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Host-interferon-stimulated gene response to virus-host recombinant variants of hepatitis E virus and enhanced viral replication.

The hepatitis E virus (HEV) is a leading cause of acute hepatitis worldwide. HEV infection can become chronic in immunocompromised individuals, in whom virus-host recombinant variants (VHRVs) can be detected. These variants often harbor host-derived insertions in the polyproline-rich region (PPR), and most display enhanced replication in vitro. However, the mechanisms underlying this replicative advantage remain unclear. It is likely that genes of the infected cells are differentially expressed according to the replicative capacity of the strain. The host factors involved in the improvement of the replicative capacity of these VHRVs are yet to be identified.In this study, we analyzed the host transcriptional response to seven VHRVs in HepG2/C3A cells using bulk RNA sequencing at 48 h and 168 h post-infection. Five VHRVs (RNF19A, ZNF787, KIF1B, RPS17, EEF1A1) previously associated with a high replication rate induced more significant, distinct transcriptomic changes than low-replicative variants (RNA18, RPL6), particularly at 168 h. A shared set of 25 genes, especially interferon-stimulated genes (ISGs), was upregulated in cells infected with high-replicating variants. Interestingly, ISG induction was limited at 48 h despite high viral RNA concentrations, suggesting a delayed antiviral response. At 168 h, high ISG expression coincided with high viral loads, indicating that VHRVs may evade or exploit immune defenses. Our findings reveal candidate ISGs such as IFIT1 and ISG15 that may influence HEV persistence and immune escape. These results offer new insights into the interplay between VHRV replication and host immunity.IMPORTANCEHepatitis E virus (HEV) is a major cause of acute hepatitis and can cause chronic infections in immunocompromised individuals. Virus-host recombinant variants (VHRVs) having integrated host-derived insertions often replicate more effectively, yet the host determinants of this phenotype remain unclear. With RNA sequencing of HepG2/C3A-infected cells, we observed that high-replicating VHRVs induce a delayed but strong expression of interferon-stimulated genes (ISGs), including IFIT1 and ISG15, despite high viral loads. These results suggest that VHRVs may transiently modulate or evade aspects of host antiviral defenses. Our study revealed host transcriptional patterns associated with enhanced viral replication, providing insight into potential mechanisms that enhance HEV replication and highlighting candidate pathways that could influence the interplay between viral replication and immune responses, all requiring further investigation.

Humans

Ischemia/Reperfusion Induces Interferon-Stimulated Gene Expression in Microglia.

Innate immune signaling is important in the pathophysiology of ischemia/reperfusion (stroke)-induced injury and recovery. Several lines of evidence support a central role for microglia in these processes. Recent work has identified Toll-like receptors (TLRs) and type I interferon (IFN) signaling in both ischemia/reperfusion-induced brain injury and ischemic preconditioning-mediated neuroprotection. To determine the effects of "ischemia/reperfusion-like" conditions on microglia, we performed genomic analyses on wild-type (WT) and TLR4-/- cultured microglia after sequential exposure to hypoxia/hypoglycemia and normoxia/normoglycemia (H/H-N/N). We observed increased expression of type 1 IFN-stimulated genes (ISGs) as the predominant transcriptomal feature of H/H-N/N-exposed WT, but not TLR4-/-, microglia. Microarray analysis on ex vivo sorted microglia from ipsilateral male mouse cortex after a transient in vivo ischemic pulse also demonstrated robust expression of ISGs. Type 1 IFNs, including the IFN-αs and IFN-β, activate the interferon-α/β receptor (IFNAR) complex. We confirmed both in vitro H/H-N/N- and in vivo ischemia/reperfusion-induced microglial ISG responses by quantitative real-time PCR and demonstrated that both were dependent on IFNAR1. We characterized the effects of hypoxia/hypoglycemia on phosphorylation of signal transducer and activator of transcription 1 (STAT1), release of type 1 IFNs, and surface expression of IFNAR1 in microglia. We demonstrated that IFN-β induces dose-dependent secretion of ISG chemokines in cultured microglia and robust ISG expression in microglia both in vitro and in vivo Finally, we demonstrated that the microglial ISG chemokine responses to TLR4 agonists were dependent on TLR4 and IFNAR1. Together, these data suggest novel ischemia/reperfusion-induced pathways for both TLR4-dependent and -independent, IFNAR1-dependent, type 1 IFN signaling in microglia.SIGNIFICANCE STATEMENT Stroke is the fifth leading cause of death in the United States and is a leading cause of serious long-term disability worldwide. Innate immune responses are critical in stroke pathophysiology, and microglia are key cellular effectors in the CNS response to ischemia/reperfusion. Using a transcriptional analysis approach, we identified a robust interferon (IFN)-stimulated gene response within microglia exposed to ischemia/reperfusion in both in vitro and in vivo experimental paradigms. Using a number of complementary techniques, we have demonstrated that these responses are dependent on innate immune signaling components including Toll-like receptor-4 and type I IFNs. We have also elucidated several novel ischemia/reperfusion-induced microglial signaling mechanisms.

