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1.
Adv Drug Deliv Rev ; 179: 114020, 2021 12.
Article in English | MEDLINE | ID: covidwho-1486938

ABSTRACT

Adjuvant is an essential component in subunit vaccines. Many agonists of pathogen recognition receptors have been developed as potent adjuvants to optimize the immunogenicity and efficacy of vaccines. Recently discovered cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway has attracted much attention as it is a key mediator for modulating immune responses. Vaccines adjuvanted with STING agonists are found to mediate a robust immune defense against infections and cancer. In this review, we first discuss the mechanisms of STING agonists in the context of vaccination. Next, we present recent progress in novel STING agonist discovery and the delivery strategies. We next highlight recent work in optimizing the efficacy while minimizing toxicity of STING agonist-assisted subunit vaccines for protection against infectious diseases or treatment of cancer. Finally, we share our perspectives of current issues and future directions in further developing STING agonists for adjuvanting subunit vaccines.


Subject(s)
Adjuvants, Immunologic/administration & dosage , Membrane Proteins/agonists , Membrane Proteins/immunology , Vaccines, Subunit/immunology , CD4-Positive T-Lymphocytes/drug effects , CD8-Positive T-Lymphocytes/drug effects , Dendritic Cells/drug effects , Humans , Immunity, Humoral/drug effects , Nucleotidyltransferases/metabolism
2.
Sci Immunol ; 6(59)2021 05 18.
Article in English | MEDLINE | ID: covidwho-1234281

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a global pandemic, resulting millions of infections and deaths with few effective interventions available. Here, we demonstrate that SARS-CoV-2 evades interferon (IFN) activation in respiratory epithelial cells, resulting in a delayed response in bystander cells. Since pretreatment with IFNs can block viral infection, we reasoned that pharmacological activation of innate immune pathways could control SARS-CoV-2 infection. To identify potent antiviral innate immune agonists, we screened a panel of 75 microbial ligands that activate diverse signaling pathways and identified cyclic dinucleotides (CDNs), canonical STING agonists, as antiviral. Since CDNs have poor bioavailability, we tested the small molecule STING agonist diABZI, and found that it potently inhibits SARS-CoV-2 infection of diverse strains including variants of concern (B.1.351) by transiently stimulating IFN signaling. Importantly, diABZI restricts viral replication in primary human bronchial epithelial cells and in mice in vivo. Our study provides evidence that activation of STING may represent a promising therapeutic strategy to control SARS-CoV-2.


Subject(s)
Antiviral Agents/pharmacology , Benzimidazoles/pharmacology , COVID-19/prevention & control , Interferons/immunology , Membrane Proteins/agonists , Animals , Cell Line , Chlorocebus aethiops , Enzyme Activation/drug effects , Epithelial Cells/virology , Humans , Immune Evasion/immunology , Immunity, Innate/drug effects , Immunity, Innate/immunology , Mice , Mice, Inbred C57BL , Mice, Transgenic , SARS-CoV-2/growth & development , SARS-CoV-2/immunology , Vero Cells , Virus Replication/drug effects
3.
Sci Immunol ; 6(59)2021 05 18.
Article in English | MEDLINE | ID: covidwho-1234280

ABSTRACT

Coronaviruses are a family of RNA viruses that cause acute and chronic diseases of the upper and lower respiratory tract in humans and other animals. SARS-CoV-2 is a recently emerged coronavirus that has led to a global pandemic causing a severe respiratory disease known as COVID-19 with significant morbidity and mortality worldwide. The development of antiviral therapeutics are urgently needed while vaccine programs roll out worldwide. Here we describe a diamidobenzimidazole compound, diABZI-4, that activates STING and is highly effective in limiting SARS-CoV-2 replication in cells and animals. diABZI-4 inhibited SARS-CoV-2 replication in lung epithelial cells. Administration of diABZI-4 intranasally before or even after virus infection conferred complete protection from severe respiratory disease in K18-ACE2-transgenic mice infected with SARS-CoV-2. Intranasal delivery of diABZI-4 induced a rapid short-lived activation of STING, leading to transient proinflammatory cytokine production and lymphocyte activation in the lung associated with inhibition of viral replication. Our study supports the use of diABZI-4 as a host-directed therapy which mobilizes antiviral defenses for the treatment and prevention of COVID-19.


