Interferon Induction Research Articles

Theilovirus 3C Protease Cleaves the C-Terminal Domain of the Innate Immune RNA Sensor, Melanoma Differentiation-Associated Gene 5, and Impairs Double-Stranded RNA-Mediated IFN Response.

Melanoma differentiation-associated gene 5 (MDA5), a member of the retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs), has pivotal roles in innate immune responses against many positive-stranded RNA viruses, including picornavirus and coronavirus. Upon engagement with dsRNA derived from viral infection, MDA5 initiates coordinated signal transduction leading to type I IFN induction to restrict viral replication. In this study, we describe a targeted cleavage events of MDA5 by the 3C protease from Theilovirus. Upon ectopic expression of theilovirus 3C protease from Saffold virus or Theiler's murine encephalomyelitis virus but not encephalomyocarditis virus, fragments of cleaved MDA5 were observed in a dose-dependent manner. When enzymatically inactive Theilovirus 3C protease was expressed, MDA5 cleavage was completely abrogated. Mass spectrometric analysis identified two cleavage sites at the C terminus of MDA5, cleaving off one of the RNA-binding domains. The same cleavage pattern was observed during Theilovirus infection. The cleavage of MDA5 by Theilovirus protease impaired ATP hydrolysis, RNA binding, and filament assembly on RNA, resulting in dysfunction of MDA5 as an innate immune RNA sensor for IFN induction. Furthermore, the cleavage-resistant MDA5 mutant against the 3C protease showed an enhanced IFN response during Saffold virus infection, indicating that Theilovirus has a strategy to circumvent the antiviral immune response by cleaving MDA5 using 3C protease. In summary, these data suggest MDA5 cleavage by 3C protease as a novel immune evasive strategy of Theilovirus.

Interferon alpha inducible protein 6 is a negative regulator of innate immune responses by modulating RIG-I activation.

Interferons (IFNs), IFN-stimulated genes (ISGs), and inflammatory cytokines mediate innate immune responses, and are essential to establish an antiviral response. Within the innate immune responses, retinoic acid-inducible gene I (RIG-I) is a key sensor of virus infections, mediating the transcriptional induction of IFNs and inflammatory proteins. Nevertheless, since excessive responses could be detrimental to the host, these responses need to be tightly regulated. In this work, we describe, for the first time, how knocking-down or knocking-out the expression of IFN alpha-inducible protein 6 (IFI6) increases IFN, ISG, and pro-inflammatory cytokine expression after the infections with Influenza A Virus (IAV), Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), and Sendai Virus (SeV), or poly(I:C) transfection. We also show how overexpression of IFI6 produces the opposite effect, in vitro and in vivo, indicating that IFI6 negatively modulates the induction of innate immune responses. Knocking-out or knocking-down the expression of IFI6 diminishes the production of infectious IAV and SARS-CoV-2, most likely because of its effect on antiviral responses. Importantly, we report a novel interaction of IFI6 with RIG-I, most likely mediated through binding to RNA, that affects RIG-I activation, providing a molecular mechanism for the effect of IFI6 on negatively regulating innate immunity. Remarkably, these new functions of IFI6 could be targeted to treat diseases associated with an exacerbated induction of innate immune responses and to combat viral infections, such as IAV and SARS-CoV-2.

Biochemical blood parameters of patients with aleutian mink disease under the influence of alloferon

Fur farming in Russia can be considered one of the most profitable industries. However, outbreaks of infectious diseases in animal farms, in the difficult conditions of the global financial crisis, cause irreparable economic damage, which negatively affects the prospects for the development of the industry. One of these diseases is the Aleutian Mink disease, which entails enormous losses associated with the lack of treatment and prevention. To date, the use of interferon inducers is considered a promising direction in the fight against viral diseases of animals. The objects of the study were mink of 30-day-old sapphire breed, spontaneously infected with the Aleutian disease virus. Two groups of 50 animals (25 females and 25 males) each were formed using the method of analog groups. The minks of the experimental group were subcutaneously injected with alloferon at a dose of 0.5 mg per head twice with an interval of 6 days. The control group animals were injected with saline solution (NaCl 0.9%) in the same dosing regimen. The biochemical parameters of blood were taken into account after 1 month of the experiment. Our studies have shown that in experimental animals the blood content of total protein was lower by 19.6%, globulins by 24.4%, urea levels were 2 times lower, creatinine values were 1.5 times, the amount of ALT and AST were 2.5 and 1.6 times lower, respectively. The obtained results of a biochemical study may indicate an improvement in metabolic processes in experimental individuals, which contributes to an increase in the productive qualities of sick animals. As a result of the conducted research, it can be concluded that it is advisable to use drugs based on alloferon for mink patients with viral plasmocytosis in order to reduce the economic damage from the Aleutian mink disease.

