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COVID-19 research v1.26 HLA-C Sarah Leigh changed review comment from: HLA-C was identified through an OMIM search for potential viral susceptibility genes. Initial triage by Illumina (Alison Coffey and team) was given a Tier 3 grouping (experimental evidence and association data consistent with viral susceptibility); to: HLA-C was identified through an OMIM search for potential viral susceptibility genes. Initial triage by Illumina (Alison Coffey and team) was given a Tier 3 grouping (experimental evidence and association data consistent with viral susceptibility). Illumina review: From OMIM: PMID: 11386265 - Gao et al. (2001) concluded that the previously observed association of HLA-Cw*04 with progression to AIDS was due to its linkage disequilibrium with HLA-B*35-Px alleles. PMID:17641165 - Fellay et al. (2007) identified polymorphisms that explain nearly 15% of the variation among individuals in viral load during the asymptomatic set-point period of infection. One of these lies within an endogenous retroviral element and is associated with major histocompatibility allele HLA-B*5701 (142830.0003), whereas a second is located near the HLA-C gene. PMID:19933563 - Thomas et al. (2009) - Genotyped a previously identified varinat 35 kb upstream of the HLA-C gene in 1,698 patients of European ancestry with HIV. Tested cell surface expression of HLA-C in normal donors using an HLA-C-specific antibody. Found that the -35C allele is a proxy for high HLA-C cell surface expression, and that individuals with high surface expression better control viremia and progress more slowly to AIDS. Thomas et al. (2009) concluded that high HLA-C expression results in more effective control of HIV-1, possibly through better antigen presentation to cytotoxic T lymphocytes. PMID 21051598: International HIV Controllers Study performed a GWAS in a multiethnic cohort of HIV-1 controllers and progressors, and analyzed the effects of individual amino acids within the classical human leukocyte antigen (HLA) proteins and demonstrated HLA-C expression affects response to HIV - higher HLA-C expression is associated with better control of HIV-1.
COVID-19 research v1.24 FUT2 Sarah Leigh changed review comment from: FUT2 was identified through an OMIM search for potential viral susceptibility genes. Initial triage by Illumina (Alison Coffey and team) was given a Tier 3 grouping (experimental evidence and association data consistent with viral susceptibility); to: FUT2 was identified through an OMIM search for potential viral susceptibility genes. Initial triage by Illumina (Alison Coffey and team) was given a Tier 3 grouping (experimental evidence and association data consistent with viral susceptibility). Illumina review: PMID: 30845670: Nordgren et al. (2019) (Review) The FUT2 gene encodes FUT2 enzyme, which catalyzes the transfer of fucose to the terminal galactose on glycan chains of cell surface glycoproteins and glycolipids, allowing the synthesis of histo-blood group antigens (HBGAs). The FUT2 gene is expressed predominately in epithelial (mucosal) tissues. Individuals with inactivated FUT2 enzyme, known as “non secretors” do not express blood group antigens in these tissues and are resistant to several norovirus genotypes. FUT2 polymorphisms with known effect on secretor status are present in different populations and are reviewed by Nordgren et al. (2019).
COVID-19 research v1.23 DPP4 Sarah Leigh changed review comment from: DPP4 was identified through an OMIM search for potential viral susceptibility genes. Initial triage by Illumina (Alison Coffey and team) was given a Tier 2 grouping (experimental and/or genetic evidence, suggesting a biological role linking to corona viruses, may not be a GDA); to: DPP4 was identified through an OMIM search for potential viral susceptibility genes. Initial triage by Illumina (Alison Coffey and team) was given a Tier 2 grouping (experimental and/or genetic evidence, suggesting a biological role linking to corona viruses, may not be a GDA). "Illumina review: Cell surface glycoprotein receptor involved in the costimulatory signal essential for T-cell receptor (TCR)-mediated T-cell activation. DPP4 acts as a receptor for MERS-CoV - PMID: 24554656 - Barlan et al. (2014). MERS virus cell entry begins with the receptor-binding domains (RBDs) of the MERS-CoV protein virus spike (S) protein binding to blades 4 and 5 of the 8-blade propeller domain of DPP4. PMID:23486063 - Raj et al. (2013) - identified DPP4 as a functional receptor for hCoV-EMS (MERS CoV). Evidence from mouse models of involvment in susceptibility to MERS-CoV infection. PMID:24599590 - Zhao et al. (2014) - noted that rodents are not susceptible to MERS-CoV. They used an adenovirus vector expressing human DPP4 to generate mice sensitized to infection with MERS-CoV. These mice developed pneumonia characterized by extensive inflammatory cell infiltration with virus clearance after 6 to 8 days in a type I IFN- and T cell-dependent manner. Treatment with poly(I:C) was also efficacious in this model. PMID: 25589660 - Agrawal et al. (2015) developed a transgenic mouse model expressing human DPP4 that was susceptible to MERS-CoV infection, with high titers of virus detectable in brain and lung and later in other organs. PMID: 26124093 - Pascal et al. (2015) - obtained a mouse model susceptible to intranasal infection with MERS-CoV. Human monoclonal antibodies binding to the MERS-CoV S protein neutralized all variants of the virus and prevented entry into target cells. The antibodies could both prevent and treat mice humanized for DPP4. Pascal et al. (2015) concluded that the model will be valuable for assessing treatments for MERS-CoV infection and disease. PMID:31883094 - Leist et al. (2020) - generated a mouse model susceptible to MERS-CoV infection - used C57BL/6J mice and CRISPR/Cas9 to substitute human residues at positions 288 and 330 (A288L and T330R). Strollo et al. (2020) and Bassedine et al. (2020) suggested that DPP4 could affect severity of infection and also be a therapeutic target: PMID:32336077 - Strollo et al. (2020) - propose a role for DDP4 as a functional receptor for SARS-CoV-2 and ask the question if DPP4 is directly involved in SARS-CoV-2 cell adhesion/virulence, and whether DPP4 inhibition might be a therapeutic strategy for preventing infection. PMID:32394639 - Bassedine et al. (2020) - modeling of the structure of SARS-CoV-2 spike glycoprotein predicts that it can interact with human DPP4 in addition to ACE2. Notes that increased DPP4 expression and activity are associated with diabetes, obesity, and metabolic syndrome, all of which have been reported to influence COVID‐19 severity. DPP4 inhibitors (gliptins), which vary in their interactions with the active site of the enzyme, may have immunomodulatory and cardioprotective effects that could be beneficial in COVID‐19 cases. PMID:31964246 - Keline-Weber at al. (2020) - Identified 14 polymorphisms in DPP4 from public databases that alter amino acid residus required for MERS-CoV S binding. Introduction of the respective variants into DPP4 revealed that all except one (Δ346-348) were compatible with robust DPP4 expression. Four polymorphisms (K267E, K267N, A291P and Δ346-348) strongly reduced binding of MERS-CoV S to DPP4 and S protein-driven host cell entry, as determined using soluble S protein and S protein bearing rhabdoviral vectors, respectively. Two polymorphisms (K267E and A291P) were analyzed in the context of authentic MERS-CoV and were found to attenuate viral replication. Collectively, we identified naturally-occurring polymorphisms in DPP4 that negatively impact cellular entry of MERS-CoV and might thus modulate MERS development in infected patients.
COVID-19 research v0.348 DICER1 Rebecca Foulger changed review comment from: Evidence Summary from Illumina curation team: The DICER1 gene, located on chromosome 14, position q32.13, was discovered in 2001 by Bernstein and is a member of the RNase III family, (also known as dicer 1, ribonuclease III; dicer1, Dcr-1 homolog (Drosophila); multinodular goitre 1). DICER1 is involved in the generation of double-stranded microRNAs (miRNAs), short non-coding RNAs, the cleavage of dsRNA into siRNAs, along with the biogenesis of numerous other small RNAs. There is increasing evidence DICER1 is also involved in regulating many other essential cellular processes such as those related to chromatin remodeling, inflammation, apoptosis and cell survival (Kurzynska-Kokorniak et al. 2015; Song and Rossi, 2017). DICER1 encodes a ∼220-KDa protein (RNase III endoribonuclease) which is a crucial component of the RNA Induced Silencing Complex (RISC) loading complex (RLC), comprised of dicer, Argonaute-2 (AGO-2), and trans-activation-responsive RNA binding protein 2 (TARBP2). The encoded protein is required by the RNA interference (RNAi) and small temporal RNA (stRNA) pathways to produce the active small RNA component which has a role in modulating gene expression at the post-transcriptional level. Research has shown that expression levels of cellular transcript and protein dicer are strictly controlled, with aberrant regulation contributing to carcinogenesis, neurodegenerative, rheumatic and immune system disorders. Studies have concluded that the encoded dicer ribonuclease-dependent processing of dsRNA viral replication intermediates into successive siRNAs is a conserved mammalian immune response to infection by positive-strand RNA viruses (Svobodova et al. 2016 summary & fig1; Li et al. 2013; Ding et al. 2018). Moreover, miRNAs play an important role in host-virus interactions in mammals (See Maillard et al. 2019 REVIEW; Foulkes et al. 2014 REVIEW).

