IFN-λ Research Articles

Decidual production of interferon lambda in response to ZIKV persistence: Clinical evidence and in vitro modelling

Zika virus (ZIKV) infections during pregnancy can result in Congenital Zika Syndrome (CZS), a range of severe neurological outcomes in fetuses that primarily occur during early gestational stages possibly due to placental damage. Although some placentas can maintain ZIKV persistence for weeks or months after the initial infection and diagnosis, the impact of this viral persistence is still unknown. Here, we aimed to investigate the immunological repercussion of ZIKV persistence in term placentas. As such, term placentas from 64 pregnant women diagnosed with Zika in different gestational periods were analyzed by ZIKV RT-qPCR, examination of decidua and placental villous histopathology, and expression of inflammation-related genes and IFNL1-4. Subsequently, we explored primary cultures of term decidual Extravillous Trophoblasts (EVTs) and Term Chorionic Villi (TCV) explants, as in vitro models to access the immunological consequences of placental ZIKV infection. Placenta from CZS cases presented low IFNL1-4 expression, evidencing the critical protective role of theses cytokines in the clinical outcome. Term placentas cleared for ZIKV showed increased levels of IFNL1, 3, and 4, whether viral persistence was related with a proinflammatory profile. Conversely, upon ZIKV persistence placentas with decidual inflammation showed high IFNL1-4 levels. In vitro experiments showed that term EVTs are more permissive, and secreted higher levels of IFN-α2 and IFN-λ1 compared to TCV explants. The results suggest that, upon ZIKV persistence, the maternal-skewed decidua contributes to placental inflammatory and antiviral signature, through chronic deciduitis and IFNL upregulation. Although further studies are needed to elucidate the mechanisms underlying the decidual responses against ZIKV. Hence, this study presents unique insights and valuable in vitro models for evaluating the immunological landscape of placentas upon ZIKV persistence.

Antiviral activity of adenoviral vector expressing human interferon lambda-4 against influenza virus.

Interferon lambda (IFNλ), classified as a type III IFN, is a representative cytokine that plays an important role in innate immunity along with type I IFN. IFNλ can elicit antiviral states by inducing peculiar sets of IFN-stimulated genes (ISGs). In this study, an adenoviral vector expression system with a tetracycline operator system was used to express human IFNλ4 in cells and mice. The formation of recombinant adenovirus (rAd-huIFNλ4) was confirmed using immunohistochemistry assays and transmission electron microscopy. Its purity was verified by quantifying host cell DNA and host cell proteins, as well as by confirming the absence of the replication-competent adenovirus. The transduction of rAd-huIFNλ4 induced ISGs and inhibited four subtypes of the influenza virus in both mouse-derived (LA-4) and human-derived cells (A549). The antiviral state was confirmed in BALB/c mice following intranasal inoculation with 109 PFU of rAd-huIFNλ4, which led to the inhibition of four subtypes of the influenza virus in mouse lungs, with reduced inflammatory lesions. These results imply that human IFNλ4 could induce antiviral status by modulating ISG expression in mice.

Treatment outcome and germline predictive factors of ropeginterferon alpha-2b in myeloproliferative neoplasm patients.

Studies have shown that some single nucleotide polymorphisms (SNPs) could serve as excellent markers in foretelling the treatment outcome of interferon (IFN) in myeloproliferative neoplasms (MPN). However, most work originated from western countries, and data from different ethnic populations have been lacking. To gain insights, targeted sequencing was performed to detect myeloid-associated mutations and SNPs in eight loci across three genes (IFNL4, IFN-γ, and inosine triphosphate pyrophosphatase [ITPA]) to explore their predictive roles in our cohort of 21 ropeginterferon alpha-2b (ROPEG)-treated MPN patients, among whom real-time quantitative PCR was also performed periodically to monitor the JAK2V617F allele burden in 19 JAK2V617F-mutated cases. ELN response criteria were adopted to designate patients as good responders if they achieved complete hematological responses (CHR) within 1 year (CHR1) or attained major molecular responses (MMR), which occurred in 70% and 45% of the patients, respectively. IFNL4 and IFN-γ gene SNPs were infrequent in our population and were thus excluded from further analysis. Two ITPA SNPs rs6051702 A>C and rs1127354 C>A were associated with an inferior CHR1 rate and MMR rate, respectively. The former seemed to be linked to grade 2 or worse hepatotoxicity as well, although the comparison was of borderline significance only (50%, vs. 6.7% in those with common haplotype, p = 0.053). Twelve patients harbored 19 additional somatic mutations in 12 genes, but the trajectory of these mutations varied considerably and was not predictive of any response. Overall, this study provided valuable information on the ethnics- and genetics-based algorithm in the treatment of MPN.