How Different Pathologies Are Affected by IFIT Expression.

The type-I interferon (IFN) system represents the first line of defense against viral pathogens. Recognition of the virus initiates complex signaling pathways that result in the transcriptional induction of IFNs, which are then secreted. Secreted IFNs stimulate nearby cells and result in the production of numerous proinflammatory cytokines and antiviral factors. Of particular note, IFN-induced tetratricopeptide repeat (IFIT) proteins have been thoroughly studied because of their antiviral activity against different viral pathogens. Although classically studied as an antiviral protein, IFIT expression has recently been investigated in the context of nonviral pathologies, such as cancer and sepsis. In oral squamous cell carcinoma (OSCC), IFIT1 and IFIT3 promote metastasis, while IFIT2 exhibits the opposite effect. The role of IFIT proteins during bacterial/fungal sepsis is still under investigation, with studies showing conflicting roles for IFIT2 in disease severity. In the setting of viral sepsis, IFIT proteins play a key role in clearing viral infection. As a result, many viral pathogens, such as SARS-CoV-2, employ mechanisms to inhibit the type-I IFN system and promote viral replication. In cancers that are characterized by upregulated IFIT proteins, medications that decrease IFIT expression may reduce metastasis and improve survival rates. Likewise, in cases of viral sepsis, therapeutics that increase IFIT expression may improve viral clearance and reduce the risk of septic shock. By understanding the effect of IFIT proteins in different pathologies, novel therapeutics can be developed to halt disease progression.

Radiotherapy enhances CXCR3highCD8+ T cell activation through inducing IFNγ-mediated CXCL10 and ICAM-1 expression in lung cancer cells

Radiotherapy (RT) not only damages tumors but also induces interferon (IFN) expression in tumors. IFNs mediate PD-L1 to exhaust CD8+ T cells, but which also directly impact tumor cells and potentially activate anti-tumor immune surveillance. Little is known about the contradictory mechanism of IFNs in regulating CD8+ T-mediated anti-tumor activity in lung cancer. This study found that RT induced IFNs and CXCL9/10 expression in the RT-treated lung cancer cells. Specifically, RT- and IFNγ-pretreated A549 significantly activated CD8+ T cells, resulting in significant inhibition of A549 colony formation. RNAseq and consequent qPCR results revealed that IFNγ induced PD-L1, CXCL10, and ICAM-1, whereas PD-L1 knockdown activated CD8+ T cells, but ICAM-1 knockdown diminished CD8+ T cell activation. We further demonstrated that CXCR3 and CXCL10 decreased in the CD8+ T cells and nonCD8+ PBMCs, respectively, in the patients with lung cancer that expressed lower reactivation as co-cultured with A549 cells. In addition, inhibitors targeting CXCR3 and LFA-1 in CD8+ T cells significantly diminished CD8+ T cell activation and splenocytes-mediated anti-LL/2shPdl1. In conclusion, we validated that RT suppressed lung cancer and overexpress PD-L1, CXCL10, and ICAM-1, which exhibited different roles in regulating CD8+ T cell activity. We propose that CXCR3highCD8+ T cells stimulated by CXCL10 exhibit anti-tumor immunity, possibly by enhancing T cells-tumor cells adhesion through CXCL10/CXCR3-activated LFA-1-ICAM-1 interaction, but CXCR3lowCD8+ T cells with low CXCL10 in patients with lung cancer were exhausted by PD-L1 dominantly. Therefore, RT potentially activates CD8+ T cells by inducing IFNs-mediated CXCL10 and ICAM-1 expression in tumors to enhance CD8+ T-tumor adhesion and recognition. This study clarified the possible mechanisms of RT and IFNs in regulating CD8+ T cell activation in lung cancer.