Subject(s)
Antiviral Agents/pharmacology , Benzimidazoles/pharmacology , COVID-19/drug therapy , COVID-19/prevention & control , Membrane Proteins/agonists , SARS-CoV-2/drug effects , A549 Cells , Animals , CD8-Positive T-Lymphocytes/immunology , Cell Line , Chlorocebus aethiops , Enzyme Activation/drug effects , Epithelial Cells/virology , Female , Humans , Killer Cells, Natural/immunology , Lymphocyte Activation/drug effects , Male , Membrane Proteins/metabolism , Mice , Mice, Knockout , SARS-CoV-2/growth & development , Vero Cells , Virus Replication/drug effects
4.
Antiviral Res ; 187: 105015, 2021 03.
Article in English | MEDLINE | ID: covidwho-1023450

ABSTRACT

The newly emerged severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) coronavirus initiated a pneumonia outbreak (COVID-19) that rapidly spread worldwide and quickly became a public health emergency of international concern; However to date, except Remdesivir, there are no clinically approved specific or effective medicines to prevent or treat COVID-19. Therefore, the development of novel treatments against coronavirus infections caused by the current SARS-CoV-2 virus, as well as other highly pathogenic human coronaviruses, represents an urgent unmet need. Stimulator of interferon genes (STING) plays a central role in host defense mechanisms against microbial infections. STING activation leads to the induction of both type I interferon and autophagy responses, which elicit strong inhibitory effect against the infections caused by a broad range of microbial pathogens. However, whether STING activation can impact infections from SARS-CoV-2 or other coronaviruses remains largely unknown. In this study, we investigated the anti-coronavirus activity triggered by STING activation. We discovered that dimeric amidobenzimidazole (diABZI), a synthetic small molecule STING receptor agonist, showed potent anti-coronavirus activity against both the common cold human coronavirus 229E (HCoV-229E) and SARS-CoV-2 in cell culture systems. In addition, we demonstrated that the antiviral activity of diABZI was dependent on the interferon pathway in HCoV-229E infected normal human fibroblast lung cells (MRC-5) and reconstituted primary human airway air-liquid interface (ALI) cultures. Furthermore, low-dose of diABZI treatment at 0.1 µM effectively reduced the SARS-CoV-2 viral load at the epithelial apical surface and prevented epithelial damage in the reconstituted primary human bronchial airway epithelial ALI system. Our findings have thus revealed the therapeutic potential of STING agonists, such as diABZI, as treatments for SARS-CoV-2 and other human coronavirus infections.


Subject(s)
Antiviral Agents/pharmacology , Benzimidazoles/pharmacology , COVID-19/drug therapy , Coronavirus 229E, Human/drug effects , Coronavirus Infections/drug therapy , Membrane Proteins/agonists , SARS-CoV-2/drug effects , Adenosine Monophosphate/analogs & derivatives , Adenosine Monophosphate/pharmacology , Alanine/analogs & derivatives , Alanine/pharmacology , Antiviral Agents/chemistry , Autophagy/drug effects , Bronchi/virology , COVID-19/virology , Cell Line , Coronavirus Infections/virology , Epithelial Cells/virology , Humans , Interferon Type I/pharmacology , Lung/virology , Virus Replication
5.
Chem Commun (Camb) ; 57(4): 504-507, 2021 Jan 14.
Article in English | MEDLINE | ID: covidwho-983835

ABSTRACT

A novel STING agonist, CDGSF, ipsilaterally modified with phosphorothioate and fluorine, was synthesized. The phosphorothioate in CDGSF might be a site for covalent conjugation. Injection of CDGSF generated an immunogenic ("hot") tumor microenvironment to suppress melanoma, more efficiently than dithio CDG. In particular, immunization with SARS-CoV-2 spike protein using CDGSF as an adjuvant elicited an exceptionally high antibody titer and a robust T cell response, overcoming the drawbacks of aluminum hydroxide. These results highlighted the therapeutic potential of CDGSF for cancer immunotherapy and the adjuvant potential of the STING agonist in the SARS-CoV-2 vaccine for the first time.


