Genetic manipulation of Patescibacteria provides mechanistic insights into microbial dark matter and the epibiotic lifestyle.

Patescibacteria, also known as the candidate phyla radiation (CPR), are a diverse group of bacteria that constitute a disproportionately large fraction of microbial dark matter. Its few cultivated members, belonging mostly to Saccharibacteria, grow as epibionts on host Actinobacteria. Due to a lack of suitable tools, the genetic basis of this lifestyle and other unique features of Patescibacteira remain unexplored. Here, we show that Saccharibacteria exhibit natural competence, and we exploit this property for their genetic manipulation. Imaging of fluorescent protein-labeled Saccharibacteria provides high spatiotemporal resolution of phenomena accompanying epibiotic growth, and a transposon-insertion sequencing (Tn-seq) genome-wide screen reveals the contribution of enigmatic Saccharibacterial genes to growth on their hosts. Finally, we leverage metagenomic data to provide cutting-edge protein structure-based bioinformatic resources that support the strain Southlakia epibionticum and its corresponding host, Actinomyces israelii, as a model system for unlocking the molecular underpinnings of the epibiotic lifestyle.

Recent advances in predicting and modeling protein-protein interactions.

Protein-protein interactions (PPIs) drive biological processes, and disruption of PPIs can cause disease. With recent breakthroughs in structure prediction and a deluge of genomic sequence data, computational methods to predict PPIs and model spatial structures of protein complexes are now approaching the accuracy of experimental approaches for permanent interactions and show promise for elucidating transient interactions. As we describe here, the key to this success is rich evolutionary information deciphered from thousands of homologous sequences that coevolve in interacting partners. This covariation signal, revealed by sophisticated statistical and machine learning (ML) algorithms, predicts physiological interactions. Accurate artificial intelligence (AI)-based modeling of protein structures promises to provide accurate 3D models of PPIs at a proteome-wide scale.

Interleukin-6 signaling drives fibrosis in unresolved inflammation.

Fibrosis in response to tissue damage or persistent inflammation is a pathological hallmark of many chronic degenerative diseases. By using a model of acute peritoneal inflammation, we have examined how repeated inflammatory activation promotes fibrotic tissue injury. In this context, fibrosis was strictly dependent on interleukin-6 (IL-6). Repeat inflammation induced IL-6-mediated T helper 1 (Th1) cell effector commitment and the emergence of STAT1 (signal transducer and activator of transcription-1) activity within the peritoneal membrane. Fibrosis was not observed in mice lacking interferon-γ (IFN-γ), STAT1, or RAG-1. Here, IFN-γ and STAT1 signaling disrupted the turnover of extracellular matrix by metalloproteases. Whereas IL-6-deficient mice resisted fibrosis, transfer of polarized Th1 cells or inhibition of MMP activity reversed this outcome. Thus, IL-6 causes compromised tissue repair by shifting acute inflammation into a more chronic profibrotic state through induction of Th1 cell responses as a consequence of recurrent inflammation.

Mechanically Ventilated Patients Shed High-Titer Live Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) for Extended Periods From Both the Upper and Lower Respiratory Tract.

BACKGROUND: SARS-CoV-2 infection can lead to severe acute respiratory distress syndrome needing intensive care admission and may lead to death. As a virus that transmits by respiratory droplets and aerosols, determining the duration of viable virus shedding from the respiratory tract is critical for patient prognosis, and informs infection-control measures both within healthcare settings and the public domain. METHODS: We prospectively examined upper and lower airway respiratory secretions for both viral RNA and infectious virions in mechanically ventilated patients admitted to the intensive care unit (ICU) of the University Hospital of Wales. Samples were taken from the oral cavity (saliva), oropharynx (subglottic aspirate), or lower respiratory tract (nondirected bronchoalveolar lavage [NBAL] or bronchoalveolar lavage [BAL]) and analyzed by both quantitative PCR (qPCR) and plaque assay. RESULTS: 117 samples were obtained from 25 patients. qPCR showed extremely high rates of positivity across all sample types; however, live virus was far more common in saliva (68%) than in BAL/NBAL (32%). Average titers of live virus were higher in subglottic aspirates (4.5 × 107) than in saliva (2.2 × 106) or BAL/NBAL (8.5 × 106) and reached >108 PFU/mL in some samples. The longest duration of shedding was 98 days, while most patients (14/25) shed live virus for ≥20 days. CONCLUSIONS: ICU patients infected with SARS-CoV-2 can shed high titers of virus both in the upper and lower respiratory tract and tend to be prolonged shedders. This information is important for decision making around cohorting patients, de-escalation of personal protective equipment, and undertaking potential aerosol-generating procedures.