The interferon stimulated gene-encoded protein HELZ2 inhibits human LINE-1 retrotransposition and LINE-1 RNA-mediated type I interferon induction

Some interferon stimulated genes (ISGs) encode proteins that inhibit LINE-1 (L1) retrotransposition. Here, we use immunoprecipitation followed by liquid chromatography-tandem mass spectrometry to identify proteins that associate with the L1 ORF1-encoded protein (ORF1p) in ribonucleoprotein particles. Three ISG proteins that interact with ORF1p inhibit retrotransposition: HECT and RLD domain containing E3 ubiquitin-protein ligase 5 (HERC5); 2′−5′-oligoadenylate synthetase-like (OASL); and helicase with zinc finger 2 (HELZ2). HERC5 destabilizes ORF1p, but does not affect its cellular localization. OASL impairs ORF1p cytoplasmic foci formation. HELZ2 recognizes sequences and/or structures within the L1 5′UTR to reduce L1 RNA, ORF1p, and ORF1p cytoplasmic foci levels. Overexpression of WT or reverse transcriptase-deficient L1s lead to a modest induction of IFN-α expression, which is abrogated upon HELZ2 overexpression. Notably, IFN-α expression is enhanced upon overexpression of an ORF1p RNA binding mutant, suggesting ORF1p binding might protect L1 RNA from “triggering” IFN-α induction. Thus, ISG proteins can inhibit retrotransposition by different mechanisms.

Rabies virus P protein binds to TBK1 and interferes with the formation of innate immunity-related liquid condensates

Viruses must overcome the interferon-mediated antiviral response to replicate and propagate into their host. Rabies virus (RABV) phosphoprotein P is known to inhibit interferon induction. Here, using a global mass spectrometry approach, we show that RABV P binds to TBK1, a kinase located at the crossroads of many interferon induction pathways, resulting in innate immunity inhibition. Mutations of TBK1 phosphorylation sites abolish P binding. Importantly, we demonstrate that upon RABV infection or detection of dsRNA by innate immunity sensors, TBK1 and its adaptor proteins NAP1 and SINTBAD form dynamic cytoplasmic condensates that have liquid properties. These condensates can form larger aggregates having ring-like structures in which NAP1 and TBK1 exhibit locally restricted movement. P binding to TBK1 interferes with the formation of these structures. This work demonstrates that proteins of the signaling pathway leading to interferon induction transiently form liquid organelles that can be targeted by viruses.

Targeting Type I Interferon Induction and Signaling: How Zika Virus Escapes from Host Innate Immunity.

Zika virus (ZIKV) infection causes neurological disorders and draws great attention. ZIKV infection can elicit a wide range of immune response. Type I interferons (IFNs) as well as its signaling cascade play crucial role in innate immunity against ZIKV infection and in turn ZIKV can antagonize them. ZIKV genome are mainly recognized by Toll-like receptors 3 (TLR3), TLR7/8 and RIG-I-like receptor 1 (RIG-1), which induces the expression of Type I IFNs and interferon-stimulated genes (ISGs). ISGs exert antiviral activity at different stages of the ZIKV life cycle. On the other hand, ZIKV takes multiple strategies to antagonize the Type Ⅰ IFN induction and its signaling pathway to establish a pathogenic infection, especially by using the viral nonstructural (NS) proteins. Most of the NS proteins can directly interact with the factors in the pathways to escape the innate immunity. In addition, structural proteins also participate in the innate immune evasion and activation of antibody-binding of blood dendritic cell antigen 2 (BDCA2) or inflammasome also be used to enhance ZIKV replication. In this review, we summarize the recent findings about the interaction between ZIKV infection and type I IFNs pathways and suggest potential strategies for antiviral drug development.

