Cyclic GMP-AMP synthase is essential for cytosolic double-stranded DNA and fowl adenovirus serotype 4 triggered innate immune responses in chickens

Differential innate immune responses to fowl adenovirus serotype 4 infection in Leghorn male hepatocellular and chicken embryo fibroblast cells

Fowl adenovirus serotype 4 (FAdV-4) infections result in substantial economic losses in the poultry industry. Recent findings have revealed that FAdV-4 significantly suppresses the host immune response upon infection; however, the specific viral and host factors contributing to this immunomodulatory activity remain poorly characterized. Moreover, diverse cell types exhibit differential immune responses to FAdV-4 infection. To elucidate cell-specific host responses, we performed transcriptomic analysis of FAdV-4 infected leghorn male hepatocellular (LMH) and chicken embryo fibroblast (CEF) cells. Although FAdV-4 replicated more efficiently in LMH cells, it provoked limited interferon-stimulated gene induction. In contrast, FAdV-4 infection triggered robust antiviral responses in CEF cells, including upregulation of cytosolic DNA sensing and interferon-stimulated genes. Knockdown of key cytosolic DNA sensing molecules enhanced FAdV-4 replication in LMH cells while reducing interferon-stimulated gene expression. Our findings reveal cell-specific virus-host interactions that provide insight into FAdV-4 pathogenesis while identifying factors that mediate antiviral immunity against FAdV-4.

Chicken Interferon-Alpha and -Lambda Exhibit Antiviral Effects against Fowl Adenovirus Serotype 4 in Leghorn Male Hepatocellular Cells

Hydropericardium hepatitis syndrome (HHS) is primarily caused by fowl adenovirus serotype 4 (FAdV-4), causing high mortality in chickens. Although vaccination strategies against FAdV-4 have been adopted, HHS still occurs sporadically. Furthermore, no effective drugs are available for controlling FAdV-4 infection. However, type I and III interferon (IFN) are crucial therapeutic agents against viral infection. The following experiments were conducted to investigate the inhibitory effect of chicken IFN against FadV-4. We expressed recombinant chicken type I IFN-α (ChIFN-α) and type III IFN-λ (ChIFN-λ) in Escherichia coli and systemically investigated their antiviral activity against FAdV-4 infection in Leghorn male hepatocellular (LMH) cells. ChIFN-α and ChIFN-λ dose dependently inhibited FAdV-4 replication in LMH cells. Compared with ChIFN-λ, ChIFN-α more significantly inhibited viral genome transcription but less significantly suppressed FAdV-4 release. ChIFN-α- and ChIFN-λ-induced IFN-stimulated gene (ISG) expression, such as PKR, ZAP, IRF7, MX1, Viperin, IFIT5, OASL, and IFI6, in LMH cells; however, ChIFN-α induced a stronger expression level than ChIFN-λ. Thus, our data revealed that ChIFN-α and ChIFN-λ might trigger different ISG expression levels, inhibiting FAdV-4 replication via different steps of the FAdV-4 lifecycle, which furthers the potential applications of IFN antiviral drugs in chickens.

The Chicken cGAS-STING Pathway Exerts Interferon-Independent Antiviral Function via Cell Apoptosis

It has been recently recognized that the DNA sensing innate immune cGAS-STING pathway exerts an IFN-independent antiviral function; however, whether and how chicken STING (chSTING) exerts such an IFN-independent antiviral activity is still unknown. Here, we showed that chSTING exerts an antiviral activity in HEK293 cells and chicken cells, independent of IFN production. chSTING was able to trigger cell apoptosis and autophagy independently of IFN, and the apoptosis inhibitors, rather than autophagy inhibitors, could antagonize the antiviral function of chSTING, suggesting the involvement of apoptosis in IFN-independent antiviral function. In addition, chSTING lost its antiviral function in IRF7-knockout chicken macrophages, indicating that IRF7 is not only essential for the production of IFN, but also participates in the other activities of chSTING, such as the apoptosis. Collectively, our results showed that chSTING exerts an antiviral function independent of IFN, likely via apoptosis.