IFITM3-specific antibody reveals IFN preferences and slow IFN induction of the antiviral factor IFITM3 in humans.

Using a specific antibody, we found that expression of the viral restriction factor IFITM3 differs across cell types within the immune compartment with higher expression in myeloid rather than lymphoid cells. IFITM3 expression was increased following IFN stimulation, mostly type I, in immune cells, with the exception of T cells.

The Marine-Derived Macrolactone Mandelalide A Is an Indirect Activator of AMPK.

The mandelalides are complex macrolactone natural products with distinct macrocycle motifs and a bioactivity profile that is heavily influenced by compound glycosylation. Mandelalides A and B are direct inhibitors of mitochondrial ATP synthase (complex V) and therefore more toxic to mammalian cells with an oxidative metabolic phenotype. To provide further insight into the pharmacology of the mandelalides, we studied the AMP-activated protein kinase (AMPK) energy stress pathway and report that mandelalide A is an indirect activator of AMPK. Wild-type mouse embryonic fibroblasts (MEFs) and representative human non-small cell lung cancer (NSCLC) cells showed statistically significant increases in phospho-AMPK (Thr172) and phospho-ACC (Ser79) in response to mandelalide A. Mandelalide L, which also harbors an A-type macrocycle, induced similar increases in phospho-AMPK (Thr172) and phospho-ACC (Ser79) in U87-MG glioblastoma cells. In contrast, MEFs co-treated with an AMPK inhibitor (dorsomorphin), AMPKα-null MEFs, or NSCLC cells lacking liver kinase B1 (LKB1) lacked this activity. Mandelalide A was significantly more cytotoxic to AMPKα-null MEFs than wild-type cells, suggesting that AMPK activation serves as a protective response to mandelalide-induced depletion of cellular ATP. However, LKB1 status alone was not predictive of the antiproliferative effects of mandelalide A against NSCLC cells. When EGFR status was considered, erlotinib and mandelalide A showed strong cytotoxic synergy in combination against erlotinib-resistant 11-18 NSCLC cells but not against erlotinib-sensitive PC-9 cells. Finally, prolonged exposures rendered mandelalide A, a potent and efficacious cytotoxin, against a panel of human glioblastoma cell types regardless of the underlying metabolic phenotype of the cell. These results add biological relevance to the mandelalide series and provide the basis for their further pre-clinical evaluation as ATP synthase inhibitors and secondary activators of AMPK.

Initial Presentation of Granulomatosis with Polyangiitis as Progressive Skull Base Osteomyelitis.

A healthy man in his 30s presented with a 2-week history of severe bitemporal pain and pressure. He was initially treated for presumed acute rhinosinusitis, but his symptoms continued to worsen and underwent endoscopic sinus surgery at an outside community facility. He developed left abducens nerve palsy postoperatively, and magnetic resonance imaging (MRI) demonstrated evidence of extensive skull base osteomyelitis. He was initiated on intravenous (IV) broad-spectrum antibiotics but was subsequently found to have prostatic and submandibular sterile fluid collections. The patient subsequently developed new right abducens and left vagal nerve palsies and underwent revision endoscopic sinus surgery. Pathology revealed extensive inflammation, necrotizing granulomas, and evidence of small and medium vessel vasculitis. Extensive laboratory workup was negative, except for anti-PR-3 antibody positivity. Given the characteristic findings on pathology and laboratory findings, the patient was diagnosed with granulomatosis with polyangiitis (GPA). High-dose glucocorticoid therapy as well as rituximab infusion were promptly initiated. He had marked improvement in his symptoms and resolution of his right CN VI palsy but left-sided CN VI and CN X palsies persisted. This patient presented without the typical rhinologic manifestations of GPA, and rather presented with progressive sinusitis, skull base osteomyelitis with associated cranial neuropathies, and aseptic systemic abscesses. Prompt diagnosis of GPA is particularly important in those with otorhinolaryngological manifestations, as early initial immunosuppressive therapy has been linked to lower relapse and mortality rates. Vigilance and early differentiation between GPA and other forms of sinusitis is of critical importance, particularly when symptoms are refractory to standard rhinosinusitis therapies.