Применение оксиэтиламмония метилфеноксиацетата для лечения острых респираторных вирусных инфекций на амбулаторном этапе

Aim: to analyze the clinical efficacy and safety of oxyethyl ammonium methyl phenoxy acetate for the outpatient treatment of acute respiratory viral infections (ARVI) in adults and adolescents. Patients and Methods: An observational, open-label, postregistration study was conducted. The study group included 122 patients (75 adults and 47 adolescents). All study group patients were prescribed with oxyethyl ammonium methyl phenoxy acetate (tablets) in addition to symptomatic therapy. Treatment course duration was 8 days. The comparison group included 50 patients (30 adults, historical control, and 20 adolescents) who received symptomatic therapy for ARVI only. A prospective-retrospective analysis of disease clinical course by studying medical records was performed. Results: on days 3–5 after starting therapy, the proportion of patients with severe ARVI symptoms and fever reduced by 42.0% in the study group adults and only by 10.0% in the comparison group adults (p=0.001). In the study group adults, fever reduced significantly faster (p≤0.05) than in the comparison group adults. On days 3–5 after starting therapy, asthenia persisted in 47.3% of study group adults and 70% of comparison group adults (p=0.002). In the study group adolescents, fever duration was 2.5 days less than in the comparison group adolescents (p ≤0.05). Only 10 study group adolescents (21.2%) still had asthenia on days 3–5 after starting therapy, which is 2.4 times less common than at baseline and 1.9 times less common than in comparison group adolescents. No ARVI complications that required continuation of treatment, involve other specialists, or the use of additional examinations and treatments were reported in both groups. Conclusion: in an outpatient setting, when a doctor needs to make a decision on complex therapy based only on clinical manifestations, the use of ethyl ammonium methyl phenoxy acetate is reasonable. KEYWORDS: ARVI, secondary immunodeficiency, interferon, adolescents, outpatient practice, oxyethyl ammonium methyl phenoxy acetate, adaptogen, interferon inducer, fever, asthenia. FOR CITATION: Esaulenko E.V., Novak K.E., Ibrokhimova A.D., Pozdnyakova M.G., Balashov A.L., Noginova E.Yu. Oxyethyl ammonium methyl phenoxy acetate for the outpatient treatment of acute respiratory viral infections. Russian Medical Inquiry. 2023;7(11):718–724 (in Russ.). DOI: 10.32364/2587-6821-2023-7-11-3.

Anti-G protein antibodies targeting the RSV G protein CX3C chemokine region improve the interferon response.

Respiratory syncytial virus (RSV) is a poor inducer of antiviral interferon (IFN) responses which result in incomplete immunity and RSV disease. Several RSV proteins alter antiviral responses, including the non-structural proteins (NS1, NS2) and the major viral surface proteins, that is, fusion (F) and attachment (G) proteins. The G protein modifies the host immune response to infection linked in part through a CX3 C chemokine motif. Anti-G protein monoclonal antibodies (mAbs), that is, clones 3D3 and 2D10 that target the G protein CX3C chemokine motif can neutralize RSV and inhibit G protein-CX3CR1 mediated chemotaxis. Determine how monoclonal antibodies against the RSV F and G proteins modify the type I and III IFN responses to RSV infection. As the G protein CX3 C motif is implicated in IFN antagonism, we evaluated two mAbs that block G protein CX3C-CX3CR1 interaction and compared responses to isotype mAb control using a functional cellular assay and mouse model. Mouse lung epithelial cells (MLE-15 cells) and BALB/c mice were infected with RSV Line19 F following prophylactic mAb treatment. Cell supernatant or bronchoalveolar lavage fluid (BALF) were assayed for types I and III IFNs. Cells were interrogated for changes in IFN-related gene expression. Treatment with an anti-G protein mAb (3D3) resulted in improved IFN responses compared with isotype control following infection with RSV, partially independently of neutralization, and this was linked to upregulated SOCS1 expression. These findings show that anti-G protein antibodies improve the protective early antiviral response, which has important implications for vaccine and therapeutic design. RSV is a leading cause of respiratory disease in infants and the elderly. The only Food and Drug Administration-approved prophylactic treatment is limited to an anti-F protein monoclonal antibody (mAb), that is, palivizumab which has modest efficacy against RSV disease. Accumulating evidence suggests that targeting the RSV attachment (G) protein may provide improved protection from RSV disease. It is known that the G protein is an IFN antagonist, and IFN has been shown to be protective against RSV disease. In this study, we compared IFN responses in mouse lung epithelial (MLE-15) cells and in mice infected with RSV Line19 F treated with anti-G protein or anti-F protein mAbs. The levels of type I and III IFNs were determined. Anti-G protein mAbs improved the levels of IFNs compared with isotype-treated controls. These findings support the concept that anti-G protein mAbs mediate improved IFN responses against RSV disease, which may enable improved treatment of RSV infections.

