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Liang Z, Tong J, Wu X, Liu S, Wu J, Yu Y, Zhang L, Zhao C, Lu Q, Nie J, Huang W, Wang Y. Development of a SARS-CoV-2 neutralization assay based on a pseudotyped virus using a HIV system. MedComm (Beijing) 2024; 5:e517. [PMID: 38525106 PMCID: PMC10959455 DOI: 10.1002/mco2.517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 02/06/2024] [Accepted: 02/25/2024] [Indexed: 03/26/2024] Open
Abstract
Regarding the extensive global attention to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that constitutes an international public health emergency, pseudovirus neutralization assays have been widely applied due to their advantages of being able to be conducted in biosafety level 2 laboratories and having a high safety factor. In this study, by adding a blue fluorescent protein (AmCyan) gene to the HIV system pSG3-△env backbone plasmid HpaI and truncating the C-terminal 21 amino acids of the SARS-CoV-2 spike protein (S), high-titer SARS-CoV-2-Sdel21-AmCyan fluorescent pseudovirus was successfully packaged. The fluorescent pseudovirus was used to establish a neutralization assay in a 96-well plate using 293T cells stably transfected with the AF cells. Then, parameters such as the ratio of backbone and membrane plasmid, sensitive cells, inoculation of cells and virus, as well as incubation and detection time were optimized. The pseudovirus neutralization assay demonstrated high accuracy, sensitivity, repeatability, and a strong correlation with the luminescent pseudovirus neutralization assay. Additionally, we scaled up the neutralizing antibody determination method by increasing the plate size from 96 wells to 384 wells. We have established a robust fluorescent pseudotyped virus neutralization assay for SARS-CoV-2 using the HIV system, providing a foundation for serum neutralization antibody detection, monoclonal antibody screening, and vaccine development.
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Affiliation(s)
- Ziteng Liang
- Chinese Academy of Medical Sciences & Peking Union Medical CollegeDongcheng District, BeijingChina
- Division of HIV/AIDS and Sex‐transmitted Virus Vaccines, Institute for Biological Product Control, National Institutes for Food and Drug Control (NIFDC), WHO Collaborating Center for Standardization and Evaluation of BiologicalsNHC Key Laboratory of Research on Quality and Standardization of Biotech Products and NMPA Key Laboratory for Quality Research and Evaluation of Biological ProductsBeijingChina
| | - Jincheng Tong
- Division of HIV/AIDS and Sex‐transmitted Virus Vaccines, Institute for Biological Product Control, National Institutes for Food and Drug Control (NIFDC), WHO Collaborating Center for Standardization and Evaluation of BiologicalsNHC Key Laboratory of Research on Quality and Standardization of Biotech Products and NMPA Key Laboratory for Quality Research and Evaluation of Biological ProductsBeijingChina
| | - Xi Wu
- Division of HIV/AIDS and Sex‐transmitted Virus Vaccines, Institute for Biological Product Control, National Institutes for Food and Drug Control (NIFDC), WHO Collaborating Center for Standardization and Evaluation of BiologicalsNHC Key Laboratory of Research on Quality and Standardization of Biotech Products and NMPA Key Laboratory for Quality Research and Evaluation of Biological ProductsBeijingChina
| | - Shuo Liu
- Changping LaboratoryChangping District, BeijingChina
| | - Jiajing Wu
- Beijing Yunling Biotechnology Co., Ltd.BeijingChina
| | - Yuanling Yu
- Changping LaboratoryChangping District, BeijingChina
| | - Li Zhang
- Division of HIV/AIDS and Sex‐transmitted Virus Vaccines, Institute for Biological Product Control, National Institutes for Food and Drug Control (NIFDC), WHO Collaborating Center for Standardization and Evaluation of BiologicalsNHC Key Laboratory of Research on Quality and Standardization of Biotech Products and NMPA Key Laboratory for Quality Research and Evaluation of Biological ProductsBeijingChina
| | - Chenyan Zhao
- Division of HIV/AIDS and Sex‐transmitted Virus Vaccines, Institute for Biological Product Control, National Institutes for Food and Drug Control (NIFDC), WHO Collaborating Center for Standardization and Evaluation of BiologicalsNHC Key Laboratory of Research on Quality and Standardization of Biotech Products and NMPA Key Laboratory for Quality Research and Evaluation of Biological ProductsBeijingChina
| | - Qiong Lu
- Division of HIV/AIDS and Sex‐transmitted Virus Vaccines, Institute for Biological Product Control, National Institutes for Food and Drug Control (NIFDC), WHO Collaborating Center for Standardization and Evaluation of BiologicalsNHC Key Laboratory of Research on Quality and Standardization of Biotech Products and NMPA Key Laboratory for Quality Research and Evaluation of Biological ProductsBeijingChina
| | - Jianhui Nie
- Division of HIV/AIDS and Sex‐transmitted Virus Vaccines, Institute for Biological Product Control, National Institutes for Food and Drug Control (NIFDC), WHO Collaborating Center for Standardization and Evaluation of BiologicalsNHC Key Laboratory of Research on Quality and Standardization of Biotech Products and NMPA Key Laboratory for Quality Research and Evaluation of Biological ProductsBeijingChina
| | - Weijin Huang
- Division of HIV/AIDS and Sex‐transmitted Virus Vaccines, Institute for Biological Product Control, National Institutes for Food and Drug Control (NIFDC), WHO Collaborating Center for Standardization and Evaluation of BiologicalsNHC Key Laboratory of Research on Quality and Standardization of Biotech Products and NMPA Key Laboratory for Quality Research and Evaluation of Biological ProductsBeijingChina
| | - Youchun Wang
- Chinese Academy of Medical Sciences & Peking Union Medical CollegeDongcheng District, BeijingChina
- Division of HIV/AIDS and Sex‐transmitted Virus Vaccines, Institute for Biological Product Control, National Institutes for Food and Drug Control (NIFDC), WHO Collaborating Center for Standardization and Evaluation of BiologicalsNHC Key Laboratory of Research on Quality and Standardization of Biotech Products and NMPA Key Laboratory for Quality Research and Evaluation of Biological ProductsBeijingChina
- Changping LaboratoryChangping District, BeijingChina
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Letko M. Functional assessment of cell entry and receptor use for merbecoviruses. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.13.584892. [PMID: 38559009 PMCID: PMC10980018 DOI: 10.1101/2024.03.13.584892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
The merbecovirus subgenus of coronaviruses includes Middle East Respiratory Syndrome Coronavirus (MERS-CoV), which is a zoonotic respiratory pathogen that transmits from dromedary camels to humans and causes severe respiratory disease. Viral discovery efforts have uncovered hundreds of merbecoviruses in different species across multiple continents, but few of these viruses have been isolated or studied under laboratory conditions, leaving basic questions regarding their threat to humans unresolved. Viral entry into host cells is considered an early and critical step for transmission between hosts. In this study, a scalable approach to assessing novel merbecovirus cell entry was developed and used to measure receptor use across the entire merbecovirus subgenus. Merbecoviruses are sorted into four clades based on the receptor binding domain of the spike glycoprotein. Receptor tropism is clade-specific, with only one clade using DPP4 and multiple clades using ACE2, including the entire HKU5 cluster of bat coronaviruses.
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Affiliation(s)
- Michael Letko
- Paul G. Allen School for Global Health, Washington State University, Pullman, WA, 99163
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3
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Lu A, Ebright B, Naik A, Tan HL, Cohen NA, Bouteiller JMC, Lazzi G, Louie SG, Humayun MS, Asante I. Hydroxypropyl-Beta Cyclodextrin Barrier Prevents Respiratory Viral Infections: A Preclinical Study. Int J Mol Sci 2024; 25:2061. [PMID: 38396738 PMCID: PMC10888609 DOI: 10.3390/ijms25042061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 02/05/2024] [Accepted: 02/06/2024] [Indexed: 02/25/2024] Open
Abstract
The emergence and mutation of pathogenic viruses have been occurring at an unprecedented rate in recent decades. The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has developed into a global public health crisis due to extensive viral transmission. In situ RNA mapping has revealed angiotensin-converting enzyme 2 (ACE2) expression to be highest in the nose and lower in the lung, pointing to nasal susceptibility as a predominant route for infection and the cause of subsequent pulmonary effects. By blocking viral attachment and entry at the nasal airway using a cyclodextrin-based formulation, a preventative therapy can be developed to reduce viral infection at the site of entry. Here, we assess the safety and antiviral efficacy of cyclodextrin-based formulations. From these studies, hydroxypropyl beta-cyclodextrin (HPBCD) and hydroxypropyl gamma-cyclodextrin (HPGCD) were then further evaluated for antiviral effects using SARS-CoV-2 pseudotypes. Efficacy findings were confirmed with SARS-CoV-2 Delta variant infection of Calu-3 cells and using a K18-hACE2 murine model. Intranasal pre-treatment with HPBCD-based formulations reduced viral load and inflammatory signaling in the lung. In vitro efficacy studies were further conducted using lentiviruses, murine hepatitis virus (MHV), and influenza A virus subtype H1N1. These findings suggest HPBCD may be used as an agnostic barrier against transmissible pathogens, including but not limited to SARS-CoV-2.
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Affiliation(s)
- Angela Lu
- Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.L.); (B.E.); (A.N.); (S.G.L.)
| | - Brandon Ebright
- Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.L.); (B.E.); (A.N.); (S.G.L.)
| | - Aditya Naik
- Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.L.); (B.E.); (A.N.); (S.G.L.)
| | - Hui L. Tan
- Department of Otorhinolaryngology, Head and Neck Surgery, University of Pennsylvania, Philadelphia, PA 19104, USA; (H.L.T.); (N.A.C.)
| | - Noam A. Cohen
- Department of Otorhinolaryngology, Head and Neck Surgery, University of Pennsylvania, Philadelphia, PA 19104, USA; (H.L.T.); (N.A.C.)
- Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA 19104, USA
| | - Jean-Marie C. Bouteiller
- Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90007, USA; (J.-M.C.B.); (G.L.); (M.S.H.)
| | - Gianluca Lazzi
- Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90007, USA; (J.-M.C.B.); (G.L.); (M.S.H.)
- Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Stan G. Louie
- Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.L.); (B.E.); (A.N.); (S.G.L.)
| | - Mark S. Humayun
- Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90007, USA; (J.-M.C.B.); (G.L.); (M.S.H.)
- Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Isaac Asante
- Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.L.); (B.E.); (A.N.); (S.G.L.)
- Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
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4
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Xie M. Virus-Induced Cell Fusion and Syncytia Formation. Results Probl Cell Differ 2024; 71:283-318. [PMID: 37996683 DOI: 10.1007/978-3-031-37936-9_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
Most enveloped viruses encode viral fusion proteins to penetrate host cell by membrane fusion. Interestingly, many enveloped viruses can also use viral fusion proteins to induce cell-cell fusion, both in vitro and in vivo, leading to the formation of syncytia or multinucleated giant cells (MGCs). In addition, some non-enveloped viruses encode specialized viral proteins that induce cell-cell fusion to facilitate viral spread. Overall, viruses that can induce cell-cell fusion are nearly ubiquitous in mammals. Virus cell-to-cell spread by inducing cell-cell fusion may overcome entry and post-entry blocks in target cells and allow evasion of neutralizing antibodies. However, molecular mechanisms of virus-induced cell-cell fusion remain largely unknown. Here, I summarize the current understanding of virus-induced cell fusion and syncytia formation.
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Affiliation(s)
- Maorong Xie
- Division of Infection and Immunity, UCL, London, UK.
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5
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Beitari S, Agbayani G, Hewitt M, Duque D, Bavananthasivam J, Sandhu JK, Akache B, Hadžisejdić I, Tran A. Effectiveness of VSV vectored SARS-CoV-2 spike when administered through intranasal, intramuscular or a combination of both. Sci Rep 2023; 13:21390. [PMID: 38049498 PMCID: PMC10695950 DOI: 10.1038/s41598-023-48397-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 11/26/2023] [Indexed: 12/06/2023] Open
Abstract
A critical feature of the VSV vector platform is the ability to pseudotype the virus with different glycoproteins from other viruses, thus altering cellular tropism of the recombinant virus. The route of administration is critical in triggering local and systemic immune response and protection. Most of the vaccine platforms used at the forefront are administered by intramuscular injection. However, it is not known at what level ACE2 is expressed on the surface of skeletal muscle cells, which will have a significant impact on the efficiency of a VSV-SARS-CoV-2 spike vaccine to mount a protective immune response when administered intramuscularly. In this study, we investigate the immunogenicity and efficacy of a prime-boost immunization regimen administered intranasally (IN), intramuscularly (IM), or combinations of the two. We determined that the prime-boost combinations of IM followed by IN immunization (IM + IN) or IN followed by IN immunization (IN + IN) exhibited strong spike-specific IgG, IgA and T cell response in vaccinated K18 knock-in mice. Hamsters vaccinated with two doses of VSV expressing SARS-CoV-2 spike, both delivered by IN or IM + IN, showed strong protection against SARS-CoV-2 variants of concern Alpha and Delta. This protection was also observed in aged hamsters. Our study underscores the highly crucial role immunization routes have with the VSV vector platform to elicit a strong and protective immune response.
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Affiliation(s)
- Saina Beitari
- Infectious Diseases, Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON, Canada
| | - Gerard Agbayani
- Immunomodulation, Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON, Canada
| | - Melissa Hewitt
- Preclinical Imaging, Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON, Canada
| | - Diana Duque
- Infectious Diseases, Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON, Canada
| | - Jegarubee Bavananthasivam
- Infectious Diseases, Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON, Canada
| | - Jagdeep K Sandhu
- Preclinical Imaging, Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON, Canada
| | - Bassel Akache
- Immunomodulation, Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON, Canada
| | - Ita Hadžisejdić
- Clinical Department of Pathology and Cytology Clinical Hospital Center Rijeka, University of Rijeka, Rijeka, Croatia
| | - Anh Tran
- Infectious Diseases, Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON, Canada.
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6
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Llewellyn GN, Chen HY, Rogers GL, Huang X, Sell PJ, Henley JE, Cannon PM. Comparison of SARS-CoV-2 entry inhibitors based on ACE2 receptor or engineered Spike-binding peptides. J Virol 2023; 97:e0068423. [PMID: 37555663 PMCID: PMC10506483 DOI: 10.1128/jvi.00684-23] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 06/29/2023] [Indexed: 08/10/2023] Open
Abstract
With increasing resistance of SARS-CoV-2 variants to antibodies, there is interest in developing entry inhibitors that target essential receptor-binding regions of the viral Spike protein and thereby present a high bar for viral resistance. Such inhibitors could be derivatives of the viral receptor, ACE2, or peptides engineered to interact specifically with the Spike receptor-binding pocket. We compared the efficacy of a series of both types of entry inhibitors, constructed as fusions to an antