Interferon omega-1 is a protein that is encoded by the IFNW1 gene. [3] [4]
Interferon omega-1 (IFN-ω) is a subtype of the Interferon type I family. The Interferon Type 1 family is made up of cytokines (proteins used in cell signaling) which bind to the cell surface receptor IFNAR. They are found in mammals and play roles in immunoregulation, inflammation, T-cell response, and tumor cell identification. Type 1 Interferons have also been found in birds, lizards, and turtles. Multiple subvarients of IFN-ω have been observed in non-primate mammals with placentas. [5] [6] IFN-ω has been linked to antitumor activity and protection against bacterial and parasitic pathogens. [7]
Through genome sequence analysis, it’s thought that the IFN-ω gene diverged from the IFN-α gene roughly 130 million years ago. Interferon omega-1 serves as cytokines which promote innate immunity against viruses and cancers. They are involved with almost every nucleated cell. [7]
There are sixteen sub-types of Interferon type I. Despite having roughly 20%-60% sequence identity, the subtypes each act on IFNAR1 or IFNAR2 subunits of the class two helical cytokine receptor family. Specifically, IFN-ω shares 33% sequence similarity with IFN-β and 62% sequence similarity with IFN-α. [7] The IFNAR1 subunit contains an intracellular domain which is linked to Tyrosine kinase 2 and the IFNAR2 subunit contains an intracellular domain that is linked to Janus kinase 1. Once bound to these tyrosine kinases a [phosphorylation] cascade will progress and is regulated by the STAT protein. Different responses result from the binding of each type I Interferon and evidence points to the cause being conformational differences in ligand-receptor binding. The receptor can bind each type I Interferon in unique ways, creating respective downstream effects for each variant. [8]
As of writing, limited IFN-ω structures are publicly available. There has been a structure of the IFNω-IFNAR ternary complex which has been solved to a resolution of 3.5 angstroms via X-ray crystallography. [8] From this structure, the protein consists of four long and aligned alpha helices and one short alpha helix connection. It is bound to both subunits simultaneously and with each active site being at opposite ends of the protein. In this structure there is a small molecule of NAG bound to IFNAR1 on the opposite side of IFN-ω binding. [8]
The Arg35 residue in IFN-ω is one which binds to the IFNAR2 subunit and is conserved across most IFN type I subvarients. Leu32 of IFN-ω is another conserved residue in the hydrophobic cluster involved in IFNAR2 binding. The Val80 residue of IFNAR2 has shown to be key in discriminating between Type 1 Interferon subtypes and has a large effect on IFN-ω binding. [8]
For binding with the IFNAR1 subunit, the residue Phe67 of IFN-ω has key hydrophobic and aromatic interactions with the Leu134 residue of IFNAR1. Additional hotspot residues include Arg123 of IFN-ω and Tyr70 or the IFNAR1 subunit. A salt bridge is formed between Lys152 and Glu149 of IFN-ω and in a small distance from Glu77 of IFNAR1. When bound to IFN-ω, the SD1 of IFNAR1 undergoes a major conformational change that is not seen when unbound or bound to IFN-α2. [8]
A study reported correlation between a decreased level of Interferon type I proteins and more severe COVID-19 cases that are not associated with detectable autoantibodies against IFN-ω or IFN-α. [9]
IFN-ω has been licensed in several countries to treat canine parvovirus, feline leukemia virus, and feline immunodeficiency virus infections. However, due to expense and a time-consuming protocol of 15 total rounds of subcutaneous administration, its use remains limited. In guinea pigs, it has been found to significantly reduce viral loads of Influenza A virus subtype H1N1 upon daily treatment. A limiting factor in its therapeutic use is the recombinant protein’s short half-life, and this can potentially be worked around with techniques such as PEGylation. [7]
