Search Results (695)

The innate immune response is an important defense against invading pathogens. Stimulator of interferon gene (STING) plays an important role in the cyclic GMP-AMP synthase (cGAS)-mediated activation of type I IFN responses. However, some viruses have evolved the ability to inhibit the function of STING and evade the host antiviral defenses. Understanding both the mechanism of action and the viruses targets of STING effector is important because of their importance to evade the host antiviral defenses. In this study, the STING (IpSTING) of Ictalurus punctatus was first identified and characterized. Subsequently, the yeast two-hybrid system (Y2HS) was used to screen for proteins from channel catfish virus (CCV, Ictalurid herpesvirus 1) that interact with IpSTING. The ORFs of the CCV were cloned into the pGBKT7 vector and expressed in the AH109 yeast strain. The bait protein expression was validated by autoactivation, and toxicity investigation compared with control (AH109 yeast strain transformed with empty pGBKT7 and pGADT7 vector). Two positive candidate proteins, ORF41 and ORF65, were identified through Y2HS screening as interacting with IpSTING. Their interactions were further validated using co-immunoprecipitation (Co-IP). This represented the first identification of interactions between IpSTING and the CCV proteins ORF41 and ORF65. The data advanced our understanding of the functions of ORF41 and ORF65 and suggested that they might contribute to the evasion of host antiviral defenses. However, the interaction mechanism between IpSTING, and CCV proteins ORF41 and ORF65 still needs to be further explored. Full article

Interferon (IFN) signaling plays vital roles in host defense against viral infection. However, a variety of observations have been reported in the literature regarding the roles of IFN signaling in COVID-19. Thus, it would be important to reach a clearer picture regarding the activation or suppression of IFN signaling in COVID-19. In this work, regulation of marker genes for IFN signaling was examined in natural infection, viral challenge, and vaccination based on 13 public transcriptome datasets. Three subsets of interferon-stimulated genes (ISGs) were selected for detailed examination, including one set of marker genes for type I IFN signaling (ISGa) and two sets of marker genes for type II IFN signaling (IFN-γ signaling, GBPs for the GBP gene cluster, and HLAd for the HLA-D gene cluster). In natural infection, activation of ISGa and GBPs was accompanied by the suppression of HLAd in hospitalized patients. Suppression of GBPs was also observed in certain critical conditions. The scale of regulation was much greater for ISGa than that of GBPs and HLAd. In addition, the suppression of HLAd was correlated with disease severity, and it took much longer for HLAd to return to the level of healthy controls than that for ISGa and GBPs. Upon viral challenge, the activation of ISGa and GBPs was similar to that of natural infection, while the suppression of HLAd was not observed. Moreover, GBPs’ return to the pre-infection level was at a faster pace than that of ISGa. Upon COVID-19 vaccination, activation was observed for all of these three gene sets, and the scale of activation was comparable for ISGa and GBPs. Notably, it took a much shorter time for GBPs and ISGa to return to the level of healthy controls than that in COVID-19 infection. In addition, the baseline values and transient activation of these gene sets were also associated with subsequent vaccination response. The intricate balance of IFN signaling was demonstrated in mild breakthrough infection, where attenuated response was observed in people with prior vaccination compared to that in vaccine-naïve subjects. Overall, distinctive temporal profiles of IFN signaling were observed in natural infection, viral challenge, and vaccination. The features observed in this work may provide novel insights into the disease management and vaccine development. Full article

Myxoma virus (MYXV), a rabbit-specific poxvirus and non-pathogenic in humans and mice, is an excellent candidate oncolytic virus for cancer therapy. MYXV also has immunotherapeutic benefits. In ovarian cancer (OC), immunosuppressive tumor-associated macrophages (TAMs) are key to inhibiting antitumor immunity while hindering therapeutic benefit by chemotherapy and dendritic cell (DC) vaccine. Because MYXV favors binding/entry of macrophages/monocytes, we examined the therapeutic potential of MYXV against TAMs. We found previously that a replication-defective MYXV with targeted deletion of an essential gene, M062R, designated ΔM062R MYXV, activated both the host DNA sensing pathway and the SAMD9 pathway. Treatment with ΔM062R confers therapeutic benefit comparable to that of wild-type replicating MYXV in preclinical models. Here we found that ΔM062R MYXV, when integrated with cisplatin and DC immunotherapy, further improved treatment benefit, likely through promoting tumor antigen-specific T cell function. Moreover, we also tested ΔM062R MYXV in targeting human immunosuppressive TAMs from OC patient ascites in a co-culture system. We found that ΔM062R treatment subverted the immunosuppressive properties of TAMs and elevated the avidity of cytokine production in tumor antigen-specific CD4⁺ T cells. Overall, ΔM062R presents a promising immunotherapeutic platform as a beneficial adjuvant to chemotherapy and DC vaccine. Full article

