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1.
Cell ; 185(8): 1389-1401.e18, 2022 Apr 14.
Article in English | MEDLINE | ID: covidwho-1788017

ABSTRACT

The effectiveness of SARS-CoV-2 vaccines and therapeutic antibodies have been limited by the continuous emergence of viral variants and by the restricted diffusion of antibodies from circulation into the sites of respiratory virus infection. Here, we report the identification of two highly conserved regions on the Omicron variant receptor-binding domain recognized by broadly neutralizing antibodies. Furthermore, we generated a bispecific single-domain antibody that was able to simultaneously and synergistically bind these two regions on a single Omicron variant receptor-binding domain as revealed by cryo-EM structures. We demonstrated that this bispecific antibody can be effectively delivered to lung via inhalation administration and exhibits exquisite neutralization breadth and therapeutic efficacy in mouse models of SARS-CoV-2 infections. Importantly, this study also deciphered an uncommon and highly conserved cryptic epitope within the spike trimeric interface that may have implications for the design of broadly protective SARS-CoV-2 vaccines and therapeutics.

2.
Viruses ; 14(4):655, 2022.
Article in English | MDPI | ID: covidwho-1753696

ABSTRACT

The coronavirus disease 2019 (COVID-19) pandemic caused by infection of SARS-CoV-2 and its variants has posed serious threats to global public health, thus calling for the development of potent and broad-spectrum antivirals. We previously designed and developed a peptide-based pan-coronavirus (CoV) fusion inhibitor, EK1, which is effective against all human CoVs (HCoV) tested by targeting the HCoV S protein HR1 domain. However, its relatively short half-life may limit its clinical use. Therefore, we designed, constructed, and expressed a recombinant protein, FL-EK1, which consists of a modified fibronectin type III domain (FN3) with albumin-binding capacity, a flexible linker, and EK1. As with EK1, we found that FL-EK1 could also effectively inhibit infection of SARS-CoV-2 and its variants, as well as HCoV-OC43. Furthermore, it protected mice from infection by the SARS-CoV-2 Delta variant and HCoV-OC43. Importantly, the half-life of FL-EK1 (30 h) is about 15.7-fold longer than that of EK1 (1.8 h). These results suggest that FL-EK1 is a promising candidate for the development of a pan-CoV fusion inhibitor-based long-acting antiviral drug for preventing and treating infection by current and future SARS-CoV-2 variants, as well as other HCoVs.

3.
Viruses ; 14(3)2022 03 13.
Article in English | MEDLINE | ID: covidwho-1742726

ABSTRACT

The prolonged duration of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic has resulted in the continuous emergence of variants of concern (VOC, e.g., Omicron) and variants of interest (VOI, e.g., Lambda). These variants have challenged the protective efficacy of current COVID-19 vaccines, thus calling for the development of novel therapeutics against SARS-CoV-2 and its VOCs. Here, we constructed a novel fusion inhibitor-based recombinant protein, denoted as 5-Helix, consisting of three heptad repeat 1 (HR1) and two heptad repeat 2 (HR2) fragments. The 5-Helix interacted with the HR2 domain of the viral S2 subunit, the most conserved region in spike (S) protein, to block homologous six-helix bundle (6-HB) formation between viral HR1 and HR2 domains and, hence, viral S-mediated cell-cell fusion. The 5-Helix potently inhibited infection by pseudotyped SARS-CoV-2 and its VOCs, including Delta and Omicron variants. The 5-Helix also inhibited infection by authentic SARS-CoV-2 wild-type (nCoV-SH01) strain and its Delta variant. Collectively, our findings suggest that 5-Helix can be further developed as either a therapeutic or prophylactic to treat and prevent infection by SARS-CoV-2 and its variants.


Subject(s)
COVID-19 , Viral Envelope Proteins , COVID-19 Vaccines , Humans , Membrane Glycoproteins/metabolism , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics , Viral Envelope Proteins/metabolism
4.
Viruses ; 14(3)2022 03 06.
Article in English | MEDLINE | ID: covidwho-1732247

ABSTRACT

Our previous studies have shown that cholesterol-conjugated, peptide-based pan-coronavirus (CoV) fusion inhibitors can potently inhibit human CoV infection. However, only palmitic acid (C16)-based lipopeptide drugs have been tested clinically, suggesting that the development of C16-based lipopeptide drugs is feasible. Here, we designed and synthesized a C16-modified pan-CoV fusion inhibitor, EK1-C16, and found that it potently inhibited infection by SARS-CoV-2 and its variants of concern (VOCs), including Omicron, and other human CoVs and bat SARS-related CoVs (SARSr-CoVs). These results suggest that EK1-C16 could be further developed for clinical use to prevent and treat infection by the currently circulating MERS-CoV, SARS-CoV-2 and its VOCs, as well as any future emerging or re-emerging coronaviruses.