Although it hasn’t been licensed for therapeutic use, IFN-ω has been found to decrease the viral load of Enterovirus E, infectious bovine rhinotracheitis virus, Bovine viral diarrhea, Indiana vesiculovirus, pseudorabies virus, European bat lyssavirus, influenza virus, feline calicivirus, and feline herpesvirus-1 (FHV-1). However, further studies are needed to reinforce these claims. [7]
In combination with ribavirin, IFN-α has been used to treat chronic hepatitis C virus infections, however, this treatment option can carry extreme side effects. Evidence has emerged that IFN-ω could also serve as a potential treatment for HCV as it is more potent than IFN-α in repressing HCV RNA replicons. [7]
Although limitations include time-consumption, necessary facilities, lack of specificity, and use of radioisotopes, IFN-ω can be used in the detection of APS-1. Anti-IFN-ω antibodies are shown to develop before APS-1 symptoms show which allow for early detection of the virus. Methods of antibody detection include immunoassay, radioligand binding assay, and antiviral neutralization assays. [7]
Studies have also shown IFN-ω to treat numerous diseases in felines and canines, however, further studies are needed with larger sample sizes and controlled groups to ensure accuracy of results. There is also evidence of antitumor effects on human tumor xenografts in nude mice. [10]
Interferons are a group of signaling proteins made and released by host cells in response to the presence of several viruses. In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten their anti-viral defenses.
Interferon gamma is a dimerized soluble cytokine that is the only member of the type II class of interferons. The existence of this interferon, which early in its history was known as immune interferon, was described by E. F. Wheelock as a product of human leukocytes stimulated with phytohemagglutinin, and by others as a product of antigen-stimulated lymphocytes. It was also shown to be produced in human lymphocytes. or tuberculin-sensitized mouse peritoneal lymphocytes challenged with Mantoux test (PPD); the resulting supernatants were shown to inhibit growth of vesicular stomatitis virus. Those reports also contained the basic observation underlying the now widely employed interferon gamma release assay used to test for tuberculosis. In humans, the IFNG protein is encoded by the IFNG gene.
Interferon tau is a Type I interferon made of a single chain of amino acids. IFN-τ was first discovered in ruminants as the signal for the maternal recognition of pregnancy and originally named ovine trophoblast protein-1 (oTP-1). It has many physiological functions in the mammalian uterus, and also has anti-inflammatory effect that aids in the protection of the semi-allogeneic conceptus trophectoderm from the maternal immune system.
Interleukin-29 (IL-29) is a cytokine and it belongs to type III interferons group, also termed interferons λ (IFN-λ). IL-29 plays an important role in the immune response against pathogenes and especially against viruses by mechanisms similar to type I interferons, but targeting primarily cells of epithelial origin and hepatocytes.
The type-I interferons (IFN) are cytokines which play essential roles in inflammation, immunoregulation, tumor cells recognition, and T-cell responses. In the human genome, a cluster of thirteen functional IFN genes is located at the 9p21.3 cytoband over approximately 400 kb including coding genes for IFNα, IFNω (IFNW1), IFNɛ (IFNE), IFNк (IFNK) and IFNβ (IFNB1), plus 11 IFN pseudogenes.
The type III interferon group is a group of anti-viral cytokines, that consists of four IFN-λ (lambda) molecules called IFN-λ1, IFN-λ2, IFN-λ3, and IFN-λ4. They were discovered in 2003. Their function is similar to that of type I interferons, but is less intense and serves mostly as a first-line defense against viruses in the epithelium.
The interferon-α/β receptor (IFNAR) is a virtually ubiquitous membrane receptor which binds endogenous type I interferon (IFN) cytokines. Endogenous human type I IFNs include many subtypes, such as interferons-α, -β, -ε, -κ, -ω, and -ζ.
Non-receptor tyrosine-protein kinase TYK2 is an enzyme that in humans is encoded by the TYK2 gene.
Signal transducer and activator of transcription 4 (STAT4) is a transcription factor belonging to the STAT protein family, composed of STAT1, STAT2, STAT3, STAT4, STAT5A, STAT5B, STAT6. STAT proteins are key activators of gene transcription which bind to DNA in response to cytokine gradient. STAT proteins are a common part of Janus kinase (JAK)- signalling pathways, activated by cytokines.STAT4 is required for the development of Th1 cells from naive CD4+ T cells and IFN-γ production in response to IL-12. There are two known STAT4 transcripts, STAT4α and STAT4β, differing in the levels of interferon-gamma production downstream.
Signal transducer and activator of transcription 2 is a protein that in humans is encoded by the STAT2 gene. It is a member of the STAT protein family. This protein is critical to the biological response of type I interferons (IFNs). It functions as a transcription factor downstream of type I interferons. STAT2 sequence identity between mouse and human is only 68%.
Interferon-stimulated gene 15 (ISG15) is a 17 kDa secreted protein that in humans is encoded by the ISG15 gene. ISG15 is induced by type I interferon (IFN) and serves many functions, acting both as an extracellular cytokine and an intracellular protein modifier. The precise functions are diverse and vary among species but include potentiation of Interferon gamma (IFN-II) production in lymphocytes, ubiquitin-like conjugation to newly-synthesized proteins and negative regulation of the IFN-I response.
Interferon-alpha/beta receptor beta chain is a protein that in humans is encoded by the IFNAR2 gene.
Interferon alpha-1 is a protein that in humans is encoded by the IFNA1 gene.
Interferon alpha-2 is a protein that in humans is encoded by the IFNA2 gene.
Interferon regulatory factor 8 (IRF8) also known as interferon consensus sequence-binding protein (ICSBP), is a protein that in humans is encoded by the IRF8 gene. IRF8 is a transcription factor that plays critical roles in the regulation of lineage commitment and in myeloid cell maturation including the decision for a common myeloid progenitor (CMP) to differentiate into a monocyte precursor cell.
Interleukin 10 receptor, beta subunit is a subunit for the interleukin-10 receptor. IL10RB is its human gene.
Interleukin-28 receptor is a type II cytokine receptor found largely in epithelial cells. It binds type 3 interferons, interleukin-28 A, Interleukin-28B, interleukin 29 and interferon lambda 4. It consists of an α chain and shares a common β subunit with the interleukin-10 receptor. Binding to the interleukin-28 receptor, which is restricted to select cell types, is important for fighting infection. Binding of the type 3 interferons to the receptor results in activation of the JAK/STAT signaling pathway.
Interferon-alpha/beta receptor alpha chain is a protein that in humans is encoded by the IFNAR1 gene.
An interferon-stimulated gene (ISG) is a gene that can be expressed in response to stimulation by interferon. Interferons bind to receptors on the surface of a cell, initiating protein signaling pathways within the cell. This interaction leads to the expression of a subset of genes involved in the innate immune system response. ISGs are commonly expressed in response to viral infection, but also during bacterial infection and in the presence of parasites. It's currently estimated that 10% of the human genome is regulated by interferons (IFNs). Interferon stimulated genes can act as an initial response to pathogen invasion, slowing down viral replication and increasing expression of immune signaling complexes. There are three known types of interferon. With approximately 450 genes highly expressed in response to interferon type I. Type I interferon consists of INF-α, INF-β, INF-ω and is expressed in response to viral infection. ISGs induced by type I interferon are associated with viral replication suppression and increase expression of immune signaling proteins. Type II interferon consists only of INF-γ and is associated with controlling intracellular pathogens and tumor suppressor genes. Type III interferon consists of INF-λ and is associated with viral immune response and is key in anti-fungal neutrophil response.
Recombinant feline interferon omega (RFeIFN-ω), sold under the brand name Virbagen Omega among others, is a recombinant version of a cat interferon alpha. It is used to treat a range of viral diseases in cats and dogs, including canine parvovirus, feline leukemia virus (FeLV), and feline immunodeficiency virus (FIV) in many countries. It is approved to be used by injection under the skin. RFeIFN-ω is produced in silkworm larvae using a baculovirus vector.
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