African Swine Fever Virus L83L Negatively Regulates the cGAS-STING-Mediated IFN-I Pathway by Recruiting Tollip To Promote STING Autophagic Degradation

African swine fever (ASF) is a devastating infectious disease of pigs caused by the African swine fever virus (ASFV), which poses a great danger to the global pig industry. Many viral proteins can suppress with interferon signaling to evade the host's innate immune responses. Therefore, the development of an effective vaccine against ASFV has been dampened. Recent studies have suggested that the L83L gene may be integrated into the host genome, weakening the host immune system, but the underlying mechanism is unknown. Our study found that L83L negatively regulates the cGAS-STING-mediated type I interferon (IFN-I) signaling pathway. Overexpression of L83L inhibited IFN-β promoter and ISRE activity, and knockdown of L83L induced higher transcriptional levels of interferon-stimulated genes (ISGs) and phosphorylation levels of IRF3 in primary porcine alveolar macrophages. Mechanistically, L83L interacted with cGAS and STING to promote autophagy-lysosomal degradation of STING by recruiting Tollip, thereby blocking the phosphorylation of the downstream signaling molecules TBK1, IRF3, and IκBα and reducing IFN-I production. Altogether, our study reveals a negative regulatory mechanism involving the L83L-cGAS-STING-IFN-I axis and provides insights into an evasion strategy involving autophagy and innate signaling pathways employed by ASFV. IMPORTANCE African swine fever virus (ASFV) is a large double-stranded DNA virus that primarily infects porcine macrophages. The ASFV genome encodes a large number of immunosuppressive proteins. Current options for the prevention and control of this pathogen remain pretty limited. Our study showed that overexpression of L83L inhibited the cGAS-STING-mediated type I interferon (IFN-I) signaling pathway. In contrast, the knockdown of L83L during ASFV infection enhanced IFN-I production in porcine alveolar macrophages. Additional analysis revealed that L83L protein downregulated IFN-I signaling by recruiting Tollip to promote STING autophagic degradation. Although L83L deletion has been reported to have little effect on viral replication, its immune evade mechanism has not been elucidated. The present study extends our understanding of the functions of ASFV-encoded pL83L and its immune evasion strategy, which may provide a new basis for developing a live attenuated vaccine for ASF.

Grouper cGAS is a negative regulator of STING-mediated interferon response

Cyclic GMP-AMP synthase (cGAS) is one of the classical pattern recognition receptors that recognizes mainly intracytoplasmic DNA. cGAS induces type I IFN responses to the cGAS-STING signaling pathway. To investigate the roles of cGAS-STING signaling pathway in grouper, a cGAS homolog (named EccGAS) was cloned and identified from orange-spotted grouper (Epinephelus coioides). The open reading frame (ORF) of EccGAS is 1695 bp, encodes 575 amino acids, and contains a Mab-21 typical structural domain. EccGAS is homologous to Sebastes umbrosus and humans at 71.8% and 41.49%, respectively. EccGAS mRNA is abundant in the blood, skin, and gills. It is uniformly distributed in the cytoplasm and colocalized in the endoplasmic reticulum and mitochondria. Silencing of EccGAS inhibited the replication of Singapore grouper iridovirus (SGIV) in grouper spleen (GS) cells and enhanced the expression of interferon-related factors. Furthermore, EccGAS inhibited EcSTING-mediated interferon response and interacted with EcSTING, EcTAK1, EcTBK1, and EcIRF3. These results suggest that EccGAS may be a negative regulator of the cGAS-STING signaling pathway of fish.

Encapsulation of Platinum Prodrugs into PC7A Polymeric Nanoparticles Combined with Immune Checkpoint Inhibitors for Therapeutically Enhanced Multimodal Chemotherapy and Immunotherapy by Activation of the STING Pathway

Tumor immunotherapy has emerged as one of the most promising therapeutic methods to treat cancer. Despite its clinical application, the immunosuppressive tumor microenvironment compromises the therapeutic efficiency of this technique. To overcome this limitation, many research efforts have been devoted to the development of agents that reprogram the immunosuppressive tumor microenvironment through novel mechanisms. Over the last decade, compounds that intervene through the immunogenic stimulator of interferon genes (STING) pathway have emerged with potential for clinical development. Herein, the encapsulation of chemotherapeutic platinum complexes with a polymer with a cyclic seven-membered ring (PC7A)-based polymer into pH-responsive nanoparticles for multimodal therapeutically enhanced chemotherapy and immunotherapy is presented. This study represents the first nanomaterial with a dual activation mechanism of the STING pathway through DNA fragmentation as well as PC7A binding. The combination of these nanoparticles with immune checkpoint inhibitors demonstrates to nearly fully eradicate a colorectal tumor inside the mouse model by chemotherapy and immunotherapy using the STING pathway.