Porcine epidemic diarrhea virus (PEDV) infection induces severe, often fatal, watery diarrhea and vomiting in neonatal piglets, characterized by profound dehydration, villus atrophy, and catastrophic mortality rates approaching 100% in unprotected herds. This study developed a composite probiotic from Min-pig-derived Lactobacillus crispatus LCM233, Ligilactobacillus salivarius LSM231, and Lactiplantibacillus plantarum LPM239, which exhibited synergistic growth, potent acid/bile salt tolerance, and broad-spectrum antimicrobial activity against pathogens. In vitro, the probiotic combination disrupted pathogen ultrastructure and inhibited PEDV replication in IPI-2I cells. In vivo, PEDV-infected piglets administered with the multi-strain probiotic exhibited decreased viral loads in anal and nasal swabs, as well as in intestinal tissues. This intervention was associated with the alleviation of diarrhea symptoms and improved weight gain. Furthermore, the multi-strain probiotic facilitated the repair of intestinal villi and tight junctions, increased the number of goblet cells, downregulated pro-inflammatory cytokines, enhanced the expression of barrier proteins, and upregulated antiviral interferon-stimulated genes. These findings demonstrate that the multi-strain probiotic mitigates PEDV-induced damage by restoring intestinal barrier homeostasis and modulating immune responses, providing a novel strategy for controlling PEDV infections. Full article

Interferon-induced transmembrane protein 3 (IFITM3) is a member of the family of interferon-stimulated genes (ISGs) that inhibits a diverse array of enveloped viruses which enter host cells by endocytosis. Porcine reproductive and respiratory syndrome virus (PRRSV) is an enveloped RNA virus causing significant economic losses to the swine industry. Very little is known regarding how IFITM3 restricts PRRSV. In this study, the role of IFITM3 in PRRSV infection was studied in vitro using MARC-145 cells. IFITM3 over-expression reduced PRRSV replication, while the siRNA-induced knockdown of endogenous IFITM3 increased PRRSV RNA copies and virus titers. The colocalization of the virus with IFITM3 was observed at both 3 and 24 h post infection (hpi). Quantitative analysis of confocal microscopic images showed that an average of 73% of IFITM3-expressing cells were stained positive for PRRSV at 3 hpi, while only an average of 27% of IFITM3-expressing cells were stained positive for PRRSV at 24 hpi. These findings suggest that IFITM3 may restrict PRRSV at the post-entry steps. Future studies are needed to better understand the mechanisms by which this restriction factor inhibits PRRSV. Full article

The B-cell adapter for PI3K (BCAP) is a protein that connects membrane receptor signaling to the PI3K pathway. In fibroblasts or dendritic cells, priming the cGAS nucleic-acid-sensing pathway increases BCAP expression and enhances type I interferon (IFN-I) production upon lipopolysaccharide (LPS) stimulation. These findings corroborate the idea that BCAP may bias cytokine production toward IFN during inflammation, indicating its potential involvement in IFN-driven diseases like systemic lupus erythematosus (SLE). We investigate the role of BCAP in regulating the inflammatory response in SLE and its relationship with IFN-mediated inflammation. BCAP gene expression and IFN signature were analyzed in 36 subjects with SLE and 20 healthy controls. Two cellular models were used to assess BCAP’s role in LPS response and IFN signaling after cGAS stimulation. We found a correlation between BCAP and interferon-stimulated gene (ISG) expression in SLE. In a cellular model, tofacitinib and anifrolumab, acting as IFN signaling “inhibitors”, blocked BCAP overexpression triggered by cGAS, confirming BCAP as an ISG. Additional studies in BCAP^−/− cells revealed that, in the absence of BCAP, these cells exhibited diminished IFN production upon LPS stimulation following prior exposure to cGAMP. Overall, BCAP is an ISG that acts as a positive regulator of Toll-like receptor 4-mediated IFN production. We speculate that its increased expression in SLE may contribute to a positive feedback loop, enhancing IFN production during bacterial infections. Full article

