Functional Characterization of the Serine-Rich Tract of Varicella-Zoster Virus IE62

Kim, Seong K.; Shakya, Akhalesh Kumar; Kim, Seong‐Man; O’Callaghan, Dennis J.

doi:10.1128/jvi.02096-15

Cited by 5 publications

(6 citation statements)

References 61 publications

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“…VZV IE62 possesses an acidic transactivation domain (TAD), a serine-rich tract (SRT), and binding domains for DNA and TATA-binding protein (TBP) (39,(53)(54)(55)(56). IE62, a tegument protein, binds several viral proteins, such as ORF4 (57), ORF9 (58), ORF47 (59), and ORF63 (60), as well as cellular transcription factors, including upstream stimulatory factor (USF), TBP, mediator 25, and Sp1 (39,54,(61)(62)(63)(64)(65). Our recent studies showed that IE62 SRT is necessary for TAD-mediated transactivation and that the TAD and SRT of VZV IE62 interact with the cellular transcriptional coactivator mediator 25 and nucleolar-ribosomal EAP, respectively (54).…”

Section: Discussionmentioning

confidence: 99%

“…IE62, a tegument protein, binds several viral proteins, such as ORF4 (57), ORF9 (58), ORF47 (59), and ORF63 (60), as well as cellular transcription factors, including upstream stimulatory factor (USF), TBP, mediator 25, and Sp1 (39,54,(61)(62)(63)(64)(65). Our recent studies showed that IE62 SRT is necessary for TAD-mediated transactivation and that the TAD and SRT of VZV IE62 interact with the cellular transcriptional coactivator mediator 25 and nucleolar-ribosomal EAP, respectively (54). The SRT is necessary for the formation of large globular structures within the nucleus (54).…”

Section: Discussionmentioning

confidence: 99%

“…Our recent studies showed that IE62 SRT is necessary for TAD-mediated transactivation and that the TAD and SRT of VZV IE62 interact with the cellular transcriptional coactivator mediator 25 and nucleolar-ribosomal EAP, respectively (54). The SRT is necessary for the formation of large globular structures within the nucleus (54). The data presented in this study indicated that IFN-␥ treatment abrogated VZV IE62's transactivation activity by 95% and 97% in A549 and ARPE-19 cells, respectively (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…**, P Ͻ 0.01 for comparison with the untreated control. (E) The infected cells were harvested at 4 dpi for Western blot analyses using antibodies to the immediate early IE62 protein (54) and ␤-actin (Santa Cruz Biotechnology, Santa Cruz, CA). Data are representative of those from three independent experiments.…”

Section: Ifn-␥ Cannot Inhibit Ie62 Expression During the Ie Stage Of mentioning

confidence: 99%

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Interferon Gamma Inhibits Varicella-Zoster Virus Replication in a Cell Line-Dependent Manner

Shakya

O’Callaghan

Kim

2019

J Virol

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The major immediate early 62 (IE62) protein of varicella-zoster virus (VZV) is delivered to newly infected cell nuclei, where it initiates VZV replication by transactivating viral immediate early (IE), early (E), and late (L) genes. Interferon gamma (IFN-γ) is a potent cytokine produced following primary VZV infection. Furthermore, VZV reactivation correlates with a decline in IFN-γ-producing immune cells. Our results showed that treatment with 20 ng/ml of IFN-γ completely reduced intracellular VZV yield in A549 lung epithelial cells, MRC-5 lung fibroblasts, and ARPE-19 retinal epithelial cells at 4 days post-VZV infection. However, IFN-γ reduced virus yield only 2-fold in MeWo melanoma cells compared to that of untreated cells. IFN-β significantly inhibited VZV replication in both ARPE-19 and MeWo cells. In luciferase assays with VZV open reading frame 61 (ORF61) promoter reporter plasmid, IFN-γ abrogated the transactivation activity of IE62 by 95%, 97%, and 89% in A549, ARPE-19, and MRC-5 cells, respectively. However, IFN-γ abrogated IE62’s transactivation activity by 16% in MeWo cells, indicating that IFN-γ inhibits VZV replication as well as IE62-mediated transactivation in a cell line-dependent manner. The expression of VZV IE62 and ORF63 suppressed by IFN-γ was restored by JAK1 inhibitor treatment, indicating that the inhibition of VZV replication is mediated by JAK/STAT1 signaling. In the presence of IFN-γ, knockdown of interferon response factor 1 (IRF1) increased VZV replication. Ectopic expression of IRF1 reduced VZV yields 4,000-fold in MRC-5 and ARPE-19 cells but 3-fold in MeWo cells. These results suggest that IFN-γ blocks VZV replication by inhibiting IE62 function in a cell line-dependent manner. IMPORTANCE Our results showed that IFN-γ significantly inhibited VZV replication in a cell line-dependent manner. IFN-γ inhibited VZV gene expression after the immediate early stage of infection and abrogated IE62-mediated transactivation. These results suggest that IFN-γ blocks VZV replication by inhibiting IE62 function in a cell line-dependent manner. Understanding the mechanisms by which IFN-γ plays a role in VZV gene programming may be important in determining the tissue restriction of VZV.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Ifn-␥ Cannot Inhibit Ie62 Expression During the Ie Stage Of mentioning

confidence: 99%

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Interferon Gamma Inhibits Varicella-Zoster Virus Replication in a Cell Line-Dependent Manner

Shakya

O’Callaghan

Kim

2019

J Virol

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“…These data suggest that ISG15 functions as an antiviral molecule against EHV-1, but its mechanism of action, as well as the identity of the EHV-1 molecules that induce ISG15, remains to be determined. In this regard, comparison of alphaherpesvirus genomes showed that varicellazoster virus, pseudorabies virus, and HSV-1 are similar in structure to EHV-1 and that each of these viruses encodes a protein that shares extensive homology with the EHV-1 immediate early protein (65,66). Infection with EHV-1 wild-type strain Ab4 reduced IFN-␥ production in primary equine respiratory epithelial cells (67).…”

Section: Discussionmentioning

confidence: 99%

Immunization with Attenuated Equine Herpesvirus 1 Strain KyA Induces Innate Immune Responses That Protect Mice from Lethal Challenge

Kim

Shakya

O’Callaghan

2016

J Virol

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Equine herpesvirus 1 (EHV-1) is a major pathogen affecting equines worldwide. The virus causes respiratory disease, abortion, and, in some cases, neurological disease. EHV-1 strain KyA is attenuated in the mouse and equine, whereas wild-type strain RacL11 induces severe inflammation of the lung, causing infected mice to succumb at 4 to 6 days postinfection. Our previous results showed that KyA Equine herpesvirus 1 (EHV-1), a member of the family Herpesviridae and the subfamily Alphaherpesvirinae, is the causative agent of a number of equine pathological states, including severe disease of the central nervous system, respiratory infections, and abortion storms (1-4). Respiratory transmission of this highly contagious virus has resulted in disastrous outbreaks of disease in domestic horse populations and has had significant economic impact on the equine industry. EHV-1 infection of the horse generates a short-lived humoral response but does not confer long-term protection, since disease often occurs following natural infection (5, 6).A model that closely mimics EHV-1 infection in the natural host has been established with various strains of mice (7). Common features include replication in the respiratory mucosae, the development of pneumonitis, cell-associated viremia, and abortion (7,8). Various EHV-1 glycoproteins, including gB, gC, gD, and gH, were capable of inducing neutralizing antibodies (9-14). EHV-1-specific CD8 ϩ class I major histocompatibility complex (MHC)-restricted cytotoxic T lymphocytes (CTL) were identified in the peripheral blood mononuclear cells of infected horses, reaching maximal levels 2 to 3 weeks postinfection (15,16). Intranasal inoculation of mice with an attenuated EHV-1 strain, KyA, resulted in the production of a primary virus-specific CTL response in the draining mediastinal lymph nodes (17). In this model, EHV-1-specific CTL activity was mediated by class I MHC-restricted CD8 ϩ T cells (17). The nonpathogenic EHV-1 strain Kentucky A (KyA) is attenuated in mice and horses, whereas the wild-type pathogenic strain RacL11 induces severe inflammatory cell infiltration in the lung, such that infected mice succumb at 4 to 6 days postinfection (dpi) (Fig. 1) (18-23). RacL11 was isolated from an aborted fetus (24). KyA has a long history of passage outside the natural host and

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Analysis of IE62 mutations found in Varicella-Zoster virus vaccine strains for transactivation activity

Lee

Shin

et al. 2018

J Microbiol.

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Live attenuated vaccine strains have been developed for Varicella-Zoster virus (VZV). Compared to clinically isolated strains, the vaccine strains contain several non-synonymous mutations in open reading frames (ORFs) 0, 6, 31, 39, 55, 62, and 64. In particular, ORF62, encoding an immediate-early (IE) 62 protein that acts as a transactivator for viral gene expression, contains six non-synonymous mutations, but whether these mutations affect transactivation activity of IE62 is not understood. In this study, we investigated the role of non-synonymous vaccine-type mutations (M99T, S628G, R958G, V1197A, I1260V, and L1275S) of IE62 in Suduvax, a vaccine strain isolated in Korea, for transactivation activity. In reporter assays, Suduvax IE62 showed 2- to 4-fold lower transactivation activity toward ORF4, ORF28, ORF29, and ORF68 promoters than wild-type IE62. Introduction of individual M99T, S628G, R958G, or V1197A/I1260V/L1275S mutations into wild-type IE62 did not affect transactivation activity. However, the combination of M99T within the N-terminal Sp transcription factor binding region and V1197A/I1260V/L1275S within the C-terminal serine-enriched acidic domain (SEAD) significantly reduced the transactivation activity of IE62. The M99T/V1197A/I1260V/L1275S mutant IE62 did not show considerable alterations in intracellular distribution and Sp3 binding compared to wild-type IE62, suggesting that other alteration(s) may be responsible for the reduced transactivation activity. Collectively, our results suggest that acquisition of mutations in both Met 99 and the SEAD of IE62 is responsible for the reduced transactivation activity found in IE62 of the VZV vaccine strains and contributes to attenuation of the virus.

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Functional Characterization of the Serine-Rich Tract of Varicella-Zoster Virus IE62

Cited by 5 publications

References 61 publications

Interferon Gamma Inhibits Varicella-Zoster Virus Replication in a Cell Line-Dependent Manner

Interferon Gamma Inhibits Varicella-Zoster Virus Replication in a Cell Line-Dependent Manner

Immunization with Attenuated Equine Herpesvirus 1 Strain KyA Induces Innate Immune Responses That Protect Mice from Lethal Challenge

Analysis of IE62 mutations found in Varicella-Zoster virus vaccine strains for transactivation activity

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