Early interferon lambda production is induced by double-stranded RNA in iPS-derived hepatocyte-like cells.

Hepatotropic viruses are amongst the most ubiquitous pathogens worldwide, causing significant morbidity and mortality. As hepatocytes are among the primary targets of these viruses, their ability to mount early effective innate defence responses is of major research interest. Interferon lambda (IFNL) is produced early in response to viral stimulation in other cell types, but hepatocyte production of this interferon is little investigated. Due to the difficulty and significant costs in obtaining and culturing human primary hepatocytes, surrogate systems are widely sought. Here we used induced pluripotent stem (iPS)-derived hepatocyte-like cells (HLCs) to investigate hepatic IFNL expression in response to viral-like ligands. We demonstrate that hepatocytes rely on cytoplasmic pattern recognition receptors (PRRs) such as Protein Kinase RNA-dependent (PKR) and retinoic acid-inducible gene-I (RIG-I)-like receptors (RLR) for the detection of double stranded RNA. Stimulation of HLCs by viral-like RNA ligands activating cytosolic RNA sensors resulted in thousand fold increase of type III interferon gene expression. These results are in contrast with type I IFN expression, which was induced to a lower extent. Concomitant induction of interferon stimulated genes, such as interferon-stimulated gene 15 (ISG15) and CXCL10, indicated the ability of HLCs to activate interferon-dependent activity. These results demonstrate that HLCs mount an innate antiviral response upon stimulation with viral-like RNA characterized by the induction of type III IFN.

Interferon Lambda: An Anonymous Warrior of Host-Microbial Fray in The Pathogenesis of Periodontal Diseases

The current body of research focuses primarily on three fundamental groups of interferons: alpha, beta, and gamma interferons. However, little attention is paid to another important group of interferons called lambda interferons (IFN-λs), which have demonstrated activity against periodontal pathogens, particularly viruses. These recently discovered interferon-lambdas provide a striking contrast to the periodontal pathogens, exerting impact both at the capacity of the immune system and the cell, thereby affecting a variety of inflammatory and response pathways. Thus, this review sheds light on role of interferon lambda in the development of periodontal disease and associated activities. In order to collect the information necessary for this review, an exhaustive search of the relevant literature was conducted. The review focused on the structure, regulatory mechanisms, and role of interferon lambda in medical and periodontal infections and diseases. The findings of our review indicated that IFN-λs have an effect on the immunological regulatory mechanisms of the host in relation to viruses, bacteria, fungi, and parasites; nevertheless, their primary role is antiviral, and they have little to no effect on the immune system's ability to fight bacteria. Bangladesh Journal of Medical Science Vol.23 (Special Issue) 2024 p.S73-S78

Interferon lambda in respiratory viral infection: immunomodulatory functions and antiviral effects in epithelium.

Type III interferon (IFN-λ), a new member of the IFN family, was initially considered to possess antiviral functions similar to those of type I interferon, both of which are induced via the JAK/STAT pathway. Nevertheless, recent findings demonstrated that IFN-λ exerts a nonredundant antiviral function at the mucosal surface, preferentially produced in epithelial cells in contrast to type I interferon, and its function cannot be replaced by type I interferon. This review summarizes recent studies showing that IFN-λ inhibits the spread of viruses from the cell surface to the body. Further studies have found that the role of IFN-λ is not only limited to the abovementioned functions, but it can also can exert direct and/or indirect effects on immune cells in virus-induced inflammation. This review focuses on the antiviral activity of IFN-λ in the mucosal epithelial cells and its action on immune cells and summarizes the pathways by which IFN-λ exerts its action and differentiates it from other interferons in terms of mechanism. Finally, we conclude that IFN-λ is a potent epidermal antiviral factor that enhances the respiratory mucosal immune response and has excellent therapeutic potential in combating respiratory viral infections.