Subject(s)
COVID-19 , Middle East Respiratory Syndrome Coronavirus , COVID-19/drug therapy , Humans , Lipopeptides/pharmacology , Palmitic Acid/pharmacology , SARS-CoV-2
6.
Viruses ; 14(3)2022 02 28.
Article in English | MEDLINE | ID: covidwho-1715781

ABSTRACT

The global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become more serious because of the continuous emergence of variants of concern (VOC), thus calling for the development of broad-spectrum vaccines with greater efficacy. Adjuvants play important roles in enhancing the immunogenicity of protein-based subunit vaccines. In this study, we compared the effect of three adjuvants, including aluminum, nanoparticle manganese and MF59, on the immunogenicity of three protein-based COVID-19 vaccine candidates, including RBD-Fc, RBD and S-trimer. We found that the nanoparticle manganese adjuvant elicited the highest titers of SARS-CoV-2 RBD-specific IgG, IgG1 and IgG2a, as well as neutralizing antibodies against infection by pseudotyped SARS-CoV-2 and its Delta variant. What is more, the nanoparticle manganese adjuvant effectively reduced the viral load of the authentic SARS-CoV-2 and Delta variant in the cell culture supernatants. These results suggest that nanoparticle manganese, known to facilitate cGAS-STING activation, is an optimal adjuvant for protein-based COVID-19 subunit vaccines.


Subject(s)
COVID-19 , Viral Vaccines , Animals , COVID-19/prevention & control , COVID-19 Vaccines , Humans , Immunity , Mice , Mice, Inbred BALB C , SARS-CoV-2 , Vaccines, Subunit
7.
Viruses ; 14(3)2022 02 27.
Article in English | MEDLINE | ID: covidwho-1715777

ABSTRACT

In recent years, infectious diseases caused by viral infections have seriously endangered human health, especially COVID-19, caused by SARS-CoV-2, which continues to spread worldwide. The development of broad-spectrum antiviral inhibitors is urgently needed. Here, we report a series of small-molecule compounds that proved effective against human coronaviruses (HCoV), such as SARS-CoV-2 and its variants of concern (VOCs), including Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), and Omicron (B.1.1.529), SARS-CoV, MERS-CoV, HCoV-OC43, and other viruses with class I viral fusion proteins, such as influenza virus, Ebola virus (EBOV), Nipah virus (NiV), and Lassa fever virus (LASV). They are also effective against class II enveloped viruses represented by ZIKV and class III enveloped viruses represented by vesicular stomatitis virus (VSV). Further studies have shown that these compounds may exert antiviral effects through a variety of mechanisms, including inhibiting the formation of the six-helix bundle, which is a typical feature of enveloped virus fusion with cell membranes, and/or targeting viral membrane to inactivate cell-free virions. These compounds are expected to become drug candidates against SARS-CoV-2 and other enveloped viruses.


Subject(s)
COVID-19 , Rhodanine , Zika Virus Infection , Zika Virus , COVID-19/drug therapy , Humans , SARS-CoV-2
8.
Trends Immunol ; 43(3): 170-172, 2022 03.
Article in English | MEDLINE | ID: covidwho-1712717

ABSTRACT

The concurrent prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and Middle East respiratory syndrome coronavirus (MERS-CoV) raises the concern for the emergence of potential new ß-CoV clades via genetic recombination, bearing high SARS-CoV-2-like transmissibility and high MERS-CoV-like mortality rates. Therefore, we argue that there is an urgent need to develop pan-ß-CoV vaccines that can target not only current SARS-CoV-2 variants of concern, but also future putative SARS-CoV-3- or MERS-CoV-2-like coronavirus.