Armored modified vaccinia Ankara in cancer immunotherapy.

Cancer immunotherapy relies on unleashing the patient´s immune system against tumor cells. Cancer vaccines aim to stimulate both the innate and adaptive arms of immunity to achieve durable clinical responses. Some roadblocks for a successful cancer vaccine in the clinic include the tumor antigen of choice, the adjuvants employed to strengthen antitumor-specific immune responses, and the risks associated with enhancing immune-related adverse effects in patients. Modified vaccinia Ankara (MVA) belongs to the family of poxviruses and is a versatile vaccine platform that combines several attributes crucial for cancer therapy. First, MVA is an excellent inducer of innate immune responses leading to type I interferon secretion and induction of T helper cell type 1 (Th1) immune responses. Second, it elicits robust and durable humoral and cellular immunity against vector-encoded heterologous antigens. Third, MVA has enormous genomic flexibility, which allows for the expression of multiple antigenic and costimulatory entities. And fourth, its replication deficit in human cells ensures a excellent safety profile. In this review, we summarize the current understanding of how MVA induces innate and adaptive immune responses. Furthermore, we will give an overview of the tumor-associated antigens and immunomodulatory molecules that have been used to armor MVA and describe their clinical use. Finally, the route of MVA immunization and its impact on therapeutic efficacy depending on the immunomodulatory molecules expressed will be discussed.

Spring Viremia of Carp Virus N Protein Negatively Regulates IFN Induction through Autophagy-Lysosome-Dependent Degradation of STING.

Fish possess a powerful IFN system to defend against aquatic virus infections. Nevertheless, spring viremia of carp virus (SVCV) causes large-scale mortality in common carp and significant economic losses to aquaculture. Therefore, it is necessary to investigate the strategies used by SVCV to escape the IFN response. In this study, we show that the SVCV nucleoprotein (N protein) negatively regulates cellular IFN production by degrading stimulator of IFN genes (STING) via the autophagy-lysosome-dependent pathway. First, overexpression of N protein inhibited the IFN promoter activation induced by polyinosinic-polycytidylic acid and STING. Second, the N protein associated with STING and experiments using a dominant-negative STING mutant demonstrated that the N-terminal transmembrane domains of STING were indispensable for this interaction. Then, the N protein degraded STING in a dose-dependent and autophagy-lysosome-dependent manner. Intriguingly, in the absence of STING, individual N proteins could not elicit host autophagic flow. Furthermore, the autophagy factor Beclin1 was found to interact with the N protein to attenuate N protein-mediated STING degradation after beclin1 knockdown. Finally, the N protein remarkably weakened STING-enhanced cellular antiviral responses. These findings reveal that SVCV uses the host autophagic process to achieve immune escape, thus broadening our understanding of aquatic virus pathogenesis.

Scientific legacy of Professor A.A. Kasparov. Inductor of endogenous interferon Poludan in the treatment of ocular herpes and other corneal diseases

This article presents a retrospective analysis of the research findings by professor A.A. Kasparov, who developed and implemented a novel approach to treating ocular herpes. The treatment system is fundamentally different from the conventional chemotherapeutic approach and revolves around non-specific immunotherapy using an endogenous interferon inducer - a biosynthetic complex of polyriboadenylic and polyribouridylic acids, known as Poludan. This approach also incorporates personalized cell therapy based on Poludan, along with herpes vaccine aimed at preventing recurrence. The regenerative and antiviral properties of this approach have proven successful in treating other corneal conditions such as adenovirus infections, early postoperative bullous keratopathy, as well as in stimulation of epithelialization after refractive surgeries (photorefractive keratectomy, phototherapeutic keratectomy).