Animals

No Correlation Between Interferon Signaling and Cytosolic Mitochondrial DNA/RNA Leakage in Cultured Skin Fibroblasts of Patients With Mitochondrial Diseases.

Mitochondria have long been known to be involved in the regulation of innate immune response. We questioned whether cultured skin fibroblasts of patients suffering from mitochondrial diseases are valuable biological resources for the study of interferon signaling. Expression of interferon-stimulated genes was measured in control cells supplemented with interferon and in cultured fibroblasts of patients carrying pathogenic variants in mitochondrial disease-causing genes. Control fibroblasts showed a strong expression of interferon-stimulated genes in response to interferon, but only 43% of patients' fibroblasts displayed increased interferon stimulated genes scores. Cytosolic mitochondrial DNA and RNA were quantified by immunofluorescence and confocal microscopy. No correlation between elevated interferon response and cytosolic mitochondrial DNA or RNA release could be established. We found that cultured skin fibroblasts represent a valuable biological resource for the investigation of interferon signaling, but that abnormal interferon signaling is not always observed in patients with mitochondrial diseases. At variance to gene silencing in control fibroblasts, the lack of correlation between elevated interferon response and cytosolic mitochondrial DNA or RNA leakage in patients' fibroblasts questions the relevance of cellular models as illustrators of pathological situations in humans.

Humans

Inhibiting cyclin D1-CDK6 suppresses senescence-associated inflammatory gene expression and age-related functional decline.

Cellular senescence contributes to aging and age-related diseases by driving chronic inflammation through the senescence-associated secretory phenotype (SASP), including interferon-stimulated genes (ISGs). Here we confirm and extend previous observations that cyclin D1 (CCND1), a key cell cycle regulator, is paradoxically upregulated across models of nonproliferating senescent cells. We show that CCND1 and its kinase partner CDK6 drive SASP and ISG expression in senescent cells by promoting DNA damage accumulation. This leads to the formation of cytoplasmic chromatin fragments that activate pro-inflammatory cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling. In aged mouse livers, senescent hepatocytes show increased Ccnd1 expression. Hepatocyte-specific Ccnd1 knockout or treatment with the clinical grade CDK4/6 inhibitor palbociclib reduces DNA damage and ISGs in aged mouse liver. Further, palbociclib suppresses frailty and improves physical performance of aged mice. These findings demonstrate a role for CCND1/CDK6 in regulating DNA damage and inflammation in senescence and aging, highlighting it as a promising target for therapeutic repurposing.

Animals

Identification of a prognostic signature consisting of three macrophage-related genes for glioblastoma based on bulk and single-cell transcriptomes analyses.

BACKGROUND: Tumor-associated macrophages have been implicated in the progression and treatment resistance of glioblastoma (GBM). This study aimed to identify macrophage-related genes associated with prognosis and therapeutic response in GBM. MATERIALS AND METHODS: Bulk RNA-seq data from 533 patients with GBM were downloaded from the Cancer Genome Atlas (TCGA) and Chinese Glioma Genome Atlas (CGGA) databases. Bioinformatic tools were used to detect the co-expression gene modules associated with the infiltration of immune cells, identify a prognostic macrophage-related gene signature, and explore their association with sensitivity to chemotherapeutic drugs and immune checkpoint blockade. Single-cell RNA-seq data and multiplexed immunofluorescence were used to validate ISG20 expression (a member of the identified gene signature) in macrophages. RESULTS: We detected gene modules associated with macrophages and identified a signature consisting of three macrophage-related genes (ISG20, PARP12 and IFIT5) in the discovery set (TCGA-GBM, n = 159), and validated its prognostic value in the validation set (CGGA-GBM, n = 374). This gene signature demonstrated favorable accuracy in predicting prognosis and resistance of immuno- and chemo-therapy. The co-expression of ISG20 and PD-1 in macrophages was verified by single-cell RNA-seq data and multiplex immunofluorescence. CONCLUSIONS: This study presents a macrophage-related gene signature to predict prognosis and therapeutic response in GBM. ISG20, PARP12 and IFIT5 are interferon-stimulated genes, and further investigations may provide new insights into the interplay between macrophages and interferon signaling in GBM.

