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The virion host shut-off (vhs) protein blocks a TLR-independent pathway of herpes simplex virus type 1 recognition in human and mouse dendritic cells.

Cotter CR, Nguyen ML, Yount JS, López CB, Blaho JA, Moran TM - PLoS ONE (2010)

Bottom Line: These data prompted us to postulate that infection of cDCs by HSV triggers a TLR independent pathway for cDC activation that is susceptible to blockage by the vhs protein.This block to SeV- and NDV-induced activation of cDC resulted in elevated SeV and NDV viral gene expression indicating that infection with HSV-1 enhances the cell's susceptibility to other pathogens through the action of vhs.Our results demonstrate for the first time that a viral protein contained in the tegument of HSV-1 can block the induction of DC activation by TLR-independent pathways of viral recognition.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology Institute, Mount Sinai School of Medicine, New York, New York, USA.

ABSTRACT
Molecular pathways underlying the activation of dendritic cells (DCs) in response to Herpes Simplex Virus type 1 (HSV-1) are poorly understood. Removal of the HSV virion host shut-off (vhs) protein relieves a block to DC activation observed during wild-type infection. In this study, we utilized a potent DC stimulatory HSV-1 recombinant virus lacking vhs as a tool to investigate the mechanisms involved in the activation of DCs by HSV-1. We report that the release of pro-inflammatory cytokines by conventional DC (cDC) during HSV-1 infection is triggered by both virus replication-dependent and replication-independent pathways. Interestingly, while vhs is capable of inhibiting the release of cytokines during infection of human and mouse cDCs, the secretion of cytokines by plasmacytoid DC (pDC) is not affected by vhs. These data prompted us to postulate that infection of cDCs by HSV triggers a TLR independent pathway for cDC activation that is susceptible to blockage by the vhs protein. Using cDCs isolated from mice deficient in both the TLR adaptor protein MyD88 and TLR3, we show that HSV-1 and the vhs-deleted virus can activate cDCs independently of TLR signaling. In addition, virion-associated vhs fails to block cDC activation in response to treatment with TLR agonists, but it efficiently blocked cDC activation triggered by the paramyxoviruses Sendai Virus (SeV) and Newcastle Disease Virus (NDV). This block to SeV- and NDV-induced activation of cDC resulted in elevated SeV and NDV viral gene expression indicating that infection with HSV-1 enhances the cell's susceptibility to other pathogens through the action of vhs. Our results demonstrate for the first time that a viral protein contained in the tegument of HSV-1 can block the induction of DC activation by TLR-independent pathways of viral recognition.

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DCs are activated in a TLR-independent manner during HSV-1 infection.(a.) mu-cDCs isolated from MyD88, TLR3 double knock-out (DKO) and control C57BL/6 wild-type mice were infected with increasing amounts of wild-type HSV-1 (KOS). At 12 hpi, cells were harvested and released IL-6, IL-12p40, IFN-α, and IFN-β were quantitated by ELISA. (b.) RNA was extracted from the cell pellets from the above experiment and subject to qRT-PCR for the corresponding genes. Data is represented as relative expression relative to levels of housekeeping genes. CpG (6 ug/mL) was utilized to control for and confirm MyD88 deficiency; pI:C (250 ug/mL) was utilized to control for and confirm TLR3 deficiency.
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pone-0008684-g005: DCs are activated in a TLR-independent manner during HSV-1 infection.(a.) mu-cDCs isolated from MyD88, TLR3 double knock-out (DKO) and control C57BL/6 wild-type mice were infected with increasing amounts of wild-type HSV-1 (KOS). At 12 hpi, cells were harvested and released IL-6, IL-12p40, IFN-α, and IFN-β were quantitated by ELISA. (b.) RNA was extracted from the cell pellets from the above experiment and subject to qRT-PCR for the corresponding genes. Data is represented as relative expression relative to levels of housekeeping genes. CpG (6 ug/mL) was utilized to control for and confirm MyD88 deficiency; pI:C (250 ug/mL) was utilized to control for and confirm TLR3 deficiency.

Mentions: To evaluate the role of TLR signaling during HSV-1 infection of cDCs, we first infected mu-cDCs isolated from double knock-out mice deficient in both MyD88 and TLR3 with increasing amounts of wild-type HSV-1 (KOS). As shown in Figure 5a, HSV-1-infected mu-cDCs secreted pro-inflammatory cytokines (IL-6 and IL-12) and type I interferons (IFN-α and IFN-β) independently of TLR signaling and in a dose-dependent manner. This effect was also seen at the transcriptional level for KOS infection at an MOI of 5.0 (Figure 5b).