Subject(s)
COVID-19 , Vaccines , COVID-19/prevention & control , COVID-19 Vaccines , Humans , SARS-CoV-2
10.
EuropePMC; 2020.
Preprint in English | EuropePMC | ID: ppcovidwho-315723

ABSTRACT

The pandemic of COVID-19 caused by SARS-CoV-2 has posed serious threats to global health and economy, thus calling for the development of safe and effective vaccines. The receptor-binding domain (RBD) in the spike protein of SARS-CoV-2 is responsible for its binding to ACE2 receptor. It contains multiple dominant neutralizing epitopes and serves as an important antigen for the development of COVID-19 vaccines. Here, we showed that immunization of mice with a candidate subunit vaccine consisting of SARS-CoV-2 RBD and Fc fragment of human IgG, as an immunopotentiator, elicited high titer of RBD-specific antibodies with robust neutralizing activity against both pseudotyped and live SARS-CoV-2 infections. The mouse antisera could also effectively neutralize infection by pseudotyped SARS-CoV-2 with several natural mutations in RBD and the IgG extracted from the mouse antisera could also show neutralization against pseudotyped SARS-CoV and SARS-related coronavirus (SARSr-CoV). Vaccination of human ACE2 transgenic mice with RBD-Fc could effectively protect mice from the SARS-CoV-2 challenge. These results suggest that SARS-CoV-2 RBD-Fc has good potential to be further developed as an effective and broad-spectrum vaccine to prevent infection of the current SARS-CoV-2 and its mutants, as well as future emerging SARSr-CoVs and re-emerging SARS-CoV.

11.
Viruses ; 14(2)2022 02 14.
Article in English | MEDLINE | ID: covidwho-1687054

ABSTRACT

Several countries have made unremitting efforts to develop an optimal vaccine in the fight against coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). With the increasing occurrence of SARS-CoV-2 variants, current vaccines show decreased neutralizing activities, especially towards the Omicron variant. In this context, adding appropriate adjuvants to COVID-19 vaccines can substantially reduce the number of required doses and improve efficacy or cross-neutralizing protection. We mainly focus on research progress and achievements associated with adjuvanted COVID-19 subunit and inactivated vaccines. We further compare the advantages and disadvantages of different adjuvant formulations in order to provide a scientific reference for designing an effective strategy for future vaccine development.


Subject(s)
Adjuvants, Immunologic/administration & dosage , Adjuvants, Immunologic/analysis , COVID-19 Vaccines/immunology , SARS-CoV-2/immunology , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/prevention & control , COVID-19 Vaccines/analysis , Humans , Vaccines, Inactivated
13.
Cell Res ; 32(3): 269-287, 2022 03.
Article in English | MEDLINE | ID: covidwho-1634806

ABSTRACT

The emergence of SARS-CoV-2 variants and potentially other highly pathogenic sarbecoviruses in the future highlights the need for pan-sarbecovirus vaccines. Here, we discovered a new STING agonist, CF501, and found that CF501-adjuvanted RBD-Fc vaccine (CF501/RBD-Fc) elicited significantly stronger neutralizing antibody (nAb) and T cell responses than Alum- and cGAMP-adjuvanted RBD-Fc in mice. Vaccination of rabbits and rhesus macaques (nonhuman primates, NHPs) with CF501/RBD-Fc elicited exceptionally potent nAb responses against SARS-CoV-2 and its nine variants and 41 S-mutants, SARS-CoV and bat SARSr-CoVs. CF501/RBD-Fc-immunized hACE2-transgenic mice were almost completely protected against SARS-CoV-2 challenge, even 6 months after the initial immunization. NHPs immunized with a single dose of CF501/RBD-Fc produced high titers of nAbs. The immunized macaques also exhibited durable humoral and cellular immune responses and showed remarkably reduced viral load in the upper and lower airways upon SARS-CoV-2 challenge even at 108 days post the final immunization. Thus, CF501/RBD-Fc can be further developed as a novel pan-sarbecovirus vaccine to combat current and future outbreaks of sarbecovirus diseases.