Study on Antiviral Activity and Pharmacological Safety of Double-Stranded Ribonucleic Acid for Intranasal Administration

Interferon inducers are of interest as the first line of defense against viral infections, including influenza. Double-stranded ribonucleic acid (dsRNA) for intranasal administration has been developed, the excipients and drug components were selected at the Institute of Medical Biotechnology, a branch of the State Research Center of Virology and Biotechnology «Vector». This work presents the results of the study on antiviral activity and pharmacological safety of a new form of dsRNA. The antiviral activity of the preparation was studied in BALB/c mice infected with influenza A/Aichi/2/68 (H3N2) or Bishkek/01/2009 (H1N1pdm09) viruses. A safety study was performed with a single administration of intranasal dsRNA into white outbred ICR mice. The study showed that the administration of therapeutic and prophylactic regimen of intranasal dsRNA at a dose of 2.5 mg/kg increases the survival and average life expectancy of mice infected with the mentioned strains of influenza virus. The protective effect of the preparation in mice infected with a lethal dose of Bishkek/01/2009 virus was comparable to the effect of Tamiflu. The absence of toxic effects of intranasal dsRNA at a pharmacological dose in laboratory mice, the functional state of their physiological systems, as well as main types of metabolism, established in the experiments, lead to a conclusion concerning pharmacological safety of the preparation and the prospects for further work to complete pharmaceutical development of a new antiviral drug.

NS2 is a key determinant of compatibility in reassortant avian influenza virus with heterologous H7N9-derived NS segment

Influenza A viruses are common pathogens with high prevalence worldwide and potential for pandemic spread. While influenza A infections typically elicit robust cellular innate immune responses, the non-structural protein 1 (NS1) antagonizes host anti-viral responses and is critical for efficient virus replication and virulence. The avian influenza virus (AIV) H7N9 initially emerged in China in 2013 and has since crossed the avian-human barrier, causing severe disease in humans. To investigate the influence of the H7N9 NS gene (NS079) on viral replication and innate immune response, we generated several recombinant AIVs bearing various NS079 segments on the backbone of H6N1 (strain 0702). Intriguingly, the recombinant virus bearing the heterologous NS079 gene was highly attenuated compared with virus carrying the homologous NS gene (NS0702). Furthermore, we generated a NS079-0702R virus that expresses a chimeric NS gene in which part of the NS079 effector domain was replaced with the sequence from NS0702. The NS079-0702R virus exhibited significantly enhanced viral yield, approximately 100-fold more than virus bearing NS079. The high infection rate of NS079-0702R virus was reflected by strong induction of IFN and Mx expression in human A549 cells. Intriguingly, our in vitro comparative analysis suggested that the increased NS079-0702R infection capacity was independent of the ability of NS1 to interact with cellular partners, such as PKR and CPSF30. Since partial substitution of the effector domain from NS0702 altered the coding sequence of NS2, we further generated another recombinant virus with NS2 derived from H7N9. Surprisingly, the virus with H7N9-derived NS2 exhibited growth characteristics similar to NS079. Our data demonstrate that swapping NS2 components changes infection efficiency, suggesting a key role for NS2 as a determinant of viral compatibility upon reassortment. These findings warrant further investigation into the precise mechanisms by which NS2 contributes to viral replication and host immunity.1