IMMUNE SYSTEM
The cre-lox method for dicer1 gene knockout has been employed for studies into the role of dicer1 in immune cell development and function. Studies of dicer1 fl/fl mice have indicated short survival times along with severely impaired GMP differentiation into monocytes, neutrophils, myeloid DCs & mature macrophages. (Devasthanam et al. 2014). Results conclude that dicer1 is important in immune response and also vital for cell survival and apoptosis pathways. Muljo et al. (2005) investigated a conditional allele of dicer-1 (dcr-1) within a mouse model and showed that specific dcr-1 deletion in the T-cell lineage, resulted in impaired development of T-cells & aberrant cell differentiation of T-helper cells & cytokine production. Dcr-1 deletion in the thymus resulted in severe block in development of CD8+ T cells and resulted in defective microRNA processing in CD4+ T-cells. The results demonstrate Dicer regulates diverse aspects of T-cell biology along with cytokine production during T-cell differentiation where dicer-deficient T-cells preferentially express interferon-ƴ.

VIRUSES
Research by Galiana-Arnoux et al. (2006), of DICER in drosophila (drosophila have two dicer genes) have identified that DICER genes (Dcr1, miRNA pathway and Dcr2, RNAi pathway) control production of siRNA and a loss-of-function mutation in Dcr2 resulted in increased susceptibility to three different families of RNA viruses. Qi et al. (2012) research into RNAi gene silencing mechanism show that the B2 protein in Wuhan nodavirus (WhNV) suppresses Dcr2 in drosophila by direct interaction with the PAZ and RNAse III domains therefore blocking processing of dsRNA and siRNA. Evidence of a dicer antiviral system was also reported by Machitani et al. (2016) for mammalian human adenoviruses where DICER1 gene knockdown increased the copy number of adenovirus-encoding small RNAs (VA-RNAs) leading to the promotion of adenovirus replication; conversely, dicer overexpression significantly inhibited viral replication.
Modai et al. (2019) conclude that HIV-1 infection inhibits DICER1 by altering miRNA expression. They conclude that upon HIV-1 infection, human miR-186, 210 and 222 directly regulate DICER1 gene expression causing down-regulation of the gene contributing to impaired cell-mediated immunity (fig6). Other methods of inhibition are from viral proteins, termed viral suppressors of RNA silencing, which interact and inhibit dicer ribonuclease activity in HIV-1 and hepatitis C infections. These viral proteins may mediate proteasomal degradation of endoribonuclease dicer through CRL4DCAF1 ubiquitin ligase complex (Klockow et al. 2013), interact directly via the core protein (Chen et al. 2008) or HIV-1 transactivation of transcription (Bennasser and Jeang, 2006). Through these methods they can block dicer interactions with TRBP2 or ADAR1, boost macrophage infection, and subsequently reduce the function of short hairpin RNAs (shRNAs) which thus inhibit RNA silencing. Ultimately these viruses, though various methods, supress the ability of dicer to process dsRNAs into siRNAs boosting viral infection and pathogenesis.
Downregulation of DICER1 gene expression has additionally been found in cord blood of infants with severe respiratory syncytial virus (RSV), prior to RSV exposure, indicating this reduced expression may predispose newborns to RSV disease. Inchley et al. (2011) theorize that this occurs via disruption of leukocyte gene regulation of miRNA and direct anti-viral RNAi mechanisms. (Inchley et al. 2011 see section on “Dicer Gene Expression”).
Otsuka et al. (2007) have shown using gene-trap methods to obtain viable dicer1 fl/fl mice where dicer1 deficiency caused impairment of miR24 and miR93 production resulting in susceptibility to vesticular stomatitis virus (VSV) and herpes simplex-1 virus, but not other viruses tested.