Interferon lambda restricts herpes simplex virus skin disease by suppressing neutrophil-mediated pathology.

Type III interferons (IFN-λ) are antiviral and immunomodulatory cytokines that have been best characterized in respiratory and gastrointestinal infections, but the effects of IFN-λ against skin infections have not been extensively investigated. We sought to define the skin-specific effects of IFN-λ against the highly prevalent human pathogen, herpes simplex virus (HSV). We infected mice lacking the IFN-λ receptor (Ifnlr1-/-), both the IFN-λ and the IFN-α/β receptors (Ifnar1-/-Ifnlr1-/-), or IFN-λ cytokines (Ifnl2/3-/-) and found that IFN-λ restricts the severity of HSV-1 and HSV-2 skin lesions without affecting viral loads. We used RNAseq to define IFN-λ- and IFN-β-induced transcriptional responses in primary mouse keratinocytes. Using conditional knockout mice, we found that IFN-λ signaling in both keratinocytes and neutrophils was necessary to control HSV-1 skin lesion severity and that IFN-λ signaling in keratinocytes suppressed CXCL9-mediated neutrophil recruitment to the skin. Furthermore, depleting neutrophils or blocking CXCL9 protected against severe HSV-1 skin lesions in Ifnlr1-/- mice. Altogether, our results suggest that IFN-λ plays an immunomodulatory role in the skin that restricts neutrophil-mediated pathology during HSV infection and suggests potential applications for IFN-λ in treating viral skin infections.IMPORTANCEType III interferons (IFN-λ) have been shown to have antiviral and immunomodulatory effects at epithelial barriers such as the respiratory and gastrointestinal tracts, but their effects on the skin have not been extensively investigated. We used mice lacking IFN-λ signaling to investigate the skin-specific effects of IFN-λ against the herpes simplex virus (HSV), which targets epithelial tissues to cause cold sores and genital herpes. We found that IFN-λ limited the severity of HSV skin lesions without affecting viral load and that this protective effect required IFN-λ signaling in both keratinocytes and neutrophils. We found that IFN-λ signaling in keratinocytes suppressed neutrophil recruitment to the skin and that depleting neutrophils protected against severe HSV skin lesions in the absence of IFN-λ. Altogether, our results suggest that IFN-λ plays an immunomodulatory role in the skin that restricts neutrophil-mediated pathology during HSV infection and suggests potential applications for IFN-λ in treating viral skin infections.

Crystallization and biochemical studies of the NYN domain of human KHNYN.

KHNYN is composed of an N-terminal KH-like RNA-binding domain and a C-terminal PIN/NYN endoribonuclease domain. It forms a complex with zinc-finger antiviral protein (ZAP), leading to the degradation of viral or cellular RNAs depending on the ZAP isoform. Here, the production, crystallization andbiochemical analysis of the NYN domain (residues 477-636) of human KHNYN are presented. The NYN domain was crystallized with a heptameric single-stranded RNA from the AU-rich elements of the 3'-UTR of interferon lambda 3. The crystal belonged to space group P4132, with unit-cell parameters a= b = c = 111.3 Å, and diffacted to 1.72 Å resolution. The RNase activity of the NYN domain was demonstrated using different single-stranded RNAs, together with the binding between the NYN domain of KHNYN and the zinc-finger domain of ZAP.

Association of IFNL3 gene rs4803217 with spontaneous clearance of Hepatitis C virus in patients from West Mexico

Association of IFNL3 gene rs4803217 with spontaneous clearance of Hepatitis C virus in patients from West Mexico

Effect of interferon lambda on the generation of active oxygen species in mice under conditions of oxidative stress induced by Mitomycin C

This research was aimed at studying the effect of species-specific recombinant bovine interferon lambda (IFN-λ) on the generation of reactive oxygen species (ROS) in mouse liver and bone marrow cells under conditions of mitomycin Cinduced oxidative stress. The experiment included female white laboratory mice. There were formed four groups of 6 animals each: the negative control group (group I); the group of mice that received a three-fold injection of IFN-λ at a dose of 0.1 ml/kg (group II) and mice that, in addition to IFN-λ, were administered a cytotoxic drug that induced free radical oxidation processes - mitomycin C at a dose of 10 mg/kg (group III), as well as the animals receiving only mitomycin C (group IV). We studied the concentration and viability of a cell suspension obtained from the liver of mice, as well as the relative content of intracellular ROS in the liver and bone marrow cells of animals, assessed by the fluorescence intensity of the oxidized form of 2',7'-dichlorodihydrofluorescein diacetate. The concentration and viability of cells in the liver suspension of healthy mice did not change with the introduction of IFN-λ (group II), indicating the absence of a toxic effect of IFN-λ on these cells. An increase in the level of ROS in the studied cells was detected when IFN-λ was administered to mice of group II (an increase in the level of ROS by 1.3 times in liver cells and by 2.9 times in bone marrow cells, relative to the mice of group I) and a decrease in the level of ROS in the mice under conditions of oxidative stress induced by mitomycin C (reduction in the content of intracellular ROS by 1.9 and 7.2 times in liver and bone marrow cells in the animals of group III, relative to the mice of group IV). The presented changes may indicate the normalization of IFN-λ redox balance in the body and, probably, appear in connection with the immunomodulatory activity of IFN-λ.

IFN-λ3 is induced by Leishmania donovani and can inhibit parasite growth in cell line models but not in the mouse model, while it shows a significant association with leishmaniasis in humans.

The intracellular protozoan parasite Leishmania donovani causes debilitating human diseases that involve visceral and dermal manifestations. Type 3 interferons (IFNs), also referred to as lambda IFNs (IFNL, IFN-L, or IFN-λ), are known to play protective roles against intracellular pathogens at the epithelial surfaces. Herein, we show that L. donovani induces IFN-λ3 in human as well as mouse cell line-derived macrophages. Interestingly, IFN-λ3 treatment significantly decreased parasite load in infected cells, mainly by increasing reactive oxygen species production. Microscopic examination showed that IFN-λ3 inhibited uptake but not replication, while the phagocytic ability of the cells was not affected. This was confirmed by experiments that showed that IFN-λ3 could decrease parasite load only when added to the medium at earlier time points, either during or soon after parasite uptake, but had no effect on parasite load when added at 24 h post-infection, suggesting that an early event during parasite uptake was targeted. Furthermore, the parasites could overcome the inhibitory effect of IFN-λ3, which was added at earlier time points, within 2-3 days post-infection. BALB/c mice treated with IFN-λ3 before infection led to a significant increase in expression of IL-4 and ARG1 post-infection in the spleen and liver, respectively, and to different pathological changes, especially in the liver, but not to changes in parasite load. Treatment with IFN-λ3 during infection did not decrease the parasite load in the spleen either. However, IFN-λ3 was significantly increased in the sera of visceral leishmaniasis patients, and the IFNL genetic variant rs12979860 was significantly associated with susceptibility to leishmaniasis.

Molecular genetic association of rs8099917 and rs1800795 polymorphisms in the progression of hepatitis Delta virus liver disease.

The relationship between viral infections and host factors holds high hopes for identifying the role of Interferon Lambda 3 (IFNL3) and Interleukin 6 (IL-6) polymorphisms in the development of Chronic Liver Disease (CLD) in patients infected with hepatitis Delta virus (HDV) in the Western Brazilian Amazon. Cross-sectional study conducted with a cohort of 40 chronic HDV patients, 27 with CLD and 13 without evident liver damage. Biological samples from the participants were analyzed using the polymerase chain reaction (PCR) technique, followed by sequencing by the automated Sanger method. The rs8099917 T allele, from the IFNL3 gene, showed a higher frequency in both groups; however, it was not possible to establish an association with HDV infection [OR = 1.42 (0.42 - 4.75; p = 0.556 (95% CI). For IL-6, the rs1800795 G allele was superior to rs1800795 C. Analyzing both distributions in the studied groups, any association with HDV was absent (p > 0.05). The results suggest that the rs8099917 T/G (IFNL3) and rs1800795 G/C (IL-6) polymorphisms are not associated with the evolution of HDV in the studied population.