SLE is characterized by the generation of a variety of autoantibodies including anti-dsDNA autoantibodies, causing damage in various organs. If autoimmunity is defined by the generation of a variety of autoantibodies against the self, SLE is the only disease to qualify. Identification of the SLE-causing factor must fulfill the following criteria: (i) the factor induces SLE, (ii) the factor is operating in active SLE and (iii) SLE heals after removal of the factor. All candidate factors are reviewed from this viewpoint in this review. As to the cause of SLE, high levels of interferon α can induce SLE; however, interferon α in most patients did not reach this high level. BAFF (B cell activating factor of the TNF family) is increased in SLE. BAFF itself induced some manifestation of SLE, whereas removal of interferon α or BAFF by an antibody (Ab) did not heal SLE. BXSB male mice with a duplicated TLR7 gene develop SLE; however, the gene Sle1 is also required for the development of SLE. In addition, sanroque mice develop a variety of autoantibodies and SLE; the sanroque mutation, which disrupts one of the repressors of ICOS, results in increased CCR7^lo CXCR5⁺Tfh cells, IL-21 and SLE. ICOS⁺T follicular helper (Tfh) cells increase in SLE and SLE-model (NZBxNZW)F1 mice, and the blockade of Tfh development ameliorated SLE, indicating the importance of Tfh cells in the pathogenesis of SLE. Self-organized criticality theory shows that SLE is caused by repeated infection, wherein SLE-inducing pathogens can vary individually depending on one’s HLA; however, the pathogen presented on HLA stimulates the T cell receptor (TCR) strongly beyond self-organized criticality. This stimulation generates TCR-revised, autoreactive DOCK8⁺Tfh cells, which induced a variety of autoantibodies and SLE. The SARS-CoV-2 virus is an example pathogen because SLE occurs after SARS-CoV-2 infection and vaccination. DOCK8⁺Tfh cells and SLE decreased after conventional or anti-DOCK Ab therapies. Thus, DOCK8⁺Tfh cells newly generated after repeated infection fulfill the criteria (i), (ii) and (iii) as the cause of SLE. Full article

Early embryonic loss is a major cause of reproductive inefficiency in cattle, primarily due to premature luteolysis. Interferon tau (IFN-τ), secreted by the trophoblast, plays a critical role in maternal recognition of pregnancy by maintaining corpus luteum function. However, its practical application has been limited by its rapid degradation and short half-life in vivo. Here, we developed a novel formulation of recombinant bovine IFN-τ, combining chitosan-based microencapsulation with starch–chitosan hydrogel delivery, enabling sustained intrauterine release. This dual-delivery strategy offers a significant improvement over conventional IFN-τ administration methods that rely on repeated intrauterine infusions of soluble protein. The rbIFN-τ was expressed in Pichia pastoris, purified to 90.1% homogeneity, and structurally validated via homology modeling and molecular docking, confirming its interaction with type I interferon receptors. The encapsulated formulation retained antiviral activity, stimulated transcription of interferon-stimulated genes (PKR, OAS1, OAS2), and showed sustained release in vitro for up to 26 days. In vivo evaluation demonstrated safety and biological efficacy, with treated cattle showing inhibited luteolysis, sustained serum progesterone levels, and preserved corpus luteum integrity. This formulation represents a promising biotechnological approach to improve reproductive efficiency through a long-acting, species-specific IFN-τ delivery system. Full article