SARS CoV & SARS CoV-2
Recently, Pasquier and Robichon, 2020 (preprint) have investigated the Dicer host immunity system regarding SARs-CoV-2 within a computational approach, concluding SARS-CoV2 may manipulate this system of immunity against its host, requiring further research. Mu et al., 2020 suggest SARs-CoV2 suppresses RNAi thus preventing recognition by the encoded ribonuclease dicer protein
Viral suppressors of RNA silencing (VSRs) suppress RNAi at pre or post-dicer level to overcome host defense and establish infection. Cui et al. (2015) from Wuhan University laboratory of virology, identified a novel VSR from coronaviruses (CoVs) including Severe acute respiratory syndrome coronavirus (SARS-CoV) and showed that the coronavirus nucelocaspid protein (N-protein), conserved and expressed in all coronaviruses, suppressed RNAi triggered by either short hairpin RNAs or small interfering RNAs in mammalian cells. They went on to show using mouse hepatitis virus A-59 (MHV-A59) which is closely linked to SARS-CoV in the family coronaviridae, that the viral replication was increased when the N proteins (novel VSR) were expressed but that knockdown of DICER1 gene or Ago2 transcripts facilitated the viral replication specifically in mammalian cells. They demonstrate that the N-protein of CoVs could efficiently inhibit dicer-mediated dsRNA cleavage and post-Dicer activities by sequestering dsRNAs and siRNAs. Kannan et al. (2020) performed clustal W analysis of N-Protein for SARS-CoV and COVID-19 demonstrating 90% sequence identity from an NCBI amino acid blast of both nucleocapsid (N) protein sequences (figure2). They suggest that the N-protein of COVID-19 may also function as a VSR for RNAi to overcome host defense. Ding et al. (2017) show that both MHV and SARS-CoV N proteins can also disrupt protein activator of protein kinase R (PACT), a cellular dsRNA-binding protein which binds to RIG-I and MDA5 to activate interferon (IFN) production to prevent antiviral host response.

Literature Review
PMID: 17181864: Bennasser and Jeang, 2006
• HIV-1 Tat Interaction With Dicer: Requirement for RNA
• Tat-Dicer interaction depends on RNA, requires the helicase domain of Dicer, and is independent of Tat's transactivation domain.

PMID: 18325616: Chen et al., 2008
• HCV Core Protein Interacts With Dicer to Antagonize RNA Silencing

PMID: 26085159: Cui et al., 2015
• The Nucleocapsid Protein of Coronaviruses Acts as a Viral Suppressor of RNA Silencing in Mammalian Cells

PMID: 24303839: Devasthanam et al, 2014
• This study investigates the role of the dicer protein in immune cell development and function using dicer1 cre-lox knockout models to conditionally ablate dicer1 in different immune cell subsets.

PMID: 28591694: Ding et al., 2017
• The nucleocapsid proteins of mouse hepatitis virus and severe acute respiratory syndrome coronavirus share the same IFN-β antagonizing mechanism: attenuation of PACT-mediated RIG-I/MDA5 activation

PMID: 30015086: Ding et al., 2018
• Antiviral RNA Interference in Mammals: Indicates infection of plants and insects with RNA and DNA viruses triggers Dicer-dependent production of virus-derived small interfering RNAs (vsiRNAs), which subsequently guide specific virus clearance by RNA interference (RNAi).

PMID: 25176334: Foulkes et al., 2012-REVIEW
• Review of DICER1: DICER1 Mutations, microRNAs and Mechanisms

PMID: 16554838: Galiana-Arnoux et al., 2006
• Essential function in vivo for Dicer-2 in host defense against RNA viruses in drosophila.
• https://pubmed.ncbi.nlm.nih.gov/16554838/ or https://www.nature.com/articles/ni1335

PMID: 21385408: Inchley et al., 2011
• Investigates ribonuclease Dicer and analyzed the gene expression of Dicer in newborns of which 37 infants had sufficient cord blood RNA with confirmed RSV disease <1yr. Demonstrates significant reduced Dicer expression in cord blood prior to severe disease in infants <1yr later. Conclude downregulation may predispose infants to RSV disease.

PMID: 32141569: Kannan et al., 2020
• COVID-19 (Novel Coronavirus 2019) - Recent Trends
• Perform W cluster analysis of COVID-19 and SARS-CoV nucleocapsid (N) protein sequences of the viruses showing 90% amino acid sequence similarity. Suggest the N-protein may be a VSR in RNAi by targeting DICER.

PMID: 23849790: Klockow et al., 2013
• The HIV-1 Protein Vpr Targets the Endoribonuclease Dicer for Proteasomal Degradation to Boost Macrophage Infection

PMID: 25883138: Kurzynska-Kokorniak et al., 2015
• Investigating the complexity of the mechanisms regulating Dicer gene expression and enzyme activities

PMID: 24115437: Li et al, 2013
• Investigates RNA interference pathways in antiviral immunity in mammals overviewing dicer processing of dsRNA viral replication intermediates into siRNAs.

PMID: 27273616: Machitani et al., 2016
• Dicer functions as an antiviral system against human adenoviruses via cleavage of adenovirus-encoded noncoding RNA

PMID: 30872283: Maillard et al., 2019- REVIEW
• Reviewing DICER1 within the anti-viral RNAi pathway in mammals

PMID: 30682089: Modai et al, 2019
• HIV-1 infection increases miRNAs which inhibit Dicer

PMID: 32291557: Mu et al, 2020
• SARS-CoV-2-encoded nucleocapsid protein acts as a viral suppressor of RNA interference in cells

PMID: 16009718: Muljo et al., 2005
• Indicates absence of dicer results in abberant T-cell differentiation.