The virion host shut-off (vhs) protein blocks a TLR-independent pathway of herpes simplex virus type 1 recognition in human and mouse dendritic cells.

Cotter CR, Nguyen ML, Yount JS, López CB, Blaho JA, Moran TM - PLoS ONE (2010)

DCs are activated in a TLR-independent manner during HSV-1 infection.(a.) mu-cDCs isolated from MyD88, TLR3 double knock-out (DKO) and control C57BL/6 wild-type mice were infected with increasing amounts of wild-type HSV-1 (KOS). At 12 hpi, cells were harvested and released IL-6, IL-12p40, IFN-α, and IFN-β were quantitated by ELISA. (b.) RNA was extracted from the cell pellets from the above experiment and subject to qRT-PCR for the corresponding genes. Data is represented as relative expression relative to levels of housekeeping genes. CpG (6 ug/mL) was utilized to control for and confirm MyD88 deficiency; pI:C (250 ug/mL) was utilized to control for and confirm TLR3 deficiency.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2823768&req=5

pone-0008684-g005: DCs are activated in a TLR-independent manner during HSV-1 infection.(a.) mu-cDCs isolated from MyD88, TLR3 double knock-out (DKO) and control C57BL/6 wild-type mice were infected with increasing amounts of wild-type HSV-1 (KOS). At 12 hpi, cells were harvested and released IL-6, IL-12p40, IFN-α, and IFN-β were quantitated by ELISA. (b.) RNA was extracted from the cell pellets from the above experiment and subject to qRT-PCR for the corresponding genes. Data is represented as relative expression relative to levels of housekeeping genes. CpG (6 ug/mL) was utilized to control for and confirm MyD88 deficiency; pI:C (250 ug/mL) was utilized to control for and confirm TLR3 deficiency.
Mentions: To evaluate the role of TLR signaling during HSV-1 infection of cDCs, we first infected mu-cDCs isolated from double knock-out mice deficient in both MyD88 and TLR3 with increasing amounts of wild-type HSV-1 (KOS). As shown in Figure 5a, HSV-1-infected mu-cDCs secreted pro-inflammatory cytokines (IL-6 and IL-12) and type I interferons (IFN-α and IFN-β) independently of TLR signaling and in a dose-dependent manner. This effect was also seen at the transcriptional level for KOS infection at an MOI of 5.0 (Figure 5b).

Bottom Line: These data prompted us to postulate that infection of cDCs by HSV triggers a TLR independent pathway for cDC activation that is susceptible to blockage by the vhs protein.This block to SeV- and NDV-induced activation of cDC resulted in elevated SeV and NDV viral gene expression indicating that infection with HSV-1 enhances the cell's susceptibility to other pathogens through the action of vhs.Our results demonstrate for the first time that a viral protein contained in the tegument of HSV-1 can block the induction of DC activation by TLR-independent pathways of viral recognition.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology Institute, Mount Sinai School of Medicine, New York, New York, USA.

ABSTRACT
Molecular pathways underlying the activation of dendritic cells (DCs) in response to Herpes Simplex Virus type 1 (HSV-1) are poorly understood. Removal of the HSV virion host shut-off (vhs) protein relieves a block to DC activation observed during wild-type infection. In this study, we utilized a potent DC stimulatory HSV-1 recombinant virus lacking vhs as a tool to investigate the mechanisms involved in the activation of DCs by HSV-1. We report that the release of pro-inflammatory cytokines by conventional DC (cDC) during HSV-1 infection is triggered by both virus replication-dependent and replication-independent pathways. Interestingly, while vhs is capable of inhibiting the release of cytokines during infection of human and mouse cDCs, the secretion of cytokines by plasmacytoid DC (pDC) is not affected by vhs. These data prompted us to postulate that infection of cDCs by HSV triggers a TLR independent pathway for cDC activation that is susceptible to blockage by the vhs protein. Using cDCs isolated from mice deficient in both the TLR adaptor protein MyD88 and TLR3, we show that HSV-1 and the vhs-deleted virus can activate cDCs independently of TLR signaling. In addition, virion-associated vhs fails to block cDC activation in response to treatment with TLR agonists, but it efficiently blocked cDC activation triggered by the paramyxoviruses Sendai Virus (SeV) and Newcastle Disease Virus (NDV). This block to SeV- and NDV-induced activation of cDC resulted in elevated SeV and NDV viral gene expression indicating that infection with HSV-1 enhances the cell's susceptibility to other pathogens through the action of vhs. Our results demonstrate for the first time that a viral protein contained in the tegument of HSV-1 can block the induction of DC activation by TLR-independent pathways of viral recognition.

Show MeSH
Related in: MedlinePlus