Duck cGAS inhibits DNA and RNA virus replication by activating IFNs and antiviral ISGs

Cyclic GMP-AMP Synthase (cGAS) is a pivotal adaptor of the signaling pathways involving the pattern recognition receptors and plays an important role in apoptosis and immune regulation. The cGAS function in mammals has been investigated extensively; however, the function of duck cGAS (du-cGAS) in response to viral infections is still unclear. This study aimed to clone the mallard (Anas platyrhynchos) cGAS homolog to investigate the function of duck cGAS (du-cGAS) in host antiviral innate immunity. The results showed that the open reading frame (ORF) region of the du-cGAS gene was 1296 bp, encoding 432 amino acids (aa) and exhibiting similar functional domains with its chicken counterpart. Knockdown of the endogenous du-cGAS by specific sgRNA strongly increased the replication of DNA viruses, including duck adenovirus B2 (DAdV B2) and duck short beak and dwarfism syndrome virus (SBDSV). However, the knockout did not impair the replication of novel duck reovirus (NDRV), an RNA virus. Furthermore, the mRNA expressions of type I interferon (IFNs) and vital interferon-stimulated genes (ISGs) were remarkably reduced in the du-cGAS knockout DEF cell line. Inversely, du-cGAS overexpression greatly activated the transcription of IFN-α, IFN-β, and vital ISGs, and impaired the replication of DAdV B2, SBDSV, and NDRV in the DEF cell line. Importantly, we found that a deletion of 68 aa in the N terminus didn't impair the antiviral function of du-cGAS. Overexpressing NTase Core, C-Domain (Mab21), or Zinc-Ribbon domain independently had no antiviral effects. Generally, these results reveal that du-cGAS is a vital component of the innate immune system of ducks, with a universal antiviral activity, and provides a useful strategy for the control of waterfowl viral diseases.

Chicken anemia virus VP1 negatively regulates type I interferon via targeting interferon regulatory factor 7 of the DNA-sensing pathway

The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway plays a vital role in sensing viral DNA in the cytosol, stimulating type I interferon (IFN) production and triggering the innate immune response against DNA virus infection. However, viruses have evolved effective inhibitors to impede this sensing pathway. Chicken anemia virus (CAV), a nonenveloped ssDNA virus, is a ubiquitous pathogen causing great economic losses to the poultry industry globally. CAV infection is reported to downregulate type I IFN induction. However, whether the cGAS-STING signal axis is used by CAV to regulate type I IFN remains unclear. Our results demonstrate that CAV infection significantly elevates the expression of cGAS and STING at the mRNA level, whereas IFN-β levels are reduced. Furthermore, IFN-β activation was completely blocked by the structural protein VP1 of CAV in interferon stimulatory DNA (ISD) or STING-stimulated cells. VP1 was further confirmed as an inhibitor by interacting with interferon regulatory factor 7 (IRF7) by binding its C-terminal 143-492 aa region. IRF7 dimerization induced by TANK binding kinase 1 (TBK1) could be inhibited by VP1 in a dose-dependent manner. Together, our study demonstrates that CAV VP1 is an effective inhibitor that interacts with IRF7 and antagonizes cGAS-STING pathway-mediated IFN-β activation. These findings reveal a new mechanism of immune evasion by CAV.

Goose STING mediates IFN signaling activation against RNA viruses

Stimulator of the interferon gene (STING) is involved in mammalian antiviral innate immunity as an interferon (IFN) activator. However, there is still a lack of clarity regarding the molecular characterization of goose STING (GoSTING) and its role in the innate immune response. In the present study, we cloned GoSTING and performed a series of bioinformatics analyses. GoSTING was grouped into avian clades and showed the highest sequence similarity to duck STING. The in vitro experiments showed that the mRNA levels of GoSTING, IFNs, IFN-stimulated genes (ISGs), and proinflammatory cytokines were significantly upregulated in goose embryo fibroblast cells (GEFs) infected with Newcastle disease virus (NDV). Overexpression of GoSTING in DF-1 cells and GEFs strongly activated the IFN-β promoter as detected by a dual-luciferase reporter assay. Furthermore, overexpression of GoSTING induced the expression of other types of IFN, ISGs, and proinflammatory cytokines and inhibited green fluorescent protein (GFP)-tagged NDV (NDV-GFP) and GFP-tagged vesicular stomatitis virus (VSV) (VSV-GFP) replication in vitro. In conclusion, these data suggest that GoSTING is an important regulator of the type I IFN pathway and is critical in geese’s innate immune host defense against RNA viruses.