CURRENT ASPECTS OF ETIOTROPIC COVID-19 THERAPY

Since the beginning of the pandemic, repeated attempts have been made to develop etiotropic therapy for a novel coronavirus infection. Hydroxychloroquine, lopinavir/ritonavir, etc. derivatives were used as antiviral agents, however, they demonstrated a low efficiency and an insufficient safety. In this connection, other groups of drugs with a more effective and safe pharmacological profile are currently being actively used.The aimof the study was to analyze the literature references on the efficacy and safety of antiviral drugs for the COVID-19 treatment.Materials and methods.When searching for the materials for the review article writing, such abstract databases as PubMed, Google Scholar, e-Library were used. The search was carried out on publications for the period from January 2020 to september 2022. The key queries were: COVID-19, etiotropic therapy; immunological drugs; antiviral drugs; interferons.Results.Currently, there are various degrees of effective etiotropic drugs for the treatment of COVID-19 patients. The review has considered a few groups of drugs that are of interest from the point of view of etiotropic therapy: immunological drugs (anticovid plasma, the drugs based on antiviral antibodies, the drugs of recombinant interferons-α2 and -β1, as well as interferon inducers, i.e., the drugs based on double-stranded RNA sodium salt, and others); drugs that block the penetration of the virus into the cell (umifenovir); the drugs that disrupt the process of the viral replication (favipiravir, remdesivir, molnupiravir, nirmatrelvir/ritonavir).Conclusion.Synthetic antivirals, in particular favipiravir, molnupiravir, remdesivir, and nirmatrelvir/ritonavir, have the largest evidence base for their efficacy and safety. The search for new effective and safe etiotropic drugs for the treatment of COVID-19, as well as the collection and analysis of post-registration data on the drugs already used in clinical practice, continues.

Cytokine Receptor-Like Factor 3 Negatively Regulates Antiviral Immunity by Promoting the Degradation of TBK1 in Teleost Fish.

The cytokine receptor-like factor 3 (Crlf3) belongs to the orphan class I cytokine receptors and is identified as a neuroprotective erythropoietin receptor. In previous studies of Crlf3, few focused on its role in innate immunity. Therefore, this study explored the regulatory role of Crlf3 in innate immunity. TANK-binding kinase 1 (TBK1) is a vital adaptor protein for the activation of the RLRs-MVAS-IRF3 antiviral signaling axis; thus, its expression and activity must be tightly regulated to maintain immune homeostasis and avoid undesirable effects. Here, we report that Crlf3 is a negative regulator of type I interferon production. The expression of Crlf3 is induced by poly(I·C) or Siniperca chuatsi rhabdovirus (SCRV) treatment. Silencing of Crlf3 enhanced poly(I·C)- and SCRV-induced type I interferon production, whereas overexpression of Crlf3 suppressed type I interferon production. Mechanistically, Crlf3 interacted with TBK1 via its N domain and then inhibited type I interferon production by promoting TBK1 proteasomal degradation through K48-linked polyubiquitination. Our study shows that Crlf3 is a key factor for viral escape from innate antiviral immunity in fish and provides a new perspective on mammalian resistance to viral invasion. IMPORTANCE The expression of Crlf3 was upregulated with SCRV invasion, which proved that Crlf3 was involved in the regulation of the antiviral immune response. In this study, we found that the existence of Crlf3 promoted the replication of SCRV. Therefore, it is reasonable to believe that SCRV evades innate immune attack with the assistance of Crlf3. In addition, we report that Crlf3 negatively regulates interferon (IFN) induction by promoting the degradation of TBK1 in fish. We showed that Crlf3 is evenly distributed in the cytoplasm and interacts with TBK1. Further studies showed that Crlf3 specifically mediates K48-linked ubiquitination of TBK1 and promotes TBK1 degradation, resulting in a marked inhibition of retinoic acid-inducible gene I (RIG-I) downstream signaling.

Profiles and predictive value of cytokines in children with human metapneumovirus pneumonia.