Subject(s)
COVID-19 , Vaccines , Animals , Antibodies, Neutralizing , Antibodies, Viral , COVID-19/prevention & control , COVID-19 Vaccines , Macaca mulatta , Mice , Rabbits , SARS-CoV-2 , Spike Glycoprotein, Coronavirus , T-Lymphocytes
14.
Emerg Microbes Infect ; 11(1): 477-481, 2022 Dec.
Article in English | MEDLINE | ID: covidwho-1625890

ABSTRACT

The massive and rapid transmission of SARS-CoV-2 has led to the emergence of several viral variants of concern (VOCs), with the most recent one, B.1.1.529 (Omicron), which accumulated a large number of spike mutations, raising the specter that this newly identified variant may escape from the currently available vaccines and therapeutic antibodies. Using VSV-based pseudovirus, we found that Omicron variant is markedly resistant to neutralization of sera from convalescents or individuals vaccinated by two doses of inactivated whole-virion vaccines (BBIBP-CorV). However, a homologous inactivated vaccine booster or a heterologous booster with protein subunit vaccine (ZF2001) significantly increased neutralization titers to both WT and Omicron variant. Moreover, at day 14 post the third dose, neutralizing antibody titer reduction for Omicron was less than that for convalescents or individuals who had only two doses of the vaccine, indicating that a homologous or heterologous booster can reduce the Omicron escape from neutralizing. In addition, we tested a panel of 17 SARS-CoV-2 monoclonal antibodies (mAbs). Omicron resists seven of eight authorized/approved mAbs, as well as most of the other mAbs targeting distinct epitopes on RBD and NTD. Taken together, our results suggest the urgency to push forward the booster vaccination to combat the emerging SARS-CoV-2 variants.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19 Vaccines/immunology , COVID-19/prevention & control , Immunization, Secondary , SARS-CoV-2/immunology , Vaccines, Inactivated/immunology , Antibodies, Monoclonal/immunology , COVID-19 Vaccines/administration & dosage , Epitopes/immunology , Humans , Neutralization Tests , Spike Glycoprotein, Coronavirus/immunology , Vaccination , Vaccines, Inactivated/administration & dosage
15.
Curr Opin Virol ; 53: 101199, 2021 Dec 30.
Article in English | MEDLINE | ID: covidwho-1588012

ABSTRACT

The pandemic of Coronavirus Disease 2019 (COVID-19) caused by severe acute respiratory syndrome 2 coronavirus (SARS-CoV-2) is a continuing worldwide threat to human health and social economy. Historically, SARS-CoV-2 follows SARS and MERS as the third coronavirus spreading across borders and continents, but far more dangerous with long-lasting symptomatic consequences. The current situation is strong evidence that coronaviruses will continue to be pathogens of consequence in the future, thus calling for the development of neutralizing antibody-based prophylactics and therapeutics for prevention and treatment of COVID-19 and other human coronavirus diseases. This review summarized the progresses of developing neutralizing monoclonal antibodies against infection of SARS-CoV-2, SARS-CoV, and MERS-CoV, and discussed their potential applications in prevention and treatment of COVID-19 and other human coronavirus diseases.

18.
Signal Transduct Target Ther ; 6(1): 378, 2021 11 03.
Article in English | MEDLINE | ID: covidwho-1500450

ABSTRACT

The current COVID-19 pandemic has heavily burdened the global public health system and may keep simmering for years. The frequent emergence of immune escape variants have spurred the search for prophylactic vaccines and therapeutic antibodies that confer broad protection against SARS-CoV-2 variants. Here we show that the bivalency of an affinity maturated fully human single-domain antibody (n3113.1-Fc) exhibits exquisite neutralizing potency against SARS-CoV-2 pseudovirus, and confers effective prophylactic and therapeutic protection against authentic SARS-CoV-2 in the host cell receptor angiotensin-converting enzyme 2 (ACE2) humanized mice. The crystal structure of n3113 in complex with the receptor-binding domain (RBD) of SARS-CoV-2, combined with the cryo-EM structures of n3113 and spike ecto-domain, reveals that n3113 binds to the side surface of up-state RBD with no competition with ACE2. The binding of n3113 to this novel epitope stabilizes spike in up-state conformations but inhibits SARS-CoV-2 S mediated membrane fusion, expanding our recognition of neutralization by antibodies against SARS-CoV-2. Binding assay and pseudovirus neutralization assay show no evasion of recently prevalent SARS-CoV-2 lineages, including Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), and Delta (B.1.617.2) for n3113.1-Fc with Y58L mutation, demonstrating the potential of n3113.1-Fc (Y58L) as a promising candidate for clinical development to treat COVID-19.