Protein oligomer modeling guided by predicted interchain contacts in CASP14.

For CASP14, we developed deep learning-based methods for predicting homo-oligomeric and hetero-oligomeric contacts and used them for oligomer modeling. To build structure models, we developed an oligomer structure generation method that utilizes predicted interchain contacts to guide iterative restrained minimization from random backbone structures. We supplemented this gradient-based fold-and-dock method with template-based and ab initio docking approaches using deep learning-based subunit predictions on 29 assembly targets. These methods produced oligomer models with summed Z-scores 5.5 units higher than the next best group, with the fold-and-dock method having the best relative performance. Over the eight targets for which this method was used, the best of the five submitted models had average oligomer TM-score of 0.71 (average oligomer TM-score of the next best group: 0.64), and explicit modeling of inter-subunit interactions improved modeling of six out of 40 individual domains (ΔGDT-TS > 2.0).

Protein tertiary structure prediction and refinement using deep learning and Rosetta in CASP14.

The trRosetta structure prediction method employs deep learning to generate predicted residue-residue distance and orientation distributions from which 3D models are built. We sought to improve the method by incorporating as inputs (in addition to sequence information) both language model embeddings and template information weighted by sequence similarity to the target. We also developed a refinement pipeline that recombines models generated by template-free and template utilizing versions of trRosetta guided by the DeepAccNet accuracy predictor. Both benchmark tests and CASP results show that the new pipeline is a considerable improvement over the original trRosetta, and it is faster and requires less computing resources, completing the entire modeling process in a median < 3 h in CASP14. Our human group improved results with this pipeline primarily by identifying additional homologous sequences for input into the network. We also used the DeepAccNet accuracy predictor to guide Rosetta high-resolution refinement for submissions in the regular and refinement categories; although performance was quite good on a CASP relative scale, the overall improvements were rather modest in part due to missing inter-domain or inter-chain contacts.

Optimal CD8+ T-cell memory formation following subcutaneous cytomegalovirus infection requires virus replication but not early dendritic cell responses.

Cytomegalovirus (CMV) induction of large frequencies of highly functional memory T cells has attracted much interest in the utility of CMV-based vaccine vectors, with exciting preclinical data obtained in models of infectious diseases and cancer. However, pathogenesis of human CMV (HCMV) remains a concern. Attenuated CMV-based vectors, such as replication- or spread-deficient viruses, potentially offer an alternative to fully replicating vectors. However, it is not well understood how CMV attenuation impacts vector immunogenicity, particularly when administered via relevant routes of immunization such as the skin. Herein, we used the murine cytomegalovirus (MCMV) model to investigate the impact of vector attenuation on T-cell memory formation following subcutaneous administration. We found that the spread-deficient virus (ΔgL-MCMV) was impaired in its ability to induce memory CD8+ T cells reactive to some (M38, IE1) but not all (IE3) viral antigens. Impaired-memory T-cell development was associated with a preferential and pronounced loss of polyfunctional (IFN-γ+ TNF-α+ ) T cells and also reduced accumulation of TCF1+ T cells, and was not rescued by increasing the dose of replication-defective MCMV. Finally, whilst vector attenuation reduced dendritic cell (DC) recruitment to skin-draining lymph nodes, systematic depletion of multiple DC subsets during acute subcutaneous MCMV infection had a negligible impact on T-cell memory formation, implying that attenuated responses induced by replication-deficient vectors were likely not a consequence of impaired initial DC activation. Thus, overall, these data imply that the choice of antigen and/or cloning strategy of exogenous antigen in combination with the route of immunization may influence the ability of attenuated CMV vectors to induce robust functional T-cell memory.

Burden of nosocomial COVID-19 in Wales: results from a multicentre retrospective observational study of 2508 hospitalised adults.

The burden of nosocomial SARS-CoV-2 infection remains poorly defined. We report on the outcomes of 2508 adults with molecularly-confirmed SARS-CoV-2 admitted across 18 major hospitals, representing over 60% of those hospitalised across Wales between 1 March and 1 July 2020. Inpatient mortality for nosocomial infection ranged from 38% to 42%, consistently higher than participants with community-acquired infection (31%-35%) across a range of case definitions. Those with hospital-acquired infection were older and frailer than those infected within the community. Nosocomial diagnosis occurred a median of 30 days following admission (IQR 21-63), suggesting a window for prophylactic or postexposure interventions, alongside enhanced infection control measures.