Human metapneumovirus (HMPV) is an important cause of respiratory tract infections in young children. Early innate immune response to HMPV is focused on induction of antiviral interferons (IFNs) and other pro-inflammatory cytokines that are critical for the formation of adaptive immune responses. To evaluate the predictive value of Th1/Th2 cytokines which include IL-2, IL-4, IL-6, IL-10, INF-γ and TNF-α in pneumonia caused by HMPV. A retrospective study was performed among 59 pneumonia pediatric patients with HMPV infection and 33 healthy children as the control cohort, which was detected by the immunofluorescence assay, and the Th1/Th2 cytokines were measured by flow cytometry. 131 children infected with Influenza virus A (IVA) and 41 children infected with influenza virus B (IVB) were detected by RT-PCR assay in throat swabs. When compared with the healthy children, children who were infected with HMPV pneumonia had a significantly lower level of IL-2 (p < 0.001) and higher levels of IL-4 (p < 0.001), IL-6 (p = 0.001), IL-10 (p < 0.001), and IFN-γ (p < 0.001). Compared with patients diagnosed with IVA or IVB infection, HMPV-positive patients had significantly higher levels of IL-4 (p < 0.001 and < 0.001), IFN-γ (p < 0.001 and < 0.001), and TNF-α (p < 0.001 and 0.016). Moreover, compared with IVA patients, HMPV-positive patients had a significantly lower level of IL-6 (p = 0.033). Finally, when comparing cytokine levels among the patients with HMPV pneumonia, IL-6 and TNF-α levels were found to be significantly higher in the severe group than the mild group (p = 0.027 and 0.049). The IL-6 and TNF-α were used to differentiate between mild symptoms and severe symptoms in children diagnosed with HMPV pneumonia with an AUC of 0.678 (95% CI 0.526-0.829) and 0.658 (95% CI 0.506-0.809), respectively. Our study indicated that difference in cytokine trends depending on the virus species. The levels of IL-4, TNF-α and IFN-γ were significantly distinguished in children infected with HMPV versus IVA and IVB. IL-6 and TNF-α may be helpful in assessing the severity and prognosis of HMPV infection.

Marburg virus and the disease it causes

Over the 50 years since its discovery, many properties of the Marburg virus have been studied, but no reliable medical remedies of preventing and treating the infection it causes have been developed, although it can potentially cause large-scale epidemics.&#x0D; Marburg fever is relevant due to the risk of importation to other countries. The source of infection in nature is bats (reservoir) and monkeys (intermediate host), and the routes of transmission are aerosol, contact and alimentary. The mortality rate in recent outbreaks has reached 90%. In convalescents the causative agent was identified in tears, semen, and liver biopsies weeks and months after recovery.&#x0D; The lack of therapeutic and prophylactic antiviral drugs, high rates of mortality, infectivity, the ability of aerosol contamination, and a high epidemic potential all together define Marburg fever as a serious global threat to international health. The development of medical protection against this infection should be an urgent task of ensuring the biological safety of the population of the Russian Federation.&#x0D; The most promising ways to develop vaccines against Marburg fever are the construction of recombinants based on adenovirus, vesicular stomatitis virus or alphavirus replicon, DNA vaccines. A reliable protective effect of the chemotherapy drug remdesivir in combination with human antibodies, as well as an etiotropic drug with an antisense mechanism of action and an interferon inducer has been shown. In model experiments with pseudovirus, fundamentally new ways of developing pathogen inhibitors were found preventing its exit from cells, as well as the construction of anti-gene-binding Fab fragments that inhibit the synthesis of viral RNA.

U5 snRNP Core Proteins Are Key Components of the Defense Response against Viral Infection through Their Roles in Programmed Cell Death and Interferon Induction.

The spliceosome is a massive ribonucleoprotein structure composed of five small nuclear ribonucleoprotein (snRNP) complexes that catalyze the removal of introns from pre-mature RNA during constitutive and alternative splicing. EFTUD2, PRPF8, and SNRNP200 are core components of the U5 snRNP, which is crucial for spliceosome function as it coordinates and performs the last steps of the splicing reaction. Several studies have demonstrated U5 snRNP proteins as targeted during viral infection, with a limited understanding of their involvement in virus-host interactions. In the present study, we deciphered the respective impact of EFTUD2, PRPF8, and SNRNP200 on viral replication using mammalian reovirus as a model. Using a combination of RNA silencing, real-time cell analysis, cell death and viral replication assays, we discovered distinct and partially overlapping novel roles for EFTUD2, PRPF8, and SNRNP200 in cell survival, apoptosis, necroptosis, and the induction of the interferon response pathway. For instance, we demonstrated that EFTUD2 and SNRNP200 are required for both apoptosis and necroptosis, whereas EFTUD2 and PRPF8 are required for optimal interferon response against viral infection. Moreover, we demonstrated that EFTUD2 restricts viral replication, both in a single cycle and multiple cycles of viral replication. Altogether, these results establish U5 snRNP core components as key elements of the cellular antiviral response.