The Porcine and Chicken Innate DNA Sensing cGAS-STING-IRF Signaling Axes Exhibit Differential Species Specificity

The innate immune DNA sensing cyclic GMP-AMP synthase (cGAS)-stimulator of IFN genes (STING) signaling pathway plays a key role in host antiviral function. Although the cGAS-STING pathway has been extensively studied, the cGAS-STING signaling in livestock and poultry is not well understood, and whether the species specificity exists is still unknown. In this study, we found that porcine and chicken STING, but not cGAS, exhibit species differences in regulation of IFN; that is, porcine (p)STING mediates good induction of IFN in mammalian cells and low IFN induction in chicken DF-1 cells; on the contrary, chicken (ch)STING mediates IFN induction only in chicken cells but not in mammalian cells. Furthermore, it was found that the motifs pLxIS of pSTING and pLxVS of chSTING are responsible for the species disparity, with the IFN activity of pSTING and chSTING exchanged by swapping the two pLxI/VS motifs. The pLxI/VS motifs mediated the interactions of various STING with downstream IFN regulatory factors (IRFs), reflecting the species-specific pIRF3 and chIRF7. Next, the STING, IRFs, and STING-IRFs were reconstituted in porcine and chicken macrophages that were genetically knocked out for STING and/or IRFs by the CRISPR-Cas9 approach. The results showed that pSTING plus pIRF3 or chIRF7 are able to induce IFN; however, chSTING plus chIRF7 but not pIRF3 are able to induce IFN, suggesting that pIRF3 is specific and stringent, which underlies the inability of chSTING to induce IFN in mammalian cells. In summary, our findings reveal the differential species specificity in the cGAS-STING pathway and the underlying mechanisms, thus providing valuable insights on the cGAS-STING-IRF signaling axis for comparative immunology.

The identification of a shorter cyclic GMP-AMP synthase gene from chickens and bioinformatics analysis of its potential signaling in IFN regulation

Chicken has an impaired innate immune system compared with mammals. Some key innate immune genes, such as Retinoic acid-inducible gene I (RIG-I), Toll like receptor 8 (TLR8), Absent in melanoma 2 (AIM2) and IFN regulatory factor 3 (IRF3), are inactivated or missing due to DNA Insertion, gene partial deletion, or gene total deletion. A predicted N-terminal deleted chicken Cyclic GMP-AMP synthase (chcGAS) gene, which is proven as the most essential cytosolic DNA sensor in other species, be obtained from the GenBank database. The large fragment deletion makes the sequence accuracy and functional integrity of the predicted chcGAS open to dispute. Here, the exact chcGAS gene was first experimentally determined by 5' and 3' rapid amplification of cDNA ends (RACE) PCR, which specifically lacked 83 amino acids in the DNA binding domain. In addition, the conservation and feasibility of cGAS-STING signaling among different species were conducted by bioinformatics to explore the possibility of the existence of the conserved pathway in chickens. The basic characteristics of the chcGAS, such as macroscopic and microscopic distribution patterns of chcGAS have been studied. In order to better research the function of chGAS, a chcGAS knockout chicken cell line has been generated by CRISPR/CAS9. Together, chicken owns an N-terminal deleted cGAS gene, and more experimental evidences are urgently needed to verify the functional integrity of chcGAS.

The Evasion of Antiviral Innate Immunity by Chicken DNA Viruses

The innate immune system constitutes the first line of host defense. Viruses have evolved multiple mechanisms to escape host immune surveillance, which has been explored extensively for human DNA viruses. There is growing evidence showing the interaction between avian DNA viruses and the host innate immune system. In this review, we will survey the present knowledge of chicken DNA viruses, then describe the functions of DNA sensors in avian innate immunity, and finally discuss recent progresses in chicken DNA virus evasion from host innate immune responses.