IRF5 Promotes Influenza Virus-Induced Inflammatory Responses in Human Induced Pluripotent Stem Cell-Derived Myeloid Cells and Murine Models.

Recognition of influenza A virus (IAV) by the innate immune system triggers pathways that restrict viral replication, activate innate immune cells, and regulate adaptive immunity. However, excessive innate immune activation can exaggerate disease. The pathways promoting excessive activation are incompletely understood, with limited experimental models to investigate the mechanisms driving influenza virus-induced inflammation in humans. Interferon regulatory factor 5 (IRF5) is a transcription factor that plays important roles in the induction of cytokines after viral sensing. In an in vivo model of IAV infection, IRF5 deficiency reduced IAV-driven immune pathology and associated inflammatory cytokine production, specifically reducing cytokine-producing myeloid cell populations in Irf5-/- mice but not impacting type 1 interferon (IFN) production or virus replication. Using cytometry by time of flight (CyTOF), we identified that human lung IRF5 expression was highest in cells of the myeloid lineage. To investigate the role of IRF5 in mediating human inflammatory responses by myeloid cells to IAV, we employed human-induced pluripotent stem cells (hIPSCs) with biallelic mutations in IRF5, demonstrating for the first time that induced pluripotent stem cell-derived dendritic cells (iPS-DCs) with biallelic mutations can be used to investigate the regulation of human virus-induced immune responses. Using this technology, we reveal that IRF5 deficiency in human DCs, or macrophages, corresponded with reduced virus-induced inflammatory cytokine production, with IRF5 acting downstream of Toll-like receptor 7 (TLR7) and, possibly, retinoic acid-inducible gene I (RIG-I) after viral sensing. Thus, IRF5 acts as a regulator of myeloid cell inflammatory cytokine production during IAV infection in mice and humans and drives immune-mediated viral pathogenesis independently of type 1 IFN and virus replication.IMPORTANCE The inflammatory response to influenza A virus (IAV) participates in infection control but contributes to disease severity. After viral detection, intracellular pathways are activated, initiating cytokine production, but these pathways are incompletely understood. We show that interferon regulatory factor 5 (IRF5) mediates IAV-induced inflammation and, in mice, drives pathology. This was independent of antiviral type 1 IFN and virus replication, implying that IRF5 could be specifically targeted to treat influenza virus-induced inflammation. We show for the first time that human iPSC technology can be exploited in genetic studies of virus-induced immune responses. Using this technology, we deleted IRF5 in human myeloid cells. These IRF5-deficient cells exhibited impaired influenza virus-induced cytokine production and revealed that IRF5 acts downstream of Toll-like receptor 7 and possibly retinoic acid-inducible gene I. Our data demonstrate the importance of IRF5 in influenza virus-induced inflammation, suggesting that genetic variation in the IRF5 gene may influence host susceptibility to viral diseases.

The protective effect of inflammatory monocytes during systemic C. albicans infection is dependent on collaboration between C-type lectin-like receptors.

Invasive candidiasis, mainly caused by Candida albicans, is a serious healthcare problem with high mortality rates, particularly in immunocompromised patients. Innate immune cells express pathogen recognition receptors (PRRs) including C-type lectin-like receptors (CLRs) that bind C. albicans to initiate an immune response. Multiple CLRs including Dectin-1, Dectin-2 and Mincle have been proposed individually to contribute to the immune response to C. albicans. However how these receptors collaborate to clear a fungal infection is unknown. Herein, we used novel multi-CLR knockout (KO) mice to decipher the individual, collaborative and collective roles of Dectin-1, Dectin-2 and Mincle during systemic C. albicans infection. These studies revealed an unappreciated and profound role for CLR co-operation in anti-fungal immunity. The protective effect of multiple CLRs was markedly greater than any single receptor, and was mediated through inflammatory monocytes via recognition and phagocytosis of C. albicans, and production of C. albicans-induced cytokines and chemokines. These CLRs were dispensable for mediating similar responses from neutrophils, likely due to lower expression of these CLRs on neutrophils compared to inflammatory monocytes. Concurrent deletion of Dectin-1 and Dectin-2, or all three CLRs, resulted in dramatically increased susceptibility to systemic C. albicans infection compared to mice lacking a single CLR. Multi-CLR KO mice were unable to control fungal growth due to an inadequate early inflammatory monocyte-mediated response. In response to excessive fungal growth, the multi-CLR KO mice mounted a hyper-inflammatory response, likely leading to multiple organ failure. Thus, these data reveal a critical role for CLR co-operation in the effective control of C. albicans and maintenance of organ function during infection.