PMID: 17613256: Otsuka, et al 2007
• Hypersusceptibility to Vesicular Stomatitis Virus Infection in Dicer1-Deficient Mice Is Due to Impaired miR24 and miR93 Expression

No PMID: Preprint : Pasquier and Rubichon, 2020
• SARS-CoV-2 might manipulate against its host the immunity RNAi/Dicer/Ago system

PMID: 22438534: Qi et al., 2012
• Targeting of Dicer-2 and RNA by a Viral RNA Silencing Suppressor in Drosophila Cells

PMID: 28473628: Song and Rossi, 2017
• Molecular Mechanisms of Dicer: Endonuclease and Enzymatic Activity; to: Evidence Summary from Illumina curation team (Alison Coffey and Julie Taylor): The DICER1 gene, located on chromosome 14, position q32.13, was discovered in 2001 by Bernstein and is a member of the RNase III family, (also known as dicer 1, ribonuclease III; dicer1, Dcr-1 homolog (Drosophila); multinodular goitre 1). DICER1 is involved in the generation of double-stranded microRNAs (miRNAs), short non-coding RNAs, the cleavage of dsRNA into siRNAs, along with the biogenesis of numerous other small RNAs. There is increasing evidence DICER1 is also involved in regulating many other essential cellular processes such as those related to chromatin remodeling, inflammation, apoptosis and cell survival (Kurzynska-Kokorniak et al. 2015; Song and Rossi, 2017). DICER1 encodes a ∼220-KDa protein (RNase III endoribonuclease) which is a crucial component of the RNA Induced Silencing Complex (RISC) loading complex (RLC), comprised of dicer, Argonaute-2 (AGO-2), and trans-activation-responsive RNA binding protein 2 (TARBP2). The encoded protein is required by the RNA interference (RNAi) and small temporal RNA (stRNA) pathways to produce the active small RNA component which has a role in modulating gene expression at the post-transcriptional level. Research has shown that expression levels of cellular transcript and protein dicer are strictly controlled, with aberrant regulation contributing to carcinogenesis, neurodegenerative, rheumatic and immune system disorders. Studies have concluded that the encoded dicer ribonuclease-dependent processing of dsRNA viral replication intermediates into successive siRNAs is a conserved mammalian immune response to infection by positive-strand RNA viruses (Svobodova et al. 2016 summary & fig1; Li et al. 2013; Ding et al. 2018). Moreover, miRNAs play an important role in host-virus interactions in mammals (See Maillard et al. 2019 REVIEW; Foulkes et al. 2014 REVIEW).

IMMUNE SYSTEM
The cre-lox method for dicer1 gene knockout has been employed for studies into the role of dicer1 in immune cell development and function. Studies of dicer1 fl/fl mice have indicated short survival times along with severely impaired GMP differentiation into monocytes, neutrophils, myeloid DCs & mature macrophages. (Devasthanam et al. 2014). Results conclude that dicer1 is important in immune response and also vital for cell survival and apoptosis pathways. Muljo et al. (2005) investigated a conditional allele of dicer-1 (dcr-1) within a mouse model and showed that specific dcr-1 deletion in the T-cell lineage, resulted in impaired development of T-cells & aberrant cell differentiation of T-helper cells & cytokine production. Dcr-1 deletion in the thymus resulted in severe block in development of CD8+ T cells and resulted in defective microRNA processing in CD4+ T-cells. The results demonstrate Dicer regulates diverse aspects of T-cell biology along with cytokine production during T-cell differentiation where dicer-deficient T-cells preferentially express interferon-ƴ.

VIRUSES
Research by Galiana-Arnoux et al. (2006), of DICER in drosophila (drosophila have two dicer genes) have identified that DICER genes (Dcr1, miRNA pathway and Dcr2, RNAi pathway) control production of siRNA and a loss-of-function mutation in Dcr2 resulted in increased susceptibility to three different families of RNA viruses. Qi et al. (2012) research into RNAi gene silencing mechanism show that the B2 protein in Wuhan nodavirus (WhNV) suppresses Dcr2 in drosophila by direct interaction with the PAZ and RNAse III domains therefore blocking processing of dsRNA and siRNA. Evidence of a dicer antiviral system was also reported by Machitani et al. (2016) for mammalian human adenoviruses where DICER1 gene knockdown increased the copy number of adenovirus-encoding small RNAs (VA-RNAs) leading to the promotion of adenovirus replication; conversely, dicer overexpression significantly inhibited viral replication.
Modai et al. (2019) conclude that HIV-1 infection inhibits DICER1 by altering miRNA expression. They conclude that upon HIV-1 infection, human miR-186, 210 and 222 directly regulate DICER1 gene expression causing down-regulation of the gene contributing to impaired cell-mediated immunity (fig6). Other methods of inhibition are from viral proteins, termed viral suppressors of RNA silencing, which interact and inhibit dicer ribonuclease activity in HIV-1 and hepatitis C infections. These viral proteins may mediate proteasomal degradation of endoribonuclease dicer through CRL4DCAF1 ubiquitin ligase complex (Klockow et al. 2013), interact directly via the core protein (Chen et al. 2008) or HIV-1 transactivation of transcription (Bennasser and Jeang, 2006). Through these methods they can block dicer interactions with TRBP2 or ADAR1, boost macrophage infection, and subsequently reduce the function of short hairpin RNAs (shRNAs) which thus inhibit RNA silencing. Ultimately these viruses, though various methods, supress the ability of dicer to process dsRNAs into siRNAs boosting viral infection and pathogenesis.
Downregulation of DICER1 gene expression has additionally been found in cord blood of infants with severe respiratory syncytial virus (RSV), prior to RSV exposure, indicating this reduced expression may predispose newborns to RSV disease. Inchley et al. (2011) theorize that this occurs via disruption of leukocyte gene regulation of miRNA and direct anti-viral RNAi mechanisms. (Inchley et al. 2011 see section on “Dicer Gene Expression”).
Otsuka et al. (2007) have shown using gene-trap methods to obtain viable dicer1 fl/fl mice where dicer1 deficiency caused impairment of miR24 and miR93 production resulting in susceptibility to vesticular stomatitis virus (VSV) and herpes simplex-1 virus, but not other viruses tested.