Subject(s)
Angiotensin-Converting Enzyme 2/chemistry , Antibodies, Neutralizing/chemistry , Antibodies, Viral/chemistry , COVID-19 , SARS-CoV-2/chemistry , Single-Chain Antibodies/chemistry , Angiotensin-Converting Enzyme 2/immunology , Animals , Antibodies, Neutralizing/immunology , Antibodies, Neutralizing/therapeutic use , Antibodies, Viral/immunology , Antibodies, Viral/therapeutic use , Crystallography, X-Ray , Epitopes/chemistry , Epitopes/immunology , Humans , Mice , SARS-CoV-2/immunology , Single-Chain Antibodies/immunology , Single-Chain Antibodies/therapeutic use
19.
Int J Mol Sci ; 22(21)2021 Nov 01.
Article in English | MEDLINE | ID: covidwho-1488619

ABSTRACT

The COVID-19 pandemic caused by SARS-CoV-2 infection poses a serious threat to global public health and the economy. The enzymatic product of cholesterol 25-hydroxylase (CH25H), 25-Hydroxycholesterol (25-HC), was reported to have potent anti-SARS-CoV-2 activity. Here, we found that the combination of 25-HC with EK1 peptide, a pan-coronavirus (CoV) fusion inhibitor, showed a synergistic antiviral activity. We then used the method of 25-HC modification to design and synthesize a series of 25-HC-modified peptides and found that a 25-HC-modified EK1 peptide (EK1P4HC) was highly effective against infections caused by SARS-CoV-2, its variants of concern (VOCs), and other human CoVs, such as HCoV-OC43 and HCoV-229E. EK1P4HC could protect newborn mice from lethal HCoV-OC43 infection, suggesting that conjugation of 25-HC with a peptide-based viral inhibitor was a feasible and universal strategy to improve its antiviral activity.


Subject(s)
Antiviral Agents/pharmacology , Hydroxycholesterols/chemistry , Lipopeptides/chemistry , SARS-CoV-2/drug effects , Amino Acid Sequence , Animals , Antiviral Agents/chemistry , Antiviral Agents/therapeutic use , Body Weight/drug effects , COVID-19/drug therapy , COVID-19/virology , Coronavirus 229E, Human/drug effects , Coronavirus 229E, Human/pathogenicity , Coronavirus Infections/drug therapy , Coronavirus Infections/mortality , Coronavirus Infections/virology , Coronavirus OC43, Human/drug effects , Coronavirus OC43, Human/pathogenicity , Disease Models, Animal , Drug Synergism , Humans , Hydroxycholesterols/pharmacology , Hydroxycholesterols/therapeutic use , Lipopeptides/pharmacology , Lipopeptides/therapeutic use , Mice , Mice, Inbred BALB C , Polyethylene Glycols/chemistry , SARS-CoV-2/isolation & purification , SARS-CoV-2/physiology , Survival Rate , Virus Internalization/drug effects
20.
Protein Cell ; 2021 Sep 23.
Article in English | MEDLINE | ID: covidwho-1432661

ABSTRACT

New threats posed by the emerging circulating variants of SARS-CoV-2 highlight the need to find conserved neutralizing epitopes for therapeutic antibodies and efficient vaccine design. Here, we identified a receptor-binding domain (RBD)-binding antibody, XG014, which potently neutralizes ß-coronavirus lineage B (ß-CoV-B), including SARS-CoV-2, its circulating variants, SARS-CoV and bat SARSr-CoV WIV1. Interestingly, antibody family members competing with XG014 binding show reduced levels of cross-reactivity and induce antibody-dependent SARS-CoV-2 spike (S) protein-mediated cell-cell fusion, suggesting a unique mode of recognition by XG014. Structural analyses reveal that XG014 recognizes a conserved epitope outside the ACE2 binding site and completely locks RBD in the non-functional "down" conformation, while its family member XG005 directly competes with ACE2 binding and position the RBD "up". Single administration of XG014 is effective in protection against and therapy of SARS-CoV-2 infection in vivo. Our findings suggest the potential to develop XG014 as pan-ß-CoV-B therapeutics and the importance of the XG014 conserved antigenic epitope for designing broadly protective vaccines against ß-CoV-B and newly emerging SARS-CoV-2 variants of concern.

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