IL-33 Augments Virus-Specific Memory T Cell Inflation and Potentiates the Efficacy of an Attenuated Cytomegalovirus-Based Vaccine.

Candidate vaccines designed to generate T cell-based immunity are typically vectored by nonpersistent viruses, which largely fail to elicit durable effector memory T cell responses. This limitation can be overcome using recombinant strains of CMV. Proof-of-principle studies have demonstrated the potential benefits of this approach, most notably in the SIV model, but safety concerns require the development of nonreplicating alternatives with comparable immunogenicity. In this study, we show that IL-33 promotes the accumulation and recall kinetics of circulating and tissue-resident memory T cells in mice infected with murine CMV. Using a replication-deficient murine CMV vector, we further show that exogenous IL-33 boosts vaccine-induced memory T cell responses, which protect against subsequent heterologous viral challenge. These data suggest that IL-33 could serve as a useful adjuvant to improve the efficacy of vaccines based on attenuated derivatives of CMV.

Manuka honey versus saline sinus irrigation in the treatment of cystic fibrosis-associated chronic rhinosinusitis: A randomised pilot trial.

OBJECTIVES: Manuka honey attacks biofilms, which contribute to bacterial persistence in cystic fibrosis sinusitis. The primary objective was to determine feasibility of investigating manuka honey as an irrigation treatment for cystic fibrosis sinusitis and secondarily to assess the treatment's preliminary effectiveness. DESIGN: Prospective, single-blinded (clinician only), randomised, parallel two-arm pilot trial. SETTING: Tertiary rhinology clinic. PARTICIPANTS: Subjects had recalcitrant cystic fibrosis sinusitis and previous sinus surgery. They received manuka honey or saline sinus irrigations twice daily for 30 days. MAIN OUTCOME MEASURES: Main outcomes were recruitment/retention rates and tolerability. Preliminary effectiveness was assessed based on quality-of-life Sinonasal Outcome Test-22 and Lund-Kennedy endoscopic change scores and post-treatment culture negativity. RESULTS: Over 10 months, 13 subjects were enrolled, and 77% (10/13) were included in the analysis. Manuka honey irrigations were well-tolerated. The quality-of-life change score was clinically significant for manuka honey (-9 [-14,-6]) but not saline (-5 [-9,-1]), although the difference was not statistically significant (P = .29). Lund-Kennedy endoscopic change score was significantly better for manuka honey (-3 [-5,-3]) versus saline (0 [0,0]) (P = .006). There was no difference in post-treatment culture negativity between manuka honey (1/5, 20%) and saline (0/5, 0%) (P = 1.00). CONCLUSIONS: Manuka honey irrigations were well tolerated, and retention rates were high. Preliminary data showed that manuka honey achieved a clinically important difference in quality-of-life score and a significantly better endoscopic outcome. Microbiological control was difficult to achieve. A future definitive trial would require multi-institutional recruitment.

Histone chaperone HIRA deposits histone H3.3 onto foreign viral DNA and contributes to anti-viral intrinsic immunity.

The HIRA histone chaperone complex deposits histone H3.3 into nucleosomes in a DNA replication- and sequence-independent manner. As herpesvirus genomes enter the nucleus as naked DNA, we asked whether the HIRA chaperone complex affects herpesvirus infection. After infection of primary cells with HSV or CMV, or transient transfection with naked plasmid DNA, HIRA re-localizes to PML bodies, sites of cellular anti-viral activity. HIRA co-localizes with viral genomes, binds to incoming viral and plasmid DNAs and deposits histone H3.3 onto these. Anti-viral interferons (IFN) specifically induce HIRA/PML co-localization at PML nuclear bodies and HIRA recruitment to IFN target genes, although HIRA is not required for IFN-inducible expression of these genes. HIRA is, however, required for suppression of viral gene expression, virus replication and lytic infection and restricts murine CMV replication in vivo. We propose that the HIRA chaperone complex represses incoming naked viral DNAs through chromatinization as part of intrinsic cellular immunity.

Novel viral vectors in infectious diseases.

