◽

Neutralizing Antibody ◽

Wild Type ◽

Herpes Simplex Virus 1 ◽

Attenuated Virus ◽

Simplex Virus ◽

Hsv 1

ABSTRACT The contribution of T cell and antibody responses following vaccination in resistance to herpes simplex virus 1 (HSV-1) infection continues to be rigorously investigated. In the present article, we explore the contribution of CD8+ T cells specific for the major antigenic epitope for HSV-1 glycoprotein B (gB498–505, gB) in C57BL/6 mice using a transgenic mouse (gBT-I.1) model vaccinated with HSV-1 0ΔNLS. gBT-I.1-vaccinated mice did not generate a robust neutralization antibody titer in comparison to the HSV-1 0ΔNLS-vaccinated wild-type C57BL/6 counterpart. Nevertheless, the vaccinated gBT-I.1 mice were resistant to ocular challenge with HSV-1 compared to vehicle-vaccinated animals based on survival and reduced corneal neovascularization but displayed similar levels of corneal opacity. Whereas there was no difference in the virus titer recovered from the cornea comparing vaccinated mice, HSV-1 0ΔNLS-vaccinated animals possessed significantly less infectious virus during acute infection in the trigeminal ganglia (TG) and brain stem compared to the control-vaccinated group. These results correlated with a significant increase in gB-elicited interferon-γ (IFN-γ), granzyme B, and CD107a and a reduction in lymphocyte activation gene 3 (LAG-3), programmed cell death 1 (PD-1), and T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3) expressed by TG infiltrating gB-specific CD8+ T cells from the HSV-1 0ΔNLS-vaccinated group. Antibody depletion of CD8+ T cells in HSV-1 0ΔNLS-vaccinated mice rendered animals highly susceptible to virus-mediated mortality similar to control-vaccinated mice. Collectively, the HSV-1 0ΔNLS vaccine is effective against ocular HSV-1 challenge, reducing ocular neovascularization and suppressing peripheral nerve virus replication in the near absence of neutralizing antibody in this unique mouse model. IMPORTANCE The role of CD8+ T cells in antiviral efficacy using a live-attenuated virus as the vaccine is complicated by the humoral immune response. In the case of the herpes simplex virus 1 (HSV-1) 0ΔNLS vaccine, the correlate of protection has been defined to be primarily antibody driven. The current study shows that in the near absence of anti-HSV-1 antibody, vaccinated mice are protected from subsequent challenge with wild-type HSV-1 as measured by survival. The efficacy is lost following depletion of CD8+ T cells. Whereas increased survival and reduction in virus replication were observed in vaccinated mice challenged with HSV-1, cornea pathology was mixed with a reduction in neovascularization but no change in opacity. Collectively, the study suggests CD8+ T cells significantly contribute to the host adaptive immune response to HSV-1 challenge following vaccination with an attenuated virus, but multiple factors are involved in cornea pathology in response to ocular virus challenge.

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Roles of Us8A and Its Phosphorylation Mediated by Us3 in Herpes Simplex Virus 1 Pathogenesis

Journal of Virology ◽

10.1128/jvi.00446-16 ◽

2016 ◽

Vol 90 (12) ◽

pp. 5622-5635 ◽

Cited By ~ 6

Author(s):

Akihisa Kato ◽

Tomoko Ando ◽

Shinya Oda ◽

Mizuki Watanabe ◽

Naoto Koyanagi ◽

...

Keyword(s):