Humans

Innate immune sensing and signaling: Co-opted for genome surveillance? Implications for tumorigenesis.

Innate immune signaling is traditionally associated with the response to pathogenic infection. However, emerging evidence suggests that nuclear innate immune sensors and their downstream pathways may also serve as a critical mechanism for genome surveillance. This review explores a model in which DNA sensors such as mouse IFI204 and IFI205 (IFI16 in humans) localize to replication forks, where they detect endogenous aberrant DNA structures and initiate an interferon-stimulated gene (ISG) transcriptional program. A key output of this transcriptional program is ISG15, which we find conjugated to fork-associated proteins and facilitates recruitment of the replication fork protection complex, thereby stabilizing replication forks under physiological conditions. We discuss how nuclear innate immune sensors mediate replication stress sensing and examine the broad consequences of downstream ISG transcription across diverse contexts-including its impact on genome stability and its dual roles in modulating tumor cell behavior and the tumor microenvironment. These findings suggest that the innate immune system, through its nuclear DNA sensing arm, may be evolutionarily co-opted for genome surveillance and may influence tumor initiation and therapy resistance. Understanding how innate immune signaling intersects with replication stress could offer mechanistic insights into tumor development and reveal novel therapeutic targets.

Humans

Alu Overexpression Leads to an Increased Double-Stranded RNA Signature in Dermatomyositis.

OBJECTIVE: Dermatomyositis is an autoimmune condition characterized by a high interferon signature of unknown etiology. Because coding sequences constitute <1.2% of our genomes, there is a need to explore the role of the noncoding genome in disease pathogenesis. Our genomes include roughly 1.2 million Alu elements occupying approximately 10% of the genome, which can form double-stranded (ds) RNA capable of triggering MDA5 leading to interferon production. METHODS: We aligned muscle biopsy RNA sequencing data to the telomere-to-telomere reference genome and quantified short interspersed elements including Alus. Because Alus have a propensity to form dsRNA and are the major targets of both adenosine deaminase RNA specific and MDA5, we quantified adenosine to inosine (A-to-I) RNA editing, which reflects dsRNA in vivo. RESULTS: Dermatomyositis muscle (n = 39) showed a global elevation in Alu expression (including inverted-repeat Alus with high potential to form dsRNA) as well as an increased expression of unique Alu elements (n = 557, q < 0.05) compared with healthy controls (n = 34), in a pattern not seen in other myositis types (n = 81). Most (75.3%) of these Alus originated from genomic regions outside genes. A cluster of the uniquely overexpressed Alus (n = 167) correlated with interferon-stimulated genes and markers of myositis activity. Additionally, we found a uniquely expanded Alu A-to-I editome in dermatomyositis, reflecting an increase in dsRNA. Edited Alus clustered on chromosome 19, which is known to have the highest concentration of dsRNA. CONCLUSION: We hypothesize that overexpressed Alus in dermatomyositis form endogenous dsRNA that exceeds the capacity of RNA editing enzymes and triggers dsRNA sensors leading to interferon production.

Humans

VHL synthetic lethality screens uncover CBF-&#x3b2; as a negative regulator of STING.

Clear cell renal cell carcinoma (ccRCC) represents the most common form of kidney cancer and is typified by biallelic inactivation of the von Hippel-Lindau (VHL) tumour suppressor gene. Here, we undertake genome-wide CRISPR/Cas9 screening to reveal synthetic lethal interactors of VHL, and uncover that loss of Core Binding Factor &#x3b2; (CBF-&#x3b2;) causes cell death in VHL-null ccRCC cell lines and impairs tumour establishment and growth in vivo. This synthetic relationship is independent of the elevated activity of hypoxia inducible factors (HIFs) in VHL-null cells, but does involve the RUNX transcription factors that are known binding partners of CBF-&#x3b2;. Mechanistically, CBF-&#x3b2; loss leads to upregulation of type I interferon signalling, and we uncover a direct inhibitory role for CBF-&#x3b2; at the STING locus controlling Interferon Stimulated Gene expression. Targeting CBF-&#x3b2; in kidney cancer both selectively induces tumour cell lethality and promotes activation of type I interferon signalling.

Humans

Crosstalk mediators implicated in the Stevens-Johnson Syndrome through gene regulatory network analysis.

Stevens-Johnson syndrome (SJS) is a rare and severe mucocutaneous disorder often triggered by medications or infections. Our previous research identified that four key genes, Ikzf1, Ptger3, Mavs, and Tlr3 are involved in SJS susceptibility and the conjunctival epithelial innate immune response, demonstrating their role in regulating interferon-stimulated genes. However, the interplay among these regulatory factors remains unclear. This study aimed to elucidate the crosstalk mechanisms between the pathways regulated by these four genes in conjunctival epithelial cells. We constructed a comprehensive gene regulatory network using transcriptomic data from murine conjunctival epithelial cells under 16 distinct conditions, including polyI:C stimulation across wild-type, knockout, and transgenic backgrounds for the key genes. A targeted network analysis systematically identified numerous candidate genes mediating the crosstalk between the regulatory pathways initiated by Ikzf1, Ptger3, Mavs, and Tlr3. The identified candidates suggest the involvement of diverse signaling pathways previously unlinked to SJS pathology. Our findings suggest that the pathogenesis of SJS may arise not from the dysfunction of isolated genes but from the disruption of a balance maintained by intricate pathway crosstalk.

Animals

Translating single-cell RNA sequencing into monocyte direct leukocyte subpopulation-transcript abundance assay ratio-based biomarkers (IFI27/PSAP or IFI27/CTSS) for clinical detection of viral infection.

A rapid method for triaging febrile patients by aetiology (e.g., viral or bacterial infection) using gene expression in peripheral blood (PB) is an intensively researched area. However, gene expression in blood represents a composite sum of gene expression of all the component cell types present in the sample. As a result, numerous genes are measured in most proposed signatures. Herein, we propose a simple ratio-based biomarker (RBB) called direct leukocyte subpopulation-transcript abundance assay (DIRECT LS-TA) that recapitulates gene expressions of a single cell type in PB (i.e., monocytes). Based on single-cell RNA sequencing (scRNAseq) data and bulk expression data, IFI27 and SIGLEC1 are found as interferon-stimulated genes (ISGs) predominantly expressed by monocytes. The DIRECT LS-TA method can use a simple ratio of two genes measured in PB as an RBB to represent the target gene expression in monocytes without the need for monocyte purification. Both scRNAseq and bulk RNA sequencing datasets were used to evaluate the correlation between ISG expression in monocytes and PB, with a particular focus on monocyte expression of IFI27. An iceberg plot of bulk transcriptome data was used to identify genes that were predominantly expressed by monocytes in PB. DIRECT LS-TA RBBs of the three genes (IFI27, IFI44L and SIGLEC1) were evaluated by group-wise comparison, receiver operating characteristic and meta-analysis. In addition, the conventional interferon (IFN) score was evaluated for comparison of diagnostic performance. In viral infection datasets, DIRECT LS-TA of IFI27 (IFI27/PSAP or IFI27/CTSS) was most intensely activated (p value by t test <1e-9) and had the best area under the curve (0.94) among the three potential monocyte ISGs analysed. DIRECT LS-TA SIGLEC1 was also another monocyte biomarker but showed a lower activation (p<9e-5). IFI27/PSAP showed better diagnostic performance than the conventional IFN score. On the other hand, IFI44L was not a predominant monocyte expression gene. DIRECT LS-TA of IFI27 (IFI27/PSAP or IFI27/CTSS) measured in PB was the best biomarker of viral infection and IFN activation among ISGs predominantly expressed by monocytes. It performed even better than the conventional IFN score which required quantification of eight genes. The results suggest that DIRECT LS-TA of IFI27 is a monocyte-informative biomarker which is easy to determine in PB without the need for cell sorting.

Humans

Regnase-1-mediated regulation of neutrophils modulates SARS-CoV-2 pneumonia.

The innate immune response to viral infection needs to be tightly regulated to ensure effective pathogen clearance while avoiding excessive immune activation. During SARS-CoV-2 infection, however, the immune system often fails to elicit appropriate responses, resulting in cytokine-release syndrome in patients with COVID-19. In this study, we show that reduced expression of Regnase-1, an RNase that negatively regulates immune cell activation, confers resistance to infection with the mouse-adapted SARS-CoV-2 MA10 strain. In Regnase-1+/- mice, altered neutrophil function contributed to the amelioration of MA10-induced pneumonia. Single-cell RNA sequencing of lung tissue during MA10 infection revealed four distinct neutrophil subsets, and among these, a subset characterized by an interferon-stimulated gene (ISG) signature was decreased in Regnase-1+/- mice. Furthermore, Regnase-1+/- neutrophils exhibited reduced ISG expression without corresponding changes in proinflammatory gene expression. Regnase-1 was found to repress the expression of Tsc22d3, a gene involved in the negative regulation of interferon responses, through its 3' untranslated region. Collectively, these findings suggest that Regnase-1 attenuates resistance to SARS-CoV-2 MA10 infection by promoting excessive interferon responses in neutrophils.

Animals

Transcriptomic and Proteomic Insights into Mucosal Immune Responses of Asian Seabass (Lates calcarifer) After Sequential Mucosal Vaccination Against Bacterial Pathogens.

Bacterial diseases caused by Flavobacterium covae (Fc), Vibrio harveyi (Vh), Vibrio vulnificus (Vv) and Photobacterium damselae (Pd) seriously constrain Asian seabass aquaculture. Here we dissect the mucosal immune mechanisms engaged by a five-month sequential vaccination strategy that combines nanoemulsion immersion priming with multivalent oral hydrogel boosting. Juvenile seabass were vaccinated, then challenged with F. covae by freshwater immersion and with a Vibrio-Photobacterium (Vh/Vv/Pd) mix by immersion or intraperitoneal injection. Gills were sampled after immersion challenges and intestine after injection, and profiled by RNA sequencing and label-free quantitative proteomics, with selected genes validated by RT-qPCR. Principal component analysis showed clear separation of vaccinated and control fish in all tissues and challenges, indicating a strong and coherent transcriptional reprogramming. Vaccination markedly increased the number of upregulated genes, with Gene Ontology enrichment revealing dominant signatures of ribosome biogenesis, RNA processing, lysosomal organization and immune response. KEGG analysis highlighted cytokine receptor interaction; NOD and Toll-like receptor signaling; oxidative phosphorylation; and phagosome, lysosome and cell adhesion molecule pathways, consistent with heightened antimicrobial readiness. Volcano plots and focused heatmaps showed strong induction of interferon-stimulated genes, cytokines and chemokine receptors, complement components, macrophage mannose receptor, epithelial barrier mediators and numerous immunoglobulin transcripts, with tissue- and challenge-specific patterns. Proteomics corroborated these trends, demonstrating a higher abundance of immunoglobulin heavy chains, complement proteins, cathepsins, heat shock and redox chaperones, ribosomal proteins and cytoskeletal and adhesion regulators in vaccinated mucosae. Integrated pathway mapping linked endothelial adhesion molecules and leukocyte integrins with T cell costimulation networks and an intestinal immune network for immunoglobulin production, including enhanced pIgR-mediated transcytosis. Overall, the sequential vaccination regimen was associated with coordinated transcriptomic and proteomic signatures related to epithelial responses, innate immunity, and humoral immune functions across gill and intestinal tissues. These molecular patterns were accompanied by improved survival following bacterial challenge; however, the present data do not directly demonstrate the functional activity of the inferred immune mechanisms in Asian seabass.

Animals

Intestinal plasmacytoid dendritic cells preferentially produce interferon lambda, contributing to localized innate immune responses.

The healthy intestine maintains homeostasis in part via immune responses to microbiota, which includes basal production of interferon cytokines. Previous work showed that Type III Interferon (IFN-&#x3bb;) stimulates localized pockets of interferon-stimulated genes (ISGs) in the adult mouse intestinal epithelium at homeostasis that provide preemptive protection from viral pathogens. Here, we demonstrate that a major source of homeostatic IFN-&#x3bb; production in the intestine is a population of epithelium-associated plasmacytoid dendritic cells (pDC). Expansion of the pDC population increases epithelial ISG expression at homeostasis, suggesting the abundance of these cells is a limiting factor in IFN-&#x3bb; responses. On the other hand, depletion of pDC or bone marrow reconstitution with IFN-&#x3bb;-deficient pDC results in reduced expression of homeostatic ISGs in the intestinal epithelium. Notably, intestinal pDC preferentially produce homeostatic IFN-&#x3bb;, whereas splenic pDC produce Type I IFNs. Comparison of intestinal and splenic pDC reveal tissue-specific changes in gene expression and genomic accessibility, including evidence of responses to transforming growth factor beta (TGF-&#x3b2;) in the intestine. Isolated gut pDC produce more IFN-&#x3bb; than splenic pDC upon stimulation, and pretreatment of a human pDC cell line with TGF-&#x3b2; results in enhanced transcription of IFN-&#x3bb; upon stimulation. This study demonstrates that pDC are a substantial source of homeostatic IFN-&#x3bb; in the intestine and implicates the barrier cytokine TGF-&#x3b2; in regulating IFN types produced by pDC upon stimulation. Reprogramming of recruited pDC by tissue cytokines may have important implications for balancing effective antimicrobial responses with damaging inflammation at barrier tissues.

Animals

Impaired hematopoiesis and embryonic lethality at midgestation of mice lacking both lipid transfer proteins VPS13A and VPS13C.

VPS13 is the founding member of a family of proteins that mediate lipid transfer at intracellular membrane contact sites by a bridge-like mechanism. Mammalian genomes comprise 4 VPS13 genes encoding proteins with distinct localizations and function. The gene duplication resulting in VPS13A and VPS13C is the most recent in evolution and, accordingly, these two proteins are the most similar to each other. However, they have distinct subcellular localizations and their loss of function mutations in humans are compatible with life but result in two different age-dependent neurodegenerative diseases, chorea-acanthocytosis and Parkinson's disease, respectively. Thus, it remains unclear whether these two proteins have overlapping functions. Here, we show that while Vps13a KO and Vps13c KO mice are viable, embryonic development of Vps13a/Vps13c double knockout (DKO) mice is arrested at midgestation. Prior to death, DKO embryos were smaller than controls, were anemic and had a smaller liver, most likely reflecting defective embryonic erythropoiesis which at this developmental stage occurs primarily in this organ. Further analyses of erythroid precursor cells showed that their differentiation was impaired and that this defect was accompanied by activation of innate immunity as revealed by upregulation of interferon stimulated genes (ISGs). Additionally, the RIG-I and MDA5 components of dsRNA triggered innate immunity were found upregulated in the DKO fetal liver. Activation of innate immunity may result from loss of integrity of the membranes of intracellular organelles, such as mitochondria and autophagic lysosomes, or to impaired autophagy, due to the absence of these lipid transport proteins. The surprising and striking synthetic effect resulting for the combined loss of VPS13A and VPS13C suggests that despite of the different localization of these two proteins, the lipid fluxes that they mediate are partially redundant.

Animals

Intranasal neomycin evokes broad-spectrum antiviral immunity in the upper respiratory tract.

Respiratory virus infections in humans cause a broad-spectrum of diseases that result in substantial morbidity and mortality annually worldwide. To reduce the global burden of respiratory viral diseases, preventative and therapeutic interventions that are accessible and effective are urgently needed, especially in countries that are disproportionately affected. Repurposing generic medicine has the potential to bring new treatments for infectious diseases to patients efficiently and equitably. In this study, we found that intranasal delivery of neomycin, a generic aminoglycoside antibiotic, induces the expression of interferon-stimulated genes (ISGs) in the nasal mucosa that is independent of the commensal microbiota. Prophylactic or therapeutic administration of neomycin provided significant protection against upper respiratory infection and lethal disease in a mouse model of COVID-19. Furthermore, neomycin treatment protected Mx1 congenic mice from upper and lower respiratory infections with a highly virulent strain of influenza A virus. In Syrian hamsters, neomycin treatment potently mitigated contact transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In healthy humans, intranasal application of neomycin-containing Neosporin ointment was well tolerated and effective at inducing ISG expression in the nose in a subset of participants. These findings suggest that neomycin has the potential to be harnessed as a host-directed antiviral strategy for the prevention and treatment of respiratory viral infections.

Animals

Mycobacterium tuberculosis Rv0158 negatively regulates the cGAS-STING pathway mediated type I IFN production and enhances intracellular survival.

BACKGROUND: Type I interferons (IFN) play an important role in the host defense against Mycobacterium tuberculosis (M. tb) infection and disease pathogenesis. Although M. tb has evolved several mechanisms to evade host immune surveillance, the mechanism used to regulate type I IFN expression remains unclear. METHODS: In this study, genome-wide high-throughput loss-of-function screening was performed to screen M. tb determinants that regulate the Type I IFN pathway, and the role for M. tb Rv0158 in inhibiting type I IFN responses was identified in vitro and in vivo. RESULTS: The M. tb coding protein Rv0158 was identified among many transposon (Tn) insertion mutants, which increased the expression of IFN-&#x3b2; and some pro-inflammatory cytokines. The results suggested that Rv0158 is associated with reduced STING protein levels and suppression of cGAS-STING-mediated innate immune responses, suggesting that Rv0158 may indirectly facilitate STING degradation or modulate its stability through host-interacting partners. Rv0158 also down-regulated the transcription of interferon-stimulated genes (ISGs) and increased the bacterial load in mice. CONCLUSION: Overall, our finding identified a new bacterial factor Rv0158, these results reveal an important role for M. tb Rv0158 in inhibiting Type I IFN responses, which improves our understanding of the immune evasion mechanisms of M. tb.

Immune escape

Modeling reptile virus infection in vitro using Python regius airway organoids.

Zoonoses pose substantial global health risks, highlighting the need to better understand animal-to-human transmission. Reptiles are increasingly recognized as hosts of diverse pathogens, including numerous viruses, yet the diversity and prevalence of reptile pathogens, as well as their potential risk to humans, remain poorly understood. Here, we establish and characterize airway organoids derived from Python regius, providing an in vitro model to study reptile airway infection. Through de novo assembly of a Python regius reference genome, we characterize airway organoids at single-cell resolution, which suggests the presence of diverse cell populations including ionocytes, ciliated, secretory, goblet, endocrine, tuft, and basal cells. The organoids support productive infection with Ball Python Nidovirus (BPNV) and mount a robust epithelial antiviral response through the&#xa0;induction of interferon-stimulated genes, cytokines, and genes involved in chemical defense. As a proof-of-concept, treating organoids with antiviral drugs during infection reduces BPNV levels, highlighting the model's utility for drug testing. By providing a reductionist system of the serpentes airway, these organoids constitute a physiologically relevant in vitro model to study reptile viruses and host-pathogen interactions in their native host.

Animals

Defining the host dependencies and the transcriptional landscape of RSV infection and bystander activation.

Respiratory syncytial virus (RSV) is a globally prevalent pathogen, causes severe disease in older adults, and is the leading cause of bronchiolitis and pneumonia in the United States for children during their first year of life [1]. Despite its prevalence worldwide, RSV-specific treatments remain unavailable for most infected patients. Here, we leveraged a combination of genome-wide CRISPR knockout screening and single-cell RNA sequencing to improve our understanding of the host determinants of RSV infection and the host response in both infected cells, and uninfected bystanders. These data reveal temporal transcriptional patterns that are markedly different between RSV infected and bystander activated cells. Our data show that expression of interferon-stimulated genes is primarily observed in bystander activated cells, while genes implicated in the unfolded protein response and cellular stress are upregulated specifically in RSV infected cells. Furthermore, genome-wide CRISPR screens identified multiple host factors important for viral infection, findings which we contextualize relative to 29 previously published screens across 17 additional viruses. These unique data complement and extend prior studies that investigate the proinflammatory response to RSV infection, and juxtaposed to other viral infections, provide a rich resource for further hypothesis testing.

CRISPR screen