SARS CoV & SARS CoV-2
Recently, Pasquier and Robichon, 2020 (preprint) have investigated the Dicer host immunity system regarding SARs-CoV-2 within a computational approach, concluding SARS-CoV2 may manipulate this system of immunity against its host, requiring further research. Mu et al., 2020 suggest SARs-CoV2 suppresses RNAi thus preventing recognition by the encoded ribonuclease dicer protein
Viral suppressors of RNA silencing (VSRs) suppress RNAi at pre or post-dicer level to overcome host defense and establish infection. Cui et al. (2015) from Wuhan University laboratory of virology, identified a novel VSR from coronaviruses (CoVs) including Severe acute respiratory syndrome coronavirus (SARS-CoV) and showed that the coronavirus nucelocaspid protein (N-protein), conserved and expressed in all coronaviruses, suppressed RNAi triggered by either short hairpin RNAs or small interfering RNAs in mammalian cells. They went on to show using mouse hepatitis virus A-59 (MHV-A59) which is closely linked to SARS-CoV in the family coronaviridae, that the viral replication was increased when the N proteins (novel VSR) were expressed but that knockdown of DICER1 gene or Ago2 transcripts facilitated the viral replication specifically in mammalian cells. They demonstrate that the N-protein of CoVs could efficiently inhibit dicer-mediated dsRNA cleavage and post-Dicer activities by sequestering dsRNAs and siRNAs. Kannan et al. (2020) performed clustal W analysis of N-Protein for SARS-CoV and COVID-19 demonstrating 90% sequence identity from an NCBI amino acid blast of both nucleocapsid (N) protein sequences (figure2). They suggest that the N-protein of COVID-19 may also function as a VSR for RNAi to overcome host defense. Ding et al. (2017) show that both MHV and SARS-CoV N proteins can also disrupt protein activator of protein kinase R (PACT), a cellular dsRNA-binding protein which binds to RIG-I and MDA5 to activate interferon (IFN) production to prevent antiviral host response.

Literature Review
PMID: 17181864: Bennasser and Jeang, 2006
• HIV-1 Tat Interaction With Dicer: Requirement for RNA
• Tat-Dicer interaction depends on RNA, requires the helicase domain of Dicer, and is independent of Tat's transactivation domain.

PMID: 18325616: Chen et al., 2008
• HCV Core Protein Interacts With Dicer to Antagonize RNA Silencing

PMID: 26085159: Cui et al., 2015
• The Nucleocapsid Protein of Coronaviruses Acts as a Viral Suppressor of RNA Silencing in Mammalian Cells

PMID: 24303839: Devasthanam et al, 2014
• This study investigates the role of the dicer protein in immune cell development and function using dicer1 cre-lox knockout models to conditionally ablate dicer1 in different immune cell subsets.

PMID: 28591694: Ding et al., 2017
• The nucleocapsid proteins of mouse hepatitis virus and severe acute respiratory syndrome coronavirus share the same IFN-β antagonizing mechanism: attenuation of PACT-mediated RIG-I/MDA5 activation

PMID: 30015086: Ding et al., 2018
• Antiviral RNA Interference in Mammals: Indicates infection of plants and insects with RNA and DNA viruses triggers Dicer-dependent production of virus-derived small interfering RNAs (vsiRNAs), which subsequently guide specific virus clearance by RNA interference (RNAi).

PMID: 25176334: Foulkes et al., 2012-REVIEW
• Review of DICER1: DICER1 Mutations, microRNAs and Mechanisms

PMID: 16554838: Galiana-Arnoux et al., 2006
• Essential function in vivo for Dicer-2 in host defense against RNA viruses in drosophila.
• https://pubmed.ncbi.nlm.nih.gov/16554838/ or https://www.nature.com/articles/ni1335

PMID: 21385408: Inchley et al., 2011
• Investigates ribonuclease Dicer and analyzed the gene expression of Dicer in newborns of which 37 infants had sufficient cord blood RNA with confirmed RSV disease <1yr. Demonstrates significant reduced Dicer expression in cord blood prior to severe disease in infants <1yr later. Conclude downregulation may predispose infants to RSV disease.

PMID: 32141569: Kannan et al., 2020
• COVID-19 (Novel Coronavirus 2019) - Recent Trends
• Perform W cluster analysis of COVID-19 and SARS-CoV nucleocapsid (N) protein sequences of the viruses showing 90% amino acid sequence similarity. Suggest the N-protein may be a VSR in RNAi by targeting DICER.

PMID: 23849790: Klockow et al., 2013
• The HIV-1 Protein Vpr Targets the Endoribonuclease Dicer for Proteasomal Degradation to Boost Macrophage Infection

PMID: 25883138: Kurzynska-Kokorniak et al., 2015
• Investigating the complexity of the mechanisms regulating Dicer gene expression and enzyme activities

PMID: 24115437: Li et al, 2013
• Investigates RNA interference pathways in antiviral immunity in mammals overviewing dicer processing of dsRNA viral replication intermediates into siRNAs.

PMID: 27273616: Machitani et al., 2016
• Dicer functions as an antiviral system against human adenoviruses via cleavage of adenovirus-encoded noncoding RNA

PMID: 30872283: Maillard et al., 2019- REVIEW
• Reviewing DICER1 within the anti-viral RNAi pathway in mammals

PMID: 30682089: Modai et al, 2019
• HIV-1 infection increases miRNAs which inhibit Dicer

PMID: 32291557: Mu et al, 2020
• SARS-CoV-2-encoded nucleocapsid protein acts as a viral suppressor of RNA interference in cells

PMID: 16009718: Muljo et al., 2005
• Indicates absence of dicer results in abberant T-cell differentiation.

