Human cytomegalovirus UL36 inhibits IRF3-dependent immune signaling to counterbalance its immunoenhancement as apoptotic inhibitor

Targeting STING antagonism in HSV-1: A peptide-based strategy to restore antiviral immunity and suppress viral pathogenesis

Herpes simplex virus 1 (HSV-1) poses significant threats to human health. Wang et al.1 show that the HSV-1 protein directly antagonizes stimulator of interferon genes (STING). A designed peptide derived from STING can restore virus-subverted immunity and inhibit HSV-1 replication and pathogenesis in mice.

Herpes simplex virus 1 encodes a STING antagonist that can be therapeutically targeted

Herpes simplex virus 1 (HSV-1) is a ubiquitous human pathogen that causes serious symptoms and is known for its strong interactions with host immunity. Here, we revealed that the HSV-1-encoded UL38 is a stimulator of interferon genes (STING) antagonist that interacts with STING to abrogate the STING-TANK-binding kinase 1 (TBK1)-interferon regulatory factor 3 (IRF3) interaction, thereby suppressing cyclic GMP-AMP synthase (cGAS)-STING-dependent immune signaling. Losing UL38's STING antagonist activity made HSV-1 incapable of immune evasion and less replicable and pathogenic in vivo. Moreover, on the basis of the UL38-interacting sequence within STING, we rationally designed a series of peptides to target the STING-UL38 interface of UL38 specifically. Among them, a peptide effectively disrupts the STING-UL38 interaction, which unlocks the UL38-suppressed immune response and shows potent therapeutic efficacy against HSV-1 infection in vivo. Therefore, our findings demonstrate that HSV-1 UL38 is a STING antagonist, and targeting the activity of UL38 is a promising strategy for the development of antivirals against this notorious virus.

Spatial Analysis of Placentae During Congenital Cytomegalovirus Infection Reveals Distinct Cellular Profiles in Immune Cells and Trophoblasts

Cytomegalovirus (CMV) is the most common cause of birth defects by an infectious agent. Approximately 10% of infants with congenital CMV (cCMV) infection are symptomatic. Infected infants can exhibit long-term effects such as sensorineural hearing and vision loss and neurodevelopmental delay. To date, the mechanisms by which cCMV infection results in symptomatic disease are incompletely understood. The placenta has been implicated as a main thoroughfare for vertical transmission, as both placental immune cells and trophoblasts can be infected by CMV. The goal of this study was to spatially investigate changes in genes and proteins from immune cells and trophoblasts during cCMV infection. Utilizing the NanoString GeoMx Digital Spatial Profiler, we noted that both immune cells and trophoblasts in CMV + placentae exhibited increased expression and upregulation of immune activation receptors and pathways. Pro-apoptotic proteins were decreased in CMV + placentae, as were transcripts associated with cell death pathways. Spatially, immune cells infiltrating into CMV + placental villi had more CD4 + T cells expressing cell death markers than those T cells in the decidua (p = 0.002). In contrast, the decidua exhibited a CD8+ T cell abundance with far less upregulation of immune activation receptors than in the villi (p=0.03). These data can inform and direct future research into the immune mechanisms CMV uses to infect, evade, and vertically transmit the virus to the fetus.

Human cytomegalovirus: pathogenesis, prevention, and treatment

Human cytomegalovirus (HCMV) infection remains a significant global health challenge, particularly for immunocompromised individuals and newborns. This comprehensive review synthesizes current knowledge on HCMV pathogenesis, prevention, and treatment strategies. We examine the molecular mechanisms of HCMV entry, focusing on the structure and function of key envelope glycoproteins (gB, gH/gL/gO, gH/gL/pUL128-131) and their interactions with cellular receptors such as PDGFRα, NRP2, and THBD. The review explores HCMV's sophisticated immune evasion strategies, including interference with pattern recognition receptor signaling, modulation of antigen presentation, and regulation of NK and T cell responses. We highlight recent advancements in developing neutralizing antibodies, various vaccine strategies (live-attenuated, subunit, vector-based, DNA, and mRNA), antiviral compounds (both virus-targeted and host-targeted), and emerging cellular therapies such as TCR-T cell approaches. By integrating insights from structural biology, immunology, and clinical research, we identify critical knowledge gaps and propose future research directions. This analysis aims to stimulate cross-disciplinary collaborations and accelerate the development of more effective prevention and treatment strategies for HCMV infections, addressing a significant unmet medical need.