The fowl adenovirus serotype 4 (FAdV-4) induce cellular pathway in chickens to produce interferon and antigen-presented molecules (MHCI/II)

FAdV-4 is the major strain of adenovirus that responsible for hydro-pericardial syndrome (HPS) in poultry. In this study, the virus's specific gene fragments were isolated from clinically suspected cases and amplified by PCR. Finally, after a viral infection to investigate the immune response of the host, the gene expression of MHC (major histo-compatible) molecules (MHCIα, MHCIIβ), Ii (Invariant Chain) gene, inflammatory cytokines (IFN-β, IFN-γ, and IL-1β), and transcription factors (MDA5, STING, IRF7, and NF-kB) were detected by real-time PCR (fluorescence technology). The results of sequence comparison showed that the clinically isolated virus was 100% homologous to a virulent strain of avian adenovirus group C serotype 4 (FAdV-4), which were named AH-FAdV-4. The TCID₅₀ and pathogenicity of the virus were determined that was 10^6.52/0.1 mL with a mortality rate of 100% in chickens and 0% in ducks. Furthermore, results showed that the expression level of MHCIα, MHCIIβ, and Ii genes in chicken embryo kidney cells significantly (P < 0.01) upregulated (increased) after infection, which was 43, 5.2, and 2.5 times higher than the control group. With the addition of PDTC, an inhibitor of NF-kB, then the expression level of MHCIα, MHCIIβ, and Ii was decreased significantly (P < 0.01) than the control group. The transcription levels of these genes were decreased 0.64, 0.27, and 0.26 respectively. Simultaneously, the expression levels of IFN-β, IFN-γ, and IL-1β were also significantly (P < 0.01) up-regulated (increased) 7.8, 22.7, and 5 times higher than the control group. It was found that up-regulation of STING and NF-κB pathways are directly involved in the regulation of inflammatory cytokines (IFN-β, IFN-γ, and IL-1β), MHC molecules (MHCIα, MHCIIβ), and Ii gene. The results also showed that the gene regulation pathways consecutively increased the expression levels of MDA5, STING, IRF7, and NF-kB. It is conducted that the expression levels of cytokines, MHC molecules, and li gene were increased by STING and NF-kB pathways.

Inhibition of PARP1 Dampens Pseudorabies Virus Infection through DNA Damage-Induced Antiviral Innate Immunity

Pseudorabies virus (PRV) is the causative pathogen of Aujeszky's disease in pigs. Although vaccination is currently applied to prevent the morbidity of PRV infection, new applications are urgently needed to control this infectious disease. Poly(ADP-ribose) polymerase 1 (PARP1) functions in DNA damage repair. We report here that pharmacological and genetic inhibition of PARP1 significantly influenced PRV replication. Moreover, we demonstrate that inhibition of PARP1 induced DNA damage response and antiviral innate immunity. Mechanistically, PARP1 inhibition-induced DNA damage response resulted in the release of double-stranded DNA (dsDNA) into the cytosol, where dsDNA interacted with cyclic GMP-AMP (cGAMP) synthase (cGAS). cGAS subsequently catalyzed cGAMP production to activate the STING/TBK1/IRF3 innate immune signaling pathway. Furthermore, challenge of mice with PARP1 inhibitor stimulated antiviral innate immunity and protected mice from PRV infection in vivo. Our results demonstrate that PARP1 inhibitors may be used as a new strategy to prevent Aujeszky's disease in pigs. IMPORTANCE Aujeszky's disease is a notifiable infectious disease of pigs and causes economic losses worldwide in the pig industry. The causative pathogen is PRV, which is a member of the subfamily Alphaherpesvirinae of the family Herpesviridae. PRV has a wide range of hosts, such as ruminants, carnivores, and rodents. More seriously, recent reports suggest that PRV can cause human endophthalmitis and encephalitis, which indicates that PRV may be a potential zoonotic pathogen. Although vaccination is currently the major strategy used to control the disease, new applications are also urgently needed for the pig industry and public health. We report here that inhibition of PARP1 induces DNA damage-induced antiviral innate immunity through the cGAS-STING signaling pathway. Therefore, PARP1 is a therapeutic target for PRV infection as well as alphaherpesvirus infection.

Functionally active cyclin-dependent kinase 9 is essential for porcine reproductive and respiratory syndrome virus subgenomic RNA synthesis

Cyclin-dependent kinase 9 (CDK9) is a key regulator of RNA-polymerase II and a candidate therapeutic target for various virus infections such as respiratory syncytial virus, herpes simplex virus, human adenovirus, human cytomegalovirus, hepatitis virus B, and human papillomavirus. We employed CDK9-IN-1, a selective CDK9 inhibitor, to investigate the role of CDK9 in porcine reproductive and respiratory syndrome virus (PRRSV) infection. CDK9-IN-1 dose-dependently reduced PRRSV replication without cytotoxicity in the infected cells. The antiviral activity of CDK9-IN-1 was further confirmed by evaluating the effects of lentivirus-mediated CDK9 knockdown or CDK9 overexpression on PRRSV infection. Briefly, the depletion of CDK9 significantly inhibited viral replication, while the overexpression of CDK9 promoted viral replication. PRRSV infection also enhanced the nuclear export of CDK9 without affecting CDK9 protein expression. Viral replication cycle analyses further revealed that functionally active CDK9 in the cytosol advanced viral subgenomic RNA synthesis. Collectively, our data illustrated that CDK9 was a new host factor that was involved in PRRSV subgenomic RNA synthesis, and CDK9 inhibitor, CDK9-IN-1 was a promising antiviral candidate for PRRSV infection.

Identification of prognostic biomarkers and correlations with immune infiltrates among cGAS-STING in hepatocellular carcinoma

The cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway induces innate immunity by activating the production of inflammatory cytokines and type I interferons. Recently, studies revealed that self-DNA from by-products of chromosome instability and tumors could activate the cGAS-STING pathway, and subsequently promote or inhibit tumor development. However, the prognostic value and correlations with immune infiltrates of the cGAS-STING pathway in hepatocellular carcinoma (HCC) have not been clarified. In the present study, we used the Molecular Signatures Database, Oncomine, UALCAN, Human Protein Atlas, Kaplan–Meier plotter, LinkedOmics, and Tumor Immune Estimation Resource databases. Overexpression of XRCC5, IRF3, TRIM21, STAT6, DDX41, TBK1, XRCC6, TREX1, PRKDC, and TMEM173 was markedly correlated with clinical stages and pathological grades in HCC. Moreover, higher mRNA expression of XRCC5, XRCC6, and PRKDC was significantly related with shorter overall survival. However, higher mRNA expression of IFI16, STAT6, NLRC3, and TMEM173 was associated with favorable overall survival. Our results suggested that the kinase targets of the cGAS-STING pathway included the SRC family of tyrosine kinases (LCK and LYN), phosphoinositide 3-kinase-related protein kinase (PIKK) family kinases (ATM and ATR), and mitogen-activated protein kinase 1 (MAPK1). Furthermore, we identified significant correlations among the expression of cGAS-STING pathway and infiltration of B cells, CD4+T cells, CD8+ T cells, macrophages, neutrophils, and dendritic cells in HCC. The expression of the cGAS-STING pathway also exhibited strong relationships with diverse immune marker sets in HCC. These findings suggest that cGAS-STING pathway members may be used as prognostic biomarkers and immunotherapeutic targets HCC patients.

Chicken cGAS Senses Fowlpox Virus Infection and Regulates Macrophage Effector Functions

The anti-viral immune response is dependent on the ability of infected cells to sense foreign nucleic acids. In multiple species, the pattern recognition receptor (PRR) cyclic GMP-AMP synthase (cGAS) senses viral DNA as an essential component of the innate response. cGAS initiates a range of signaling outputs that are dependent on generation of the second messenger cGAMP that binds to the adaptor protein stimulator of interferon genes (STING). Here we show that in chicken macrophages, the cGAS/STING pathway is essential not only for the production of type-I interferons in response to intracellular DNA stimulation, but also for regulation of macrophage effector functions including the expression of MHC-II and co-stimulatory molecules. In the context of fowlpox, an avian DNA virus infection, the cGAS/STING pathway was found to be responsible for type-I interferon production and MHC-II transcription. The sensing of fowlpox virus DNA is therefore essential for mounting an anti-viral response in chicken cells and for regulation of a specific set of macrophage effector functions.

Chicken DNA Sensing cGAS-STING Signal Pathway Mediates Broad Spectrum Antiviral Functions

The innate DNA sensing receptors are one family of pattern recognition receptors and play important roles in antiviral infections, especially DNA viral infections. Among the multiple DNA sensors, cGAS has been studied intensively and is most defined in mammals. However, DNA sensors in chickens have not been much studied, and the chicken cGAS is still not fully understood. In this study, we investigated the chicken cGAS-STING signal axis, revealed its synergistic activity, species-specificity, and the signal essential sites in cGAS. Importantly, both cGAS and STING exhibited antiviral effects against DNA viruses, retroviruses, and RNA viruses, suggesting the broad range antiviral functions and the critical roles in chicken innate immunity.