Antiviral activity of bovine type III interferon against bovine viral diarrhea virus is greatly reduced in bovine turbinate cells due to limited expression of IFN lambda receptor 1 (IL-28Rα).

The antiviral activity of recombinant bovine interferon lambda 3 (bovIFN-λ3) against bovine viral diarrhea virus (BVDV) has been demonstrated in vitro in Madin-Darby bovine kidney cells (MDBK) and in vivo in cattle. However, anti-BVDV activity of bovIFN-λ3 has not been studied in bovine respiratory tract epithelial cells, supposedly a primary target of BVDV infection when entering the host by the oronasal route. Here we investigated the anti-BVDV activity of bovIFN-λ3 in bovine turbinate-derived primary epithelial cells (BTu) using BVDV infection and immunoperoxidase staining, TCID50, RT-qPCR, DNA and transcriptome sequencing, and transfection with plasmids containing the two subunits, IL-28Rα and IL-10Rβ that constitute the bovIFN-λ3 receptor. Our immunoperoxidase staining, RT-qPCR, and TCID50 results show that while BVDV was successfully cleared in MDBK cells treated with bovIFN-λ3 and bovIFN-α, only the latter, bovIFN-α, cleared BVDV in BTu cells. Preincubation of MDBK cells with bovIFN-λ3 before BVDV infection was needed to induce optimal antiviral state. Both cell types displayed intact type I and III IFN signaling pathways and expressed similar levels of IL-10Rβ subunit of the type III IFN receptor. Sequencing of PCR amplicon of the IL-28Rα subunit revealed intact transmembrane domain and lack of single nucleotide polymorphisms (SNPs) in BTu cells. However, RT-qPCR and transcriptomic analyses showed a lower expression of IL-28Rα transcripts in BTu cells as compared to MDBK cells. Interestingly, transfection of BTu cells with a plasmid encoding IL-28Rα subunit, but not IL-10Rβ subunit, established the bovIFN-λ3 sensitivity showing similar anti-BVDV activity to the response in MDBK cells. Our results demonstrate that the sensitivity of cells to bovIFN-λ3 depends not only on the quality but also of the quantity of the IL-28Rα subunit of the heterodimeric receptor. A reduction in IL-28Rα transcript expression was detected in BTu as compared to MDBK cells, despite the absence of spliced variants or SNPs. The establishment of bovIFN-λ3 induced anti-BVDV activity in BTu cells transfected with an IL-28Rα plasmid suggests that the level of expression of this receptor subunit is crucial for the specific antiviral activity of type III IFN in these cells.

Predictive Potential Of Il28b Gene In Hcv Patients, Resistant To Daclatasvir And Sofosbuvir In KPK Population.

Recently various combinations of direct acting antivirals (DAAs) have been tried successfully. The Sofosbuvir + Daclatasvir combination has been used with promising results. Recently, resistance has been noticed against DAAs. Therefore, polymorphism at particular sites in the interleukin 28B gene are under study to find possible association with resistance. This study was aimed at finding out any association of SNPs rs8099917 and rs12979860 (IL28B gene) with response and resistance to treatment in HCV genotype 3 patients in Khyber Pakhtunkhwa. This cross sectional, Analytical study was conducted at Gastroenterology/hepatology OPD of Prime Teaching Hospital, Peshawar Medical College. Collected Samples were stored at -20o C in PCR Lab of the College. DNA extraction and genotyping was carried out at BJ Molecular Biology Lab in Rawalpindi. Data was analyzed by using SPSS version 21. Chi-Square Test was used to see the statistically significant differences between rs8099917 T/G and rs12979860 T/C model. In the IL28-B gene, single nucleotide polymorphism at rs12979860 T/C model, we observed that there are 37.5% CC homozygous, 12.5% TT homozygous and 50% CT heterozygous genotypes in resistant patients and 42.85% CC homozygous, 28.57% TT and 28.57% CT genotype in responder group. In rs12979860 T/C model, genotype of IL28-B in the responder and resistant group significantly varies at p-value =0.00572. We conclude that in SNP at rs12979860, CC genotype is associated with clearance of HCV, while CT genotype was more prevalent in the resistant group and associated with chronicity.