Subject(s)
Adjuvants, Immunologic/administration & dosage , COVID-19 Vaccines/administration & dosage , COVID-19/prevention & control , Melanoma, Experimental/drug therapy , Membrane Proteins/agonists , Nucleotides, Cyclic/administration & dosage , Skin Neoplasms/drug therapy , Adjuvants, Immunologic/chemical synthesis , Aluminum Hydroxide/administration & dosage , Aluminum Hydroxide/chemistry , Animals , Antibodies, Viral/biosynthesis , B-Lymphocytes/drug effects , B-Lymphocytes/immunology , B-Lymphocytes/virology , COVID-19/immunology , COVID-19/virology , COVID-19 Vaccines/chemistry , Enzyme-Linked Immunospot Assay , Humans , Immunotherapy/methods , Interferon-gamma/biosynthesis , Melanoma, Experimental/immunology , Melanoma, Experimental/mortality , Melanoma, Experimental/pathology , Membrane Proteins/genetics , Membrane Proteins/immunology , Mice , Nucleotides, Cyclic/chemical synthesis , SARS-CoV-2/drug effects , SARS-CoV-2/immunology , SARS-CoV-2/pathogenicity , Skin Neoplasms/immunology , Skin Neoplasms/mortality , Skin Neoplasms/pathology , Spike Glycoprotein, Coronavirus/administration & dosage , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology , Survival Analysis , T-Lymphocytes/drug effects , T-Lymphocytes/immunology , T-Lymphocytes/virology , Tumor Burden/drug effects , Tumor Microenvironment/drug effects , Tumor Microenvironment/immunology , Vaccination/methods
6.
Antiviral Res ; 183: 104933, 2020 11.
Article in English | MEDLINE | ID: covidwho-773873

ABSTRACT

Stimulator of interferon genes (STING), as a signaling hub in innate immunity, plays a central role for the effective initiation of host defense mechanisms against microbial infections. Upon binding of its ligand cyclic dinucleotides (CDNs) produced by the cyclic GMP-AMP synthase (cGAS) or invading bacteria, STING is activated, leading to the induction of both type I interferon responses and autophagy, which are critical for the control of certain microbial infections. RNA viruses, such as Parainfluenza virus (PIV) and Rhinovirus (HRV), are among the leading causes of respiratory infections that affect human health without effective treatments. Activation of STING pathway may provide a new therapeutic approach fighting against these viruses. However, the role of STING in the control of RNA virus infection remains largely unexplored. In this study, using dimeric amidobenzimidazole (diABZI), a newly discovered synthetic small molecule STING receptor agonist with much higher potency than CDNs, we found that activation of STING elicits potent antiviral effects against parainfluenza virus type 3 (PIV3) and human rhinovirus 16 (HRV16), two representative respiratory viral pathogens. Notably, while anti-PIV3 activity was depend on the induction of type I interferon responses through TANK-binding kinase 1 (TBK1), anti-HRV16 activity required the induction of autophagy-related gene 5 (ATG5)-dependent autophagy, indicating that two distinct antiviral mechanisms are engaged upon STING activation. Antiviral activity and individual specific pathway was further confirmed in infected primary bronchial epithelial cells. Our findings thus demonstrate the distinct antiviral mechanisms triggered by STING agonist and uncover the potential of therapeutic effect against different viruses.


Subject(s)
Antiviral Agents/pharmacology , Membrane Proteins/agonists , Parainfluenza Virus 3, Human/drug effects , Rhinovirus/drug effects , Signal Transduction/drug effects , Virus Replication/drug effects , Animals , Antiviral Agents/chemical synthesis , Autophagy , Cell Line , Cells, Cultured , HeLa Cells , Humans , Immunity, Innate , Mice , Parainfluenza Virus 3, Human/physiology , RAW 264.7 Cells , Rhinovirus/physiology , Signal Transduction/immunology , THP-1 Cells
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