PMID: 17613256: Otsuka, et al 2007
• Hypersusceptibility to Vesicular Stomatitis Virus Infection in Dicer1-Deficient Mice Is Due to Impaired miR24 and miR93 Expression

No PMID: Preprint : Pasquier and Rubichon, 2020
• SARS-CoV-2 might manipulate against its host the immunity RNAi/Dicer/Ago system

PMID: 22438534: Qi et al., 2012
• Targeting of Dicer-2 and RNA by a Viral RNA Silencing Suppressor in Drosophila Cells

PMID: 28473628: Song and Rossi, 2017
• Molecular Mechanisms of Dicer: Endonuclease and Enzymatic Activity
COVID-19 research v0.348 DICER1 Rebecca Foulger commented on gene: DICER1: Evidence Summary from Illumina curation team: The DICER1 gene, located on chromosome 14, position q32.13, was discovered in 2001 by Bernstein and is a member of the RNase III family, (also known as dicer 1, ribonuclease III; dicer1, Dcr-1 homolog (Drosophila); multinodular goitre 1). DICER1 is involved in the generation of double-stranded microRNAs (miRNAs), short non-coding RNAs, the cleavage of dsRNA into siRNAs, along with the biogenesis of numerous other small RNAs. There is increasing evidence DICER1 is also involved in regulating many other essential cellular processes such as those related to chromatin remodeling, inflammation, apoptosis and cell survival (Kurzynska-Kokorniak et al. 2015; Song and Rossi, 2017). DICER1 encodes a ∼220-KDa protein (RNase III endoribonuclease) which is a crucial component of the RNA Induced Silencing Complex (RISC) loading complex (RLC), comprised of dicer, Argonaute-2 (AGO-2), and trans-activation-responsive RNA binding protein 2 (TARBP2). The encoded protein is required by the RNA interference (RNAi) and small temporal RNA (stRNA) pathways to produce the active small RNA component which has a role in modulating gene expression at the post-transcriptional level. Research has shown that expression levels of cellular transcript and protein dicer are strictly controlled, with aberrant regulation contributing to carcinogenesis, neurodegenerative, rheumatic and immune system disorders. Studies have concluded that the encoded dicer ribonuclease-dependent processing of dsRNA viral replication intermediates into successive siRNAs is a conserved mammalian immune response to infection by positive-strand RNA viruses (Svobodova et al. 2016 summary & fig1; Li et al. 2013; Ding et al. 2018). Moreover, miRNAs play an important role in host-virus interactions in mammals (See Maillard et al. 2019 REVIEW; Foulkes et al. 2014 REVIEW).

IMMUNE SYSTEM
The cre-lox method for dicer1 gene knockout has been employed for studies into the role of dicer1 in immune cell development and function. Studies of dicer1 fl/fl mice have indicated short survival times along with severely impaired GMP differentiation into monocytes, neutrophils, myeloid DCs & mature macrophages. (Devasthanam et al. 2014). Results conclude that dicer1 is important in immune response and also vital for cell survival and apoptosis pathways. Muljo et al. (2005) investigated a conditional allele of dicer-1 (dcr-1) within a mouse model and showed that specific dcr-1 deletion in the T-cell lineage, resulted in impaired development of T-cells & aberrant cell differentiation of T-helper cells & cytokine production. Dcr-1 deletion in the thymus resulted in severe block in development of CD8+ T cells and resulted in defective microRNA processing in CD4+ T-cells. The results demonstrate Dicer regulates diverse aspects of T-cell biology along with cytokine production during T-cell differentiation where dicer-deficient T-cells preferentially express interferon-ƴ.

VIRUSES
Research by Galiana-Arnoux et al. (2006), of DICER in drosophila (drosophila have two dicer genes) have identified that DICER genes (Dcr1, miRNA pathway and Dcr2, RNAi pathway) control production of siRNA and a loss-of-function mutation in Dcr2 resulted in increased susceptibility to three different families of RNA viruses. Qi et al. (2012) research into RNAi gene silencing mechanism show that the B2 protein in Wuhan nodavirus (WhNV) suppresses Dcr2 in drosophila by direct interaction with the PAZ and RNAse III domains therefore blocking processing of dsRNA and siRNA. Evidence of a dicer antiviral system was also reported by Machitani et al. (2016) for mammalian human adenoviruses where DICER1 gene knockdown increased the copy number of adenovirus-encoding small RNAs (VA-RNAs) leading to the promotion of adenovirus replication; conversely, dicer overexpression significantly inhibited viral replication.
Modai et al. (2019) conclude that HIV-1 infection inhibits DICER1 by altering miRNA expression. They conclude that upon HIV-1 infection, human miR-186, 210 and 222 directly regulate DICER1 gene expression causing down-regulation of the gene contributing to impaired cell-mediated immunity (fig6). Other methods of inhibition are from viral proteins, termed viral suppressors of RNA silencing, which interact and inhibit dicer ribonuclease activity in HIV-1 and hepatitis C infections. These viral proteins may mediate proteasomal degradation of endoribonuclease dicer through CRL4DCAF1 ubiquitin ligase complex (Klockow et al. 2013), interact directly via the core protein (Chen et al. 2008) or HIV-1 transactivation of transcription (Bennasser and Jeang, 2006). Through these methods they can block dicer interactions with TRBP2 or ADAR1, boost macrophage infection, and subsequently reduce the function of short hairpin RNAs (shRNAs) which thus inhibit RNA silencing. Ultimately these viruses, though various methods, supress the ability of dicer to process dsRNAs into siRNAs boosting viral infection and pathogenesis.
Downregulation of DICER1 gene expression has additionally been found in cord blood of infants with severe respiratory syncytial virus (RSV), prior to RSV exposure, indicating this reduced expression may predispose newborns to RSV disease. Inchley et al. (2011) theorize that this occurs via disruption of leukocyte gene regulation of miRNA and direct anti-viral RNAi mechanisms. (Inchley et al. 2011 see section on “Dicer Gene Expression”).
Otsuka et al. (2007) have shown using gene-trap methods to obtain viable dicer1 fl/fl mice where dicer1 deficiency caused impairment of miR24 and miR93 production resulting in susceptibility to vesticular stomatitis virus (VSV) and herpes simplex-1 virus, but not other viruses tested.