Exploring the interaction mechanisms between cervical carcinoma in situ and antibody-mediated immune responses through Mendelian randomization analysis

OBJECTIVE

This study aims to investigate the causal relationship between cervical carcinoma in situ and antibody-mediated immune responses, providing a scientific basis for the prevention and treatment of cervical carcinoma in situ.

METHODS

A bidirectional Mendelian Randomization (MR) approach was utilized, leveraging two Genome-Wide Association Studies (GWAS) related to cervical carcinoma in situ and antibody-mediated immune responses to collect Single Nucleotide Polymorphism (SNP) data. Multiple statistical methods, including the inverse-variance weighted (IVW) method, MR-Egger regression, weighted median, and weighted mode, were utilized. Antibody-mediated immune response-related SNPs were used as instrumental variables (IVs) for a forward MR analysis of cervical carcinoma in situ, while cervical carcinoma in situ-related SNPs served as IVs for a reverse MR analysis of antibody-mediated immune responses.

RESULTS

The forward MR analysis revealed significant causal associations between two SNPs, GCST90006901 (P = 0.012, OR (95%CI) = 1.167(1.034-1.317)) and GCST90006909 (P < 0.001, OR (95%CI) = 1.805(1.320-2.467)), within antibody-mediated immune responses and the occurrence of cervical carcinoma in situ. The reverse MR analysis demonstrated that cervical carcinoma in situ exerts influence on multiple SNPs associated with antibody-mediated immune responses. Specifically, GCST90006891 (P = 0.018, OR (95%CI) = 1.164(1.027-1.319)) and GCST90006894 (P = 0.048, OR (95%CI) = 1.074 (1.001-1.153)) showed positive effects, while GCST90006899 (P = 0.022, OR (95%CI) = 0.935(0.882-0.990)) and GCST90006911 (P = 0.0193, OR (95%CI) = 1.226(1.034-1.454)) exhibited distinct trends of influence.

CONCLUSION

The Mendelian Randomization analysis indicates a clear causal relationship between antibody-mediated immune responses and the prevalence of cervical carcinoma in situ, with cervical carcinoma in situ also exerting a certain degree of influence on antibody-mediated immune responses. This finding provides important insights into the interaction mechanism between the two and suggests avenues for developing effective prevention and control strategies.

Simultaneously Controlling Inflammation and Infection by Smart Nanomedicine Responding to the Inflammatory Microenvironment

The overactivated immune cells in the infectious lesion may lead to irreversible organ damages under severe infections. However, clinically used immunosuppressive anti-inflammatory drugs will usually disturb immune homeostasis and conversely increase the risk of infections. Regulating the balance between anti-inflammation and anti-infection is thus critical in treating certain infectious diseases. Herein, considering that hydrogen peroxide (H2O2), myeloperoxidase (MPO), and neutrophils are upregulated in the inflammatory microenvironment and closely related to the severity of appendectomy patients, an inflammatory-microenvironment-responsive nanomedicine is designed by using poly(lactic-co-glycolic) acid (PLGA) nanoparticles to load chlorine E6 (Ce6), a photosensitizer, and luminal (Lum), a chemiluminescent agent. The obtained Lum/Ce6@PLGA nanoparticles, being non-toxic within normal physiological environment, can generate cytotoxic single oxygen via bioluminescence resonance energy transfer (BRET) in the inflammatory microenvironment with upregulated H2O2 and MPO, simultaneously killing pathogens and excessive inflammatory immune cells in the lesion, without disturbing immune homeostasis. As evidenced in various clinically relevant bacterial infection models and virus-induced pneumonia, Lum/Ce6@PLGA nanoparticles appeared to be rather effective in controlling both infection and inflammation, resulting in significantly improved animal survival. Therefore, the BRET-based nanoparticles by simultaneously controlling infections and inflammation may be promising nano-therapeutics for treatment of severe infectious diseases.

The battle between host antiviral innate immunity and immune evasion by cytomegalovirus

Cytomegalovirus (CMV) has successfully established a long-lasting latent infection in humans due to its ability to counteract the host antiviral innate immune response. During coevolution with the host, the virus has evolved various evasion techniques to evade the host's innate immune surveillance. At present, there is still no vaccine available for the prevention and treatment of CMV infection, and the interaction between CMV infection and host antiviral innate immunity is still not well understood. However, ongoing studies will offer new insights into how to treat and prevent CMV infection and its related diseases. Here, we update recent studies on how CMV evades antiviral innate immunity, with a focus on how CMV proteins target and disrupt critical adaptors of antiviral innate immune signaling pathways. This review also discusses some classic intrinsic cellular defences that are crucial to the fight against viral invasion. A comprehensive review of the evasion mechanisms of antiviral innate immunity by CMV will help investigators identify new therapeutic targets and develop vaccines against CMV infection.

