Activation of NF-κB in CD8 ⁺ Dendritic Cells Ex Vivo by the γ ₁ 34.5 Null Mutant Correlates with Immunity against Herpes Simplex Virus 1

Abstract

The ␥ 1 34.5 protein of herpes simplex viruses (HSV) is essential for virulence. Accordingly, an HSV mutant lacking ␥ 1 34.5 is attenuated in vivo. Despite its vaccine potential, the mechanism by which the ␥ 1 34.5 null mutant triggers protective immunity is unknown. In this report we show that vaccination with the ␥ 1 34.5 null mutant protects against lethal challenge from wild-type virus via IB kinase in dendritic cells (DCs), which sense virus-associated molecular patterns. Unlike mock-treated DCs, DCs primed with the ␥ 1 34.5 null mutant ex vivo mediate resistance to wild-type HSV after adoptive transfer into naïve mice. Furthermore, the ␥ 1 34.5 null mutant activates IB kinase, which facilitates p65/RelA phosphorylation and nuclear translocation, resulting in DC maturation. While unable to produce infectious virus in DCs, this mutant virus expresses early and late genes. In its abortive infection, the ␥ 1 34.5 null mutant induces protective immunity more effectively in CD8 ؉ DCs than in CD8 ؊ DCs. This is mirrored by a higher level of interleukin-6 (IL-6) and IL-12 secretion by CD8 ؉ DCs than CD8 ؊ DCs. Remarkably, inhibition of p65/RelA phosphorylation or nuclear translocation in CD8 ؉ DCs disrupts protective immunity. These results suggest that engagement of the ␥ 1 34.5 null mutant with CD8 ؉ DCs elicits innate immunity to activate NF-B, which translates into protective immunity. Herpes simplex viruses (HSVs) are human pathogens responsible for a spectrum of diseases, including ocular lesions, genital herpes, and encephalitis (11). HSV infection is also a risk factor in HIV acquisition and transmission. Following infection, HSV initiates a lytic cycle in the mucosal tissues, where viral gene transcription, replication, assembly, and egress ensue. This is followed by a latency in sensory ganglia, where reactivation occurs intermittently, resulting in recurrent infections (11). In this process, HSV interacts with host cells, including dendritic cells (DCs), which capture, process, and present viral antigens. Upon maturation, DCs express high levels of costimulatory molecules. Additionally, DCs release inflammatory cytokines to induce T cell responses that restrict viral infection (1, 54, 68).DCs detect HSV through multiple pathways (22,48,50). For example, plasmacytoid DCs detect HSV through Toll-like receptor 9 (TLR9), whereas conventional DCs sense virus via TLRdependent and -independent pathways (22,32,48). It is thought that HSV proteins or RNA intermediates trigger conventional DCs (22,48). Notably, a complex consisting of HSV glycoproteins B, D, H, and L stimulates DC maturation (50). On the other hand, HSV blocks DC activities (3,26,28,52). In immature DCs, HSV type 1 (HSV-1) downregulates cell surface molecules and cytokines, impairing T cell activation (10, 26, 38, 44, 52). HSV-1 also induces apoptosis of DCs, whereas HSV-2 exerts this activity more rapidly (5, 26, 44). Further, HSV-1 perturbs mature DCs (28, 45), where it induces degradation of CD83 (28, 29). Moreover, HSV-1 reduces levels of che...

Herpes Simplex Virus 1 Protein Kinase US3 Hyperphosphorylates p65/RelA and Dampens NF-κB Activation

“…ϩ DCs (56). The large genome of HSV-1 therefore enables the encoding of numerous proteins that modulate host innate immune responses.…”

Herpes Simplex Virus 1 E3 Ubiquitin Ligase ICP0 Protein Inhibits Tumor Necrosis Factor Alpha-Induced NF-κB Activation by Interacting with p65/RelA and p50/NF-κB1

“…ICP27, an immediate early gene product of HSV-1, has been shown to antagonize NF-B signaling (17). The ␥ 1 34.5 protein, an HSV-1-encoded late-gene product, inhibits activation of NF-B in CD8 ϩ dendritic cells (DCs) (18). Vhs, a tegument protein, blocks the early replication-independent activation of NF-B in HSV-1-infected DCs (19).…”

Type I Interferon and NF-κB Activation Elicited by Herpes Simplex Virus gH/gL via αvβ3 Integrin in Epithelial and Neuronal Cell Lines

“…Alternatively, the model HEK-293T cells have been employed in such studies (10). The roles of the various branches of the innate response to HSV in cell targets of the infection, e.g., epithelial and neuronal cells, have so far received little attention, apart from a number of studies focused on in vivo or ex vivo responses (9,(15)(16)(17).Recently, we reported that ␣v␤3 integrin serves as a novel sensing system for HSV (18). It elicits the production of IFN-␣ and -␤ and a specific set of cytokines and receptors, interleukin-10 (IL-10), IL-2, and IL2R, as well as NF-B activation (18).…”

“…Alternatively, the model HEK-293T cells have been employed in such studies (10). The roles of the various branches of the innate response to HSV in cell targets of the infection, e.g., epithelial and neuronal cells, have so far received little attention, apart from a number of studies focused on in vivo or ex vivo responses (9,(15)(16)(17).…”

“…The endosomal TLR3 and TLR7, as well as the cytoplasmic RIG-I (RNA helicase retinoic acid-inducible gene I), sense single-or double-stranded RNAs. The endosomal TLR9 and a number of cytosolic molecules, such as DAI (DNAdependent activator of interferon-regulatory factor), IFI16 (gamma interferon-inducible protein 16), and AIM2 (absent in melanoma 2), etc., sense double-stranded DNA (2,3).…”