Architectonics of parenchymal organs of white rats under conditions of induced immunosuppression and the use of Interferon lambda

Violation of the functioning of the organs of the immune system, both in humans and in animals, is due to the influence of unfavorable factors of natural and anthropogenic origin on the body, as well as infectious diseases of various etiologies. The article discusses changes in the architectonics of parenchymal organs of white laboratory rats after exposure to the drug interferon lambda on the background of cyclophosphamide (CF). It was found that modeling of immunosuppression through the use of CF led to a decrease in the number of lymphoid cells and the appearance of foci of accumulation of blast cells and megakaryocytes, which indicates a lesion of lymphoid and hematopoietic tissues. In addition, an immunosuppressive effect on the spleen was revealed, the mass coefficient of which in the group with the use of CF was increased 3.53 times, in the group with the simultaneous use of CF and the drug interferon lambda – 2.75 times relative to the control group. There was also a decrease in the mass coefficient of the thymus by 47.6-50.0% in the same groups, which can be regarded as damage to the organs of the immune system. The negative effect of CF on the spleen was confirmed by histological examination. Thus, when inducing immunosuppression, the loss of white pulp was 73.0-77.5% relative to the group of control animals, which is 20.0% higher than in rats treated with interferon lambda, which may indicate a positive immunotropic effect of the drug under study. In addition, no significant morphological changes were detected when the body of healthy rats was exposed to interferon lambda in the studied organs, the morphological picture is similar to that of intact animals, which may indicate the safety of its use to animals.

Interferon lambda receptor-1 isoforms differentially influence gene expression and HBV replication in stem cell-derived hepatocytes

BackgroundIn the tolerogenic liver, inadequate or ineffective interferon signaling fails to clear chronic HBV infection. Lambda IFNs (IFNL) bind the interferon lambda receptor-1 (IFNLR1) which dimerizes with IL10RB to induce transcription of antiviral interferon-stimulated genes (ISG). IFNLR1 is expressed on hepatocytes, but low expression may limit the strength and antiviral efficacy of IFNL signaling. Three IFNLR1 transcriptional variants are detected in hepatocytes whose role in regulation of IFNL signaling is unclear: a full-length and signaling-capable form (isoform 1), a form that lacks a portion of the intracellular JAK1 binding domain (isoform 2), and a secreted form (isoform 3), the latter two predicted to be signaling defective. We hypothesized that altering expression of IFNLR1 isoforms would differentially impact the hepatocellular response to IFNLs and HBV replication. MethodsInduced pluripotent stem-cell derived hepatocytes (iHeps) engineered to contain FLAG-tagged, doxycycline-inducible IFNLR1 isoform constructs were HBV-infected then treated with IFNL3 followed by assessment of gene expression, HBV replication, and cellular viability. ResultsMinimal overexpression of IFNLR1 isoform 1 markedly augmented ISG expression, induced de novo proinflammatory gene expression, and enhanced inhibition of HBV replication after IFNL treatment without adversely affecting cell viability. In contrast, overexpression of IFNLR1 isoform 2 or 3 partially augmented IFNL-induced ISG expression but did not support proinflammatory gene expression and minimally impacted HBV replication. ConclusionsIFNLR1 isoforms differentially influence IFNL-induced gene expression and HBV replication in hepatocytes. Regulated IFNLR1 expression in vivo could limit the capacity of this pathway to counteract HBV replication.