Cytomegalovirus inhibitors of programmed cell death restrict antigen cross-presentation in the priming of antiviral CD8 T cells

CD8 T cells are the predominant effector cells of adaptive immunity in preventing cytomegalovirus (CMV) multiple-organ disease caused by cytopathogenic tissue infection. The mechanism by which CMV-specific, naïve CD8 T cells become primed and clonally expand is of fundamental importance for our understanding of CMV immune control. For CD8 T-cell priming, two pathways have been identified: direct antigen presentation by infected professional antigen-presenting cells (pAPCs) and antigen cross-presentation by uninfected pAPCs that take up antigenic material derived from infected tissue cells. Studies in mouse models using murine CMV (mCMV) and precluding either pathway genetically or experimentally have shown that, in principle, both pathways can congruently generate the mouse MHC/H-2 class-I-determined epitope-specificity repertoire of the CD8 T-cell response. Recent studies, however, have shown that direct antigen presentation is the canonical pathway when both are accessible. This raised the question of why antigen cross-presentation is ineffective even under conditions of high virus replication thought to provide high amounts of antigenic material for feeding cross-presenting pAPCs. As delivery of antigenic material for cross-presentation is associated with programmed cell death, and as CMVs encode inhibitors of different cell death pathways, we pursued the idea that these inhibitors restrict antigen delivery and thus CD8 T-cell priming by cross-presentation. To test this hypothesis, we compared the CD8 T-cell responses to recombinant mCMVs lacking expression of the apoptosis-inhibiting protein M36 or the necroptosis-inhibiting protein M45 with responses to wild-type mCMV and revertant viruses expressing the respective cell death inhibitors. The data reveal that increased programmed cell death improves CD8 T-cell priming in mice capable of antigen cross-presentation but not in a mutant mouse strain unable to cross-present. These findings strongly support the conclusion that CMV cell death inhibitors restrict the priming of CD8 T cells by antigen cross-presentation.

Herpes Simplex Virus-1 targets the 2'-3'cGAMP importer SLC19A1 as an antiviral countermeasure

To establish a successful infection, herpes simplex virus-1 (HSV-1), a virus with high seropositivity in the human population, must undermine host innate and intrinsic immune defense mechanisms, including the stimulator of interferon genes (STING) pathway. Recently it was discovered that not only de novo produced intracellular 2'-3'cGAMP, but also extracellular 2'-3'cGAMP activates the STING pathway by being transported across the cell membrane via the folate transporter, SLC19A1, the first identified extracellular antiporter of this signaling molecule. We hypothesized that the import of exogenous 2'-3'cGAMP functions to establish an antiviral state like that seen with the paracrine antiviral activities of interferon. Further, to establish a successful infection, HSV-1 must undermine this induction of the STING pathway by inhibiting the biological functions of SLC19A1. Herein, we report that treatment of the monocytic cell line, THP-1 cells, epithelial cells (ARPE-19) and SH-SY5Y neuronal cell line with exogenous 2'-3'cGAMP induces interferon production and establishes an antiviral state. Using either pharmaceutical inhibition or genetic knockout of SLC19A1 blocks the 2'-3'cGAMP-induced antiviral state. Additionally, HSV-1 infection results in the reduction of SLC19A1 transcription, translation, and importantly, the rapid removal of SLC19A1 from the cell surface of infected cells. Our data indicate SLC19A1 functions as a newly identified antiviral mediator for extracellular 2'-3'cGAMP which is undermined by HSV-1. This work presents novel and important findings about how HSV-1 manipulates the host's immune environment for viral replication and discovers details about an antiviral mechanism which information could aid in the development of better antiviral drugs in the future.

Importance

HSV-1 has evolved multiple mechanisms to neutralize of the host's innate and intrinsic defense pathways, such as the STING pathway. Here, we identified an antiviral response in which extracellular 2'-3'cGAMP triggers IFN production via its transporter SLC19A1. Moreover, we report that HSV-1 blocks the functions of this transporter thereby impeding the antiviral response, suggesting exogenous 2'-3'cGAMP can act as an immunomodulatory molecule in uninfected cells to activate the STING pathway, and priming an antiviral state, similar to that seen in interferon responses. The details of this mechanism highlight important details about HSV-1 infections. This work presents novel findings about how HSV-1 manipulates the host's immune environment for viral replication and reveals details about a novel antiviral mechanism. These findings expand our understanding of how viral infections undermine host responses and may help in the development of better broad based antiviral drugs in the future.