Since the development of vaccinia virus as a vaccine vector in 1984, the utility of numerous viruses in vaccination strategies has been explored. In recent years, key improvements to existing vectors such as those based on adenovirus have led to significant improvements in immunogenicity and efficacy. Furthermore, exciting new vectors that exploit viruses such as cytomegalovirus (CMV) and vesicular stomatitis virus (VSV) have emerged. Herein, we summarize these recent developments in viral vector technologies, focusing on novel vectors based on CMV, VSV, measles and modified adenovirus. We discuss the potential utility of these exciting approaches in eliciting protection against infectious diseases.

Violation of the 12/23 rule of genomic V(D)J recombination is common in lymphocytes.

V(D)J genomic recombination joins single gene segments to encode an extensive repertoire of antigen receptor specificities in T and B lymphocytes. This process initiates with double-stranded breaks adjacent to conserved recombination signal sequences that contain either 12- or 23-nucleotide spacer regions. Only recombination between signal sequences with unequal spacers results in productive coding genes, a phenomenon known as the "12/23 rule." Here we present two novel genomic tools that allow the capture and analysis of immune locus rearrangements from whole thymic and splenic tissues using second-generation sequencing. Further, we provide strong evidence that the 12/23 rule of genomic recombination is frequently violated under physiological conditions, resulting in unanticipated hybrid recombinations in ∼10% of Tcra excision circles. Hence, we demonstrate that strict adherence to the 12/23 rule is intrinsic neither to recombination signal sequences nor to the catalytic process of recombination and propose that nonclassical excision circles are liberated during the formation of antigen receptor diversity.

Cytomegalovirus-Specific IL-10-Producing CD4+ T Cells Are Governed by Type-I IFN-Induced IL-27 and Promote Virus Persistence.

CD4+ T cells support host defence against herpesviruses and other viral pathogens. We identified that CD4+ T cells from systemic and mucosal tissues of hosts infected with the ß-herpesviridae human cytomegalovirus (HCMV) or murine cytomegalovirus (MCMV) express the regulatory cytokine interleukin (IL)-10. IL-10+CD4+ T cells co-expressed TH1-associated transcription factors and chemokine receptors. Mice lacking T cell-derived IL-10 elicited enhanced antiviral T cell responses and restricted MCMV persistence in salivary glands and secretion in saliva. Thus, IL-10+CD4+ T cells suppress antiviral immune responses against CMV. Expansion of this T-cell population in the periphery was promoted by IL-27 whereas mucosal IL-10+ T cell responses were ICOS-dependent. Infected Il27rα-deficient mice with reduced peripheral IL-10+CD4+ T cell accumulation displayed robust T cell responses and restricted MCMV persistence and shedding. Temporal inhibition experiments revealed that IL-27R signaling during initial infection was required for the suppression of T cell immunity and control of virus shedding during MCMV persistence. IL-27 production was promoted by type-I IFN, suggesting that ß-herpesviridae exploit the immune-regulatory properties of this antiviral pathway to establish chronicity. Further, our data reveal that cytokine signaling events during initial infection profoundly influence virus chronicity.

IL-27 Induced by Select Candida spp. via TLR7/NOD2 Signaling and IFN-ß Production Inhibits Fungal Clearance.

Candida spp. elicit cytokine production downstream of various pathogen recognition receptors, including C-type lectin-like receptors, TLRs, and nucleotide oligomerization domain (NOD)-like receptors. IL-12 family members IL-12p70 and IL-23 are important for host immunity against Candida spp. In this article, we show that IL-27, another IL-12 family member, is produced by myeloid cells in response to selected Candida spp. We demonstrate a novel mechanism for Candida parapsilosis-mediated induction of IL-27 in a TLR7-, MyD88-, and NOD2-dependent manner. Our data revealed that IFN-ß is induced by C. parapsilosis, which in turn signals through the IFN-α/ß receptor and STAT1/2 to induce IL-27. Moreover, IL-27R (WSX-1)-deficient mice systemically infected with C. parapsilosis displayed enhanced pathogen clearance compared with wild-type mice. This was associated with increased levels of proinflammatory cytokines in the serum and increased IFN-γ and IL-17 responses in the spleens of IL-27R-deficient mice. Thus, our data define a novel link between C. parapsilosis, TLR7, NOD2, IFN-ß, and IL-27, and we have identified an important role for IL-27 in the immune response against C. parapsilosis Overall, these findings demonstrate an important mechanism for the suppression of protective immune responses during infection with C. parapsilosis, which has potential relevance for infections with other fungal pathogens.