Identification and characterization of the anti-viral interferon lambda 3 as direct target of the Epstein-Barr virus microRNA-BART7-3p

ABSTRACT The human Epstein–Barr virus (EBV), as a member of the human γ herpes viruses (HHV), is known to be linked with distinct tumor types. It is a double-stranded DNA virus and its genome encodes among others for 48 different microRNAs (miRs). Current research demonstrated a strong involvement of certain EBV-miRs in molecular immune evasion mechanisms of infected cells by, e.g., the disruption of human leukocyte antigen (HLA) class Ia and NKG2D functions. To determine novel targets of EBV-miRs involved in immune surveillance, ebv-miR-BART7-3p, an EBV-encoded miR with high expression levels during the different lytic and latent EBV life cycle phases, was overexpressed in human HEK293T cells. Using a cDNA microarray-based comparative analysis, 234 (229 downregulated and 5 upregulated) deregulated human transcripts were identified in ebv-miR-BART7-3p transfectants, which were mainly involved in cellular processes and molecular binding. A statistically significant downregulation of the anti-proliferative and tumor-suppressive hsa-miR-34A and the anti-viral interferon lambda (IFNL)3 mRNA was found. The ebv-miR-BART7-3p-mediated downregulation of IFNL3 expression was due to a direct interaction with the IFNL3 3’-untranslated region (UTR) as determined by luciferase reporter gene assays including the identification of the accurate ebv-miR-BART7-3p binding site. The effect of ebv-miR-BART7-3p on the IFNL3 expression was validated both in human cell lines in vitro and in human tissue specimen with known EBV status. These results expand the current knowledge of EBV-encoded miRs and their role in immune evasion, pathogenesis and malignant transformation.

1346. Genetic Variation at the Interferon λ Locus and Association with Clinical Outcome and Severity of COVID-19

Abstract Background People with obesity are at increased risk of severe COVID-19, with host inflammation a key contributor. Interferon (IFN) lambda 4 (IFNλ4) is a type III IFN expressed in individuals with the rs368234815-ΔG single nucleotide polymorphism (SNP) which is implicated in host immune responses to viral infections. We explored associations of this SNP to host inflammation, body mass index (BMI) and COVID-19 disease severity. Methods Individuals with SARS-CoV-2, enrolled in the All-Ireland Infectious Diseases Cohort were genotyped for the rs368234815 SNP by allelic discrimination assay, and plasma circulating type I, II and III IFNs by immunoassay that were measured in a sub-cohort collected within ten days of symptom onset. We compared the prevalence of COVID-19 mild cases according to WHO criteria between IFNλ4 non-expressing (TT) and expressing (ΔG) genotypes using a Kruskal Wallis test. IFNλ4 polymorphisms affecting type I, II and III IFNs were assessed in the sub-cohort using a stepwise binary logistic regression adjusted for age, sex at birth, ethnicity, and comorbidities, including obesity (BMI ≥ 30 kg/m2). Results 853 participants were enrolled, of whom 471 (55%) harboured IFNλ4-TT/TT (Table 1). Expression of IFNλ4-ΔG was not significantly different between disease severity groups (P = 0.357). Within the early sampling sub-cohort (n = 321), we observed higher circulating IFNλ1 and IFNλ2 in those with more severe COVID-19 compared to mild disease (P < 0.01) (Fig 1). Only IFNλ2 remained significantly associated with mild COVID-19 in adjusted analyses (B COEFF 0.232 (0.067, 0.808), P = 0.021). We found no consistent associations between IFNλ4 genotypes and circulating interferons. Furthermore, we observed significantly higher IFNλ2 in people with obesity. However, the relationship between elevated plasma IFNλ2 and disease severity was only observed in people without obesity (P < 0.01) but not in those with obesity (Fig 2). Table 1 Clinicodemographic Details of Enrolled Patients in the AIID COVID-19 Cohort Figure 1 Plasma Circulating Levels (pg/mL) of Type I (IFN-α2a, and IFN-β), Type II (IFN-γ), and Type III (IFN-λ 1, IFN-λ 2 IL28A, IFN-λ 3 IL28B) Interferons. (A) World Health Organisation (WHO) COVID-19 disease severity criteria association with plasma circulating levels of type I, II, and III interferons. (B) Assessment of IFN-λ 4 expressing (ΔG) and non-expressing (TT) genotypes effects on circulating levels of type I, II, and III interferons. Ln - natural log; ns P > 0.05, * P ≤ 0.05, ** P ≤ 0.01, *** P ≤ 0.001. Figure 2 World Health Organisation (WHO) COVID-19 Disease Severity Association with Circulating Plasma Levels of Type III (IFN-λ 2 IL28A) Interferon and Obesity Status. Obesity defined as BMI ≥ 30 Kg/m2. Ln - natural log; ns P > 0.05, * P ≤ 0.05, ** P ≤ 0.01. Conclusion IFNλ4 genotypes were not associated with COVID-19 disease severity or levels of circulating interferons. However, IFNλ2 was higher in individuals with obesity, though associations between IFNλ2 and disease severity was lost, suggesting that obesity may contribute to increased risk of severe COVID-19 through increased expression of IFNλ2. Disclosures All Authors: No reported disclosures