SARS CoV & SARS CoV-2
Recently, Pasquier and Robichon, 2020 (preprint) have investigated the Dicer host immunity system regarding SARs-CoV-2 within a computational approach, concluding SARS-CoV2 may manipulate this system of immunity against its host, requiring further research. Mu et al., 2020 suggest SARs-CoV2 suppresses RNAi thus preventing recognition by the encoded ribonuclease dicer protein
Viral suppressors of RNA silencing (VSRs) suppress RNAi at pre or post-dicer level to overcome host defense and establish infection. Cui et al. (2015) from Wuhan University laboratory of virology, identified a novel VSR from coronaviruses (CoVs) including Severe acute respiratory syndrome coronavirus (SARS-CoV) and showed that the coronavirus nucelocaspid protein (N-protein), conserved and expressed in all coronaviruses, suppressed RNAi triggered by either short hairpin RNAs or small interfering RNAs in mammalian cells. They went on to show using mouse hepatitis virus A-59 (MHV-A59) which is closely linked to SARS-CoV in the family coronaviridae, that the viral replication was increased when the N proteins (novel VSR) were expressed but that knockdown of DICER1 gene or Ago2 transcripts facilitated the viral replication specifically in mammalian cells. They demonstrate that the N-protein of CoVs could efficiently inhibit dicer-mediated dsRNA cleavage and post-Dicer activities by sequestering dsRNAs and siRNAs. Kannan et al. (2020) performed clustal W analysis of N-Protein for SARS-CoV and COVID-19 demonstrating 90% sequence identity from an NCBI amino acid blast of both nucleocapsid (N) protein sequences (figure2). They suggest that the N-protein of COVID-19 may also function as a VSR for RNAi to overcome host defense. Ding et al. (2017) show that both MHV and SARS-CoV N proteins can also disrupt protein activator of protein kinase R (PACT), a cellular dsRNA-binding protein which binds to RIG-I and MDA5 to activate interferon (IFN) production to prevent antiviral host response.

Literature Review
PMID: 17181864: Bennasser and Jeang, 2006
• HIV-1 Tat Interaction With Dicer: Requirement for RNA
• Tat-Dicer interaction depends on RNA, requires the helicase domain of Dicer, and is independent of Tat's transactivation domain.

PMID: 18325616: Chen et al., 2008
• HCV Core Protein Interacts With Dicer to Antagonize RNA Silencing

PMID: 26085159: Cui et al., 2015
• The Nucleocapsid Protein of Coronaviruses Acts as a Viral Suppressor of RNA Silencing in Mammalian Cells

PMID: 24303839: Devasthanam et al, 2014
• This study investigates the role of the dicer protein in immune cell development and function using dicer1 cre-lox knockout models to conditionally ablate dicer1 in different immune cell subsets.

PMID: 28591694: Ding et al., 2017
• The nucleocapsid proteins of mouse hepatitis virus and severe acute respiratory syndrome coronavirus share the same IFN-β antagonizing mechanism: attenuation of PACT-mediated RIG-I/MDA5 activation

PMID: 30015086: Ding et al., 2018
• Antiviral RNA Interference in Mammals: Indicates infection of plants and insects with RNA and DNA viruses triggers Dicer-dependent production of virus-derived small interfering RNAs (vsiRNAs), which subsequently guide specific virus clearance by RNA interference (RNAi).

PMID: 25176334: Foulkes et al., 2012-REVIEW
• Review of DICER1: DICER1 Mutations, microRNAs and Mechanisms

PMID: 16554838: Galiana-Arnoux et al., 2006
• Essential function in vivo for Dicer-2 in host defense against RNA viruses in drosophila.
• https://pubmed.ncbi.nlm.nih.gov/16554838/ or https://www.nature.com/articles/ni1335

PMID: 21385408: Inchley et al., 2011
• Investigates ribonuclease Dicer and analyzed the gene expression of Dicer in newborns of which 37 infants had sufficient cord blood RNA with confirmed RSV disease <1yr. Demonstrates significant reduced Dicer expression in cord blood prior to severe disease in infants <1yr later. Conclude downregulation may predispose infants to RSV disease.

PMID: 32141569: Kannan et al., 2020
• COVID-19 (Novel Coronavirus 2019) - Recent Trends
• Perform W cluster analysis of COVID-19 and SARS-CoV nucleocapsid (N) protein sequences of the viruses showing 90% amino acid sequence similarity. Suggest the N-protein may be a VSR in RNAi by targeting DICER.

PMID: 23849790: Klockow et al., 2013
• The HIV-1 Protein Vpr Targets the Endoribonuclease Dicer for Proteasomal Degradation to Boost Macrophage Infection

PMID: 25883138: Kurzynska-Kokorniak et al., 2015
• Investigating the complexity of the mechanisms regulating Dicer gene expression and enzyme activities

PMID: 24115437: Li et al, 2013
• Investigates RNA interference pathways in antiviral immunity in mammals overviewing dicer processing of dsRNA viral replication intermediates into siRNAs.

PMID: 27273616: Machitani et al., 2016
• Dicer functions as an antiviral system against human adenoviruses via cleavage of adenovirus-encoded noncoding RNA

PMID: 30872283: Maillard et al., 2019- REVIEW
• Reviewing DICER1 within the anti-viral RNAi pathway in mammals

PMID: 30682089: Modai et al, 2019
• HIV-1 infection increases miRNAs which inhibit Dicer

PMID: 32291557: Mu et al, 2020
• SARS-CoV-2-encoded nucleocapsid protein acts as a viral suppressor of RNA interference in cells

PMID: 16009718: Muljo et al., 2005
• Indicates absence of dicer results in abberant T-cell differentiation.

PMID: 17613256: Otsuka, et al 2007
• Hypersusceptibility to Vesicular Stomatitis Virus Infection in Dicer1-Deficient Mice Is Due to Impaired miR24 and miR93 Expression

No PMID: Preprint : Pasquier and Rubichon, 2020
• SARS-CoV-2 might manipulate against its host the immunity RNAi/Dicer/Ago system

PMID: 22438534: Qi et al., 2012
• Targeting of Dicer-2 and RNA by a Viral RNA Silencing Suppressor in Drosophila Cells