Background: Vaccines represent one of the most affordable and efficient tools for controlling infectious diseases; however, the development of efficacious vaccines against complex pathogens remains a major challenge. Adjuvants play a relevant role in enhancing vaccine-induced immune responses. One such molecule is interferon-stimulated gene 15 (ISG15), a key modulator of antiviral immunity that acts both through ISGylation-dependent mechanisms and as a cytokine-like molecule. Methods: In this study, we assessed the immunostimulatory potential of ISG15 as an adjuvant in Modified Vaccinia virus Ankara (MVA)-based vaccine candidates targeting Zika virus (ZIKV) and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Early innate responses and immune cell infiltration were analyzed in immunized mice by flow cytometry and cytokine profiling. To elucidate the underlying mechanism of action of ISG15, in vitro co-infection studies were performed in macrophages. Finally, we evaluated the magnitude and functional quality of the elicited antigen-specific cellular immune responses in vivo. Results: Analysis of early innate responses revealed both platform- and variant-specific effects. ISG15AA preferentially promoted natural killer (NK) cell recruitment at the injection site, whereas ISG15GG enhanced myeloid cell infiltration in draining lymph nodes (DLNs), particularly when delivered via MVA. Moreover, in vitro co-infection of macrophages with MVA-based vaccine vectors and the ISG15AA mutant led to a marked increase in proinflammatory cytokine production, highlighting a dominant role for the extracellular, ISGylation-independent functions of ISG15 in shaping vaccine-induced immunity. Notably, co-infection of ISG15 with MVA-ZIKV and MVA-SARS-CoV-2 vaccine candidates enhanced the magnitude of antigen-specific immune responses in both vaccine models. Conclusions: ISG15, particularly in its ISGylation-deficient form, acts as a promising immunomodulatory adjuvant for viral vaccines, enhancing both innate and adaptive immune responses. Consistent with previous findings in the context of Human Immunodeficiency virus type 1 (HIV-1) vaccines, this study further supports the potential of ISG15 as an effective adjuvant for vaccines targeting viral infections such as ZIKV and SARS-CoV-2. Full article

Dengue virus (DENV) infection is strongly associated with dengue hemorrhagic fever and dengue shock syndrome, both of which carry mortality risks. Addressing the urgent need for effective dengue therapeutics, we identified sofalcone, a gastroprotective agent with antioxidant and anti-inflammatory properties, as a potential inhibitor of DENV replication. Sofalcone demonstrated efficacy against all four DENV serotypes, with the dose inhibiting 50% (IC50) value of 28.1 ± 0.42 μM against viral replication of DENV serotype 2, without significant cytotoxicity. Additionally, sofalcone significantly improved survival rates and reduced viral titers in DENV-infected ICR-suckling mice. Mechanistically, sofalcone induced heme oxygenase-1 (HO-1) expression via the nuclear factor-erythroid 2-reated factor 2 (Nrf2) pathway, which in turn suppressed viral protease activity and restored antiviral interferon (IFN) responses. This included dose-dependent stimulation of IFN downstream antiviral genes such as 2′-5′-oligoadenylate synthetase 1 (OAS1), OAS2, and OAS3. Given its established clinical use as an anti-gastric ulcer drug, sofalcone offers promising potential for rapid application in treating DENV infection. Full article

Background: The STING (Stimulator of Interferon Genes) pathway plays a vital role in the body’s innate immune defense system, primarily involved in DNA sensing and type I interferon production. While STING is well-established in various immune cells, its role in natural killer (NK) cells, particularly within the context of liver fibrosis, remains inadequately explored. Aim: The current study investigates the relationship between STING expression, NK cell activity, and insulin receptor (IR) signaling in patients with metabolic dysfunction-associated steatohepatitis (MASH). Methods: Peripheral NK cells were isolated from healthy controls and MASH patients with varying stages of liver fibrosis (early: F1/F2; advanced: F3/F4). The expressions of STING, IR, NK cell activation markers (CD107a, NKp46), and NK cell inhibitory markers (LAIR-1, Siglec-7) were assessed using flow cytometry. NK cell cytotoxicity against primary hepatic stellate cells (pHSCs) was evaluated through apoptosis assays. STING agonists (2′3′-cGAMP and DMXAA) were used to stimulate NK cells, and their effects on STING expression, NK cell activation, and cytotoxicity were measured. Additionally, the impact of insulin signaling on STING expression and NK cell function was examined. Results: Our results demonstrate that STING expression in NK cells correlates with disease severity in liver fibrosis. NK cells from MASH patients with advanced fibrosis (F3/F4) showed inhibited STING protein levels that were statistically comparable to healthy NK cells and accompanied by impaired cytotoxicity and decreased IFN-γ production. In contrast, NK cells from early fibrosis (F1/F2) exhibited higher STING expression and better functional activity. STING agonist treatment (2′3′-cGAMP) restored STING expression and enhanced NK cell activity across all fibrosis stages. Furthermore, insulin treatment and combined insulin and 2′3′-cGAMP treatment synergistically upregulated both IR and STING expressions, leading to improved NK cell function and increased cytotoxicity, particularly in advanced fibrosis. Conclusion: Our results highlight the potential of targeting STING and insulin signaling pathways as a therapeutic approach in restoring NK cell function and enhance immune surveillance in liver fibrosis. Full article