Herpes Simplex Virus ◽

Herpes Simplex ◽

Ocular Infection ◽

Null Mutant ◽

Herpes Simplex Virus 1 ◽

The Central Nervous System ◽

Infected Cells ◽

Simplex Virus ◽

Hsv 1

ABSTRACTThe herpes simplex virus 1 (HSV-1) Us8A gene overlaps the gene that encodes glycoprotein E (gE). Previous studies have investigated the roles of Us8A in HSV-1 infection using null mutations in Us8A and gE; therefore, the role of Us8A remains to be elucidated. In this study, we investigated the function of Us8A and its phosphorylation at serine 61 (Ser-61), which we recently identified as a phosphorylation site by mass spectrometry-based phosphoproteomic analysis of HSV-1-infected cells, in HSV-1 pathogenesis. We observed that (i) the phosphorylation of Us8A Ser-61 in infected cells was dependent on the activity of the virus-encoded Us3 protein kinase; (ii) the Us8A null mutant virus exhibited a 10-fold increase in the 50% lethal dose for virulence in the central nervous system (CNS) of mice following intracranial infection compared with a repaired virus; (iii) replacement of Ser-61 with alanine (S61A) in Us8A had little effect on virulence in the CNS of mice following intracranial infection, whereas it significantly reduced the mortality of mice following ocular infection to levels similar to the Us8A null mutant virus; (iv) the Us8A S61A mutation also significantly reduced viral yields in mice following ocular infection, mainly in the trigeminal ganglia and brains; and (v) a phosphomimetic mutation at Us8A Ser-61 restored wild-type viral yields and virulence. Collectively, these results indicate that Us8A is a novel HSV-1 virulence factor and suggest that the Us3-mediated phosphorylation of Us8A Ser-61 regulates Us8A function for viral invasion into the CNS from peripheral sites.IMPORTANCEThe DNA genomes of viruses within the subfamilyAlphaherpesvirinaeare divided into unique long (UL) and unique short (Us) regions. Us regions contain alphaherpesvirus-specific genes. Recently, high-throughput sequencing of ocular isolates of HSV-1 showed that Us8A was the most highly conserved of 13 herpes simplex virus 1 (HSV-1) genes mapped to the Us region, suggesting Us8A may have an important role in the HSV-1 life cycle. However, the specific role of Us8A in HSV-1 infection remains to be elucidated. Here, we show that Us8A is a virulence factor for HSV-1 infection in mice, and the function of Us8A for viral invasion into the central nervous system from peripheral sites is regulated by Us3-mediated phosphorylation of the protein at Ser-61. This is the first study to report the significance of Us8A and its regulation in HSV-1 infection.

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Thymidine Kinase-Negative Herpes Simplex Virus 1 Can Efficiently Establish Persistent Infection in Neural Tissues of Nude Mice

Journal of Virology ◽

10.1128/jvi.01979-16 ◽

2016 ◽

Vol 91 (4) ◽

Cited By ~ 2

Author(s):

Chih-Yu Huang ◽

Hui-Wen Yao ◽

Li-Chiu Wang ◽

Fang-Hsiu Shen ◽

Sheng-Min Hsu ◽

...

Keyword(s):

T Cells ◽

Herpes Simplex Virus ◽

Herpes Simplex ◽

Thymidine Kinase ◽

Nude Mice ◽

Persistent Infection ◽

Herpes Simplex Virus 1 ◽

Neural Tissues ◽

Simplex Virus ◽

Hsv 1

ABSTRACT Herpes simplex virus 1 (HSV-1) establishes latency in neural tissues of immunocompetent mice but persists in both peripheral and neural tissues of lymphocyte-deficient mice. Thymidine kinase (TK) is believed to be essential for HSV-1 to persist in neural tissues of immunocompromised mice, because infectious virus of a mutant with defects in both TK and UL24 is detected only in peripheral tissues, but not in neural tissues, of severe combined immunodeficiency mice (T. Valyi-Nagy, R. M. Gesser, B. Raengsakulrach, S. L. Deshmane, B. P. Randazzo, A. J. Dillner, and N. W. Fraser, Virology 199:484–490, 1994, https://doi.org/10.1006/viro.1994.1150 ). Here we find infiltration of CD4 and CD8 T cells in peripheral and neural tissues of mice infected with a TK-negative mutant. We therefore investigated the significance of viral TK and host T cells for HSV-1 to persist in neural tissues using three genetically engineered mutants with defects in only TK or in both TK and UL24 and two strains of nude mice. Surprisingly, all three mutants establish persistent infection in up to 100% of brain stems and 93% of trigeminal ganglia of adult nude mice at 28 days postinfection, as measured by the recovery of infectious virus. Thus, in mouse neural tissues, host T cells block persistent HSV-1 infection, and viral TK is dispensable for the virus to establish persistent infection. Furthermore, we found 30- to 200-fold more virus in neural tissues than in the eye and detected glycoprotein C, a true late viral antigen, in brainstem neurons of nude mice persistently infected with the TK-negative mutant, suggesting that adult mouse neurons can support the replication of TK-negative HSV-1. IMPORTANCE Acyclovir is used to treat herpes simplex virus 1 (HSV-1)-infected immunocompromised patients, but treatment is hindered by the emergence of drug-resistant viruses, mostly those with mutations in viral thymidine kinase (TK), which activates acyclovir. TK mutants are detected in brains of immunocompromised patients with persistent infection. However, answers to the questions as to whether TK-negative (TK−) HSV-1 can establish persistent infection in brains of immunocompromised hosts and whether neurons in vivo are permissive for TK− HSV-1 remain elusive. Using three genetically engineered HSV-1 TK− mutants and two strains of nude mice deficient in T cells, we found that all three HSV-1 TK− mutants can efficiently establish persistent infection in the brain stem and trigeminal ganglion and detected glycoprotein C, a true late viral antigen, in brainstem neurons. Our study provides evidence that TK− HSV-1 can persist in neural tissues and replicate in brain neurons of immunocompromised hosts.

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