Variants of IFNL4 Gene in Amazonian and Northern Brazilian Populations.

Since the discovery of the polymorphic nature of the IFNL4 gene, its variants have been investigated and associated with several viral diseases, with an emphasis on hepatitis C. However, the impacts of these variants on mixed-race and native populations in the northern region of Brazil are scarce. We investigated three variants of the IFNL4 gene in populations from this location, which were among the 14 most frequent variants in worldwide populations, and compared the frequencies obtained to populational data from the 1000 Genomes Project, gnomAD and ABraOM databases. Our results demonstrate that mixed-race and native populations from the northern region of Brazil present frequencies like those of European and Asian groups for the rs74597329 and rs11322783 variants, and like all populations presented for the rs4803221 variant. These data reinforce the role of world populations in shaping the genetic profile of Brazilian populations, indicate patterns of illness according to the expressed genotype, and infer an individual predisposition to certain diseases.

Abstract 18007: Role of Interferon Lambda in Influenza-Induced Exacerbation of Atherosclerosis

Introduction and Hypothesis: Influenza infection is a significant public health and economic threat around the world. Although pneumonia is the most common complication associated with influenza, there are several clinical reports demonstrating increased risk for cardiovascular disease. In influenza infection type I, type II and type III IFNs play an indispensable role in controlling the virus. In atherosclerosis, type I and type II IFNs promote atherosclerosis by inducing chemokines from macrophages and vascular endothelial cells. Studies have shown that the influenza infection exacerbates atherosclerosis. However, there are no studies determining the role of type III IFNs on influenza-induced exacerbation of atherosclerosis. In this study, we hypothesize that the type III IFN (IFNL3) may play a protective role in atherosclerosis. Methods: ApoE -/- mice were fed with a high-fat diet (HFD) containing 42% Kcal fat (Teklad) for 11 weeks. Mice were then infected with influenza A/PR/8/34 (H1N1) (100 pfu) and treated with recombinant IFNL3 by oropharyngeal (O/P) aspiration or intraperitoneal (I/P) injection, and weight loss, and gene expression of inflammatory cytokines and chemokines were measured. In another study, HFD-fed ApoE -/- and ApoE -/- IFNLR1 -/- mice were infected with influenza, and the disease outcomes were measured as described above. Results and Conclusions: IFNL3 treatment decreased influenza-induced weight loss in ApoE -/- mice during the early phase (4-6 days) of influenza infection. Further, IFNL3 treatment decreased gene expression levels of IL-6 and CCL2 in the aorta in influenza-infected ApoE -/- mice. Based on these findings, it seems likely that INFL3 plays a protective role in acute influenza-induced exacerbation of atherosclerosis. However, ApoE -/- IFNLR1 -/- mice recovered body weight faster than wild-type mice suggesting a detrimental role for IFNL after acute infection. These data show that IFNLR plays a protective role during the early phase of influenza infection and potentially a pathological role during the recovery phase of influenza infection.