The DNA-damage response (DDR) network and the immune system are significant mechanisms linked to the normal functioning of living organisms. Extensive observations suggest that agents that damage the DNA can boost immunity in various ways, some of which may be useful for immunotherapeutic applications. Indeed, the immune system can be activated by the DDR network through a number of different mechanisms, such as via (a) an increase in the tumor neoantigen burden, (b) the induction of the stimulator of interferon genes pathway, (c) the triggering of immunogenic cell death, (d) an increase in antigen presentation as a result of the augmented expression of the major histocompatibility complex type I molecule, (e) modification of the cytokine milieu in the tumor microenvironment, and (f) altered expression of the programmed cell death ligand-1. Together, the DDR network may improve the effect of immunostimulatory anticancer agents and provide a basis for devising more efficient treatment strategies, such as combinatorial therapies of DDR targeting drugs and immunomodulators. Here, the molecular mechanisms underlying the immune system’s activation by DDR are summarized, along with some of their possible uses in cancer treatment. Full article

The immediate-early protein IE180 of pseudorabies virus (PRV) is a multifunctional regulator of viral and host gene expression. However, its role in modulating antiviral immune responses remains poorly understood. Here, we demonstrate that IE180 overexpression significantly inhibits PRV and H1N1 influenza virus replication in Hep2 and A549 cells, respectively. Mechanistically, IE180 activates the type I interferon (IFN-I) pathway by enhancing IFN-β promoter activity and IFN transcription, leading to upregulated expression of interferon-stimulated genes (ISGs). Notably, IE180 failed to suppress PRV or H1N1 replication in Vero cells, which lack functional IFN-I signaling, confirming the dependence of its antiviral function on the IFN-I pathway. Domain mapping revealed that the ICP4-Like2 domain of IE180 is critical for IFN-β activation and antiviral activity. These findings establish IE180 as a novel viral immunomodulator that activates host innate immunity to restrict viral replication, providing insights into PRV-host interactions and potential therapeutic strategies. Full article

Interferon (IFN)-induced proteins with tetratricopeptide repeats (IFITs) are key interferon-stimulated genes (ISGs), and in humans include IFIT1, IFIT2, IFIT3 and IFIT5. These proteins are primarily known for their role in the innate immune response to pathogens. However, growing evidence suggests that IFITs participate in a range of other cellular processes, including cancer development and progression. Notably, IFITs may behave in either a pro-oncogenic or tumor suppressive fashion depending on cancer types and emphasizing their potential dual function in tumorigenesis. Importantly, IFITs have shown potential to be utilized as clinical biomarkers in oncology. Their aberrant expression has been correlated with survival and other clinical outcomes, including resistance to radiotherapy, chemotherapy, targeted treatments and immunotherapy in various cancers. Additionally, they have also been reported to be a part of various clinical predictive models in cancers. This review provides an overview of the current understanding of IFIT proteins’ involvement in cancers, with an emphasis on their emerging roles as clinically relevant biomarkers. Full article

The pandemic of Coronavirus Disease 2019 has triggered a worldwide public health emergency. Its pathogen, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has developed multiple strategies for effectively evading the host immune defenses, including inhibition of interferon (IFN) signaling. Several viral proteins of SARS-CoV-2 are believed to interfere with IFN signaling. In this study, we found that the SARS-CoV-2 accessory protein ORF7a considerably impaired IFN-activated Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling via suppression of the nuclear translocation of IFN-stimulated gene factor 3 (ISGF3) and the activation of STAT2. ORF7a dampened STAT2 activation without altering the expression and phosphorylation of Janus kinases (JAKs). A co-immunoprecipitation (co-IP) assay was performed to gather ORF7a protein, but it failed to precipitate STAT2. Interestingly, mass spectrometry and immunoblotting analyses of the ORF7a co-IP product revealed that ORF7a interacted with an RNA-binding protein, heterogeneous nuclear ribonucleoprotein A2B1 (HNRNPA2B1), and HNRNPA2B1 was related to the inhibitory effect of ORF7a on STAT2 phosphorylation. Moreover, examination of ORF7a deletion constructs revealed that the C-terminal region of ORF7a (amino acids 96 to 122) is crucial for suppressing IFN-induced JAK/STAT signaling activation. In conclusion, we discovered that SARS-CoV-2 ORF7a antagonizes type I IFN-activated JAK/STAT signaling by interacting with HNRNPA2B1, and the C-terminal region of ORF7a is responsible for its inhibitory effect. Full article