PMID: 28473628: Song and Rossi, 2017
• Molecular Mechanisms of Dicer: Endonuclease and Enzymatic Activity
COVID-19 research v0.232 ACE2 Eleanor Williams changed review comment from: PMID: 32133153 Cao et al 2020 - Analyzed coding-region variants in ACE2 and the eQTL variants, which may affect the expression of ACE2 using the GTEx database to compare the genomic characteristics of ACE2 among different populations. Their findings indicated that no direct evidence was identified genetically supporting the existence of coronavirus S-protein binding-resistant ACE2 mutants in different populations.; to: PMID: 32133153 Cao et al 2020 - Analyzed coding-region variants in ACE2 and the eQTL variants, which may affect the expression of ACE2 using the GTEx database to compare the genomic characteristics of ACE2 among different populations. Their findings indicated that no direct evidence was identified genetically supporting the existence of coronavirus S-protein binding-resistant ACE2 mutants in different populations. East Asian populations have much higher AFs in the eQTL variants associated with higher ACE2 expression in tissues.
COVID-19 research v0.231 ACE2 Eleanor Williams commented on gene: ACE2: PMID: 32133153 Cao et al 2020 - Analyzed coding-region variants in ACE2 and the eQTL variants, which may affect the expression of ACE2 using the GTEx database to compare the genomic characteristics of ACE2 among different populations. Their findings indicated that no direct evidence was identified genetically supporting the existence of coronavirus S-protein binding-resistant ACE2 mutants in different populations.
COVID-19 research v0.138 TRIB3 Eleanor Williams gene: TRIB3 was added
gene: TRIB3 was added to Viral susceptibility. Sources: Literature
Mode of inheritance for gene: TRIB3 was set to Unknown
Publications for gene: TRIB3 were set to 27252525; https://www.biorxiv.org/content/10.1101/2020.04.07.030767v1
Added comment: Preprint - https://www.biorxiv.org/content/10.1101/2020.04.07.030767v1 - de Moraes et al
Analyzed Genotype-Tissue Expression (GTEx) data to test whether lung aging is associated with transcriptional changes in human protein-coding genes that potentially interact with these viruses. Identified TRIB3 expression was decreased in older males. Found TRIB3
expressed mainly in alveolar epithelial cells that express SARS-CoV-2 receptor ACE2.

PMID: 27252525 - Tran et al 2016- Silencing of TRIB3 resulted in increased RNA and protein levels of HCV, whereas overexpression of TRIB3 decreased Hepatitis C viral replication
Sources: Literature
COVID-19 research v0.81 HLA-DRB1 Abdelazeem Elhabyan gene: HLA-DRB1 was added
gene: HLA-DRB1 was added to Viral susceptibility. Sources: Literature
Mode of inheritance for gene: HLA-DRB1 was set to Unknown
Publications for gene: HLA-DRB1 were set to PMID: 19445991,26456283,19597844,10823757,
Penetrance for gene: HLA-DRB1 were set to unknown
Mode of pathogenicity for gene: HLA-DRB1 was set to Other
Review for gene: HLA-DRB1 was set to GREEN
Added comment: Association of human leukocyte antigen class II alleles with severe acute respiratory syndrome in the Vietnamese population PMID: 19445991,

HLA-DRB1*12 was more frequently shown in SARS patients than in controls (corrected p = 0.042). HLA-DRB1*1202, the predominant allele in the Vietnamese population showed the strongest association with SARS in a dominant model (corrected p = 0.0065 and 0.0052, depending on the controls to be compared). Our results and accumulated data on HLA in the Asian populations would help in the understanding of associations with emerging infectious diseases.

Amino Acid Variation in HLA Class II Proteins Is a Major Determinant of Humoral Response to Common Viruses PMID: 26456283
The magnitude of the human antibody response to viral antigens is highly variable. To explore the human genetic contribution to this variability, we performed genome-wide association studies of the immunoglobulin G response to 14 pathogenic viruses in 2,363 immunocompetent adults. Significant associations were observed in the major histocompatibility complex region on chromosome 6 for influenza A virus, Epstein-Barr virus, JC polyomavirus, and Merkel cell polyomavirus. Using local imputation and fine mapping, we identified specific amino acid residues in human leucocyte antigen (HLA) class II proteins as the most probable causal variants underlying these association signals. Common HLA-DRβ1 haplotypes showed virus-specific patterns of humoral-response regulation

Clear and Independent Associations of Several HLA-DRB1 Alleles With Differential Antibody Responses to Hepatitis B Vaccination in Youth
PMID: 19597844
To confirm and refine associations of human leukocyte antigen (HLA) genotypes with variable antibody (Ab) responses to hepatitis B vaccination, we have analyzed 255 HIV-1 seropositive (HIV(+)) youth and 80 HIV-1 seronegatives (HIV(-)) enrolled into prospective studies. In univariate analyses that focused on HLA-DRB1, -DQA1, and -DQB1 alleles and haplotypes, the DRB1*03 allele group and DRB1*0701 were negatively associated with the responder phenotype (serum Ab concentration > or = 10 mIU/mL) (P = 0.026 and 0.043, respectively). Collectively, DRB1*03 and DRB1*0701 were found in 42 (53.8%) out of 78 non-responders (serum Ab <10 mIU/mL), 65 (40.6%) out of 160 medium responders (serum Ab 10-1,000 mIU/mL), and 27 (27.8%) out of 97 high responders (serum Ab >1,000 mIU/mL) (P < 0.001 for trend). Meanwhile, DRB1*08 was positively associated with the responder phenotype (P = 0.010), mostly due to DRB1*0804 (P = 0.008).

Influence of HLA Supertypes on Susceptibility and Resistance to Human Immunodeficiency Virus Type 1 Infection
PMID: 10823757
To determine whether HLA polymorphism influences HIV-1 susceptibility, a longitudinal cohort of highly HIV-1-exposed female sex workers based in Nairobi, Kenya, was prospectively analyzed. Decreased HIV-1 infection risk was strongly associated with possession of a cluster of closely related HLA alleles (A2/6802 supertype; incidence rate ratio [IRR], 0.45; 95% confidence interval [CI], 0.27-0.72; P=.0003). The alleles in this supertype are known in some cases to present the same peptide epitopes for T cell recognition. In addition, resistance to HIV-1 infection was independently associated with HLA DRB1*01 (IRR, 0.22; 95% CI, 0.06-0.60; P=.0003), which suggests that anti-HIV-1 class II restricted CD4 effector mechanisms may play an important role in protecting against viral challenge
Sources: Literature
COVID-19 research v0.36 LYZ Ellen McDonagh gene: LYZ was added
gene: LYZ was added to Viral susceptibility. Sources: Expert Review Red,NHS GMS,London North GLH
Mode of inheritance for gene: LYZ was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Phenotypes for gene: LYZ were set to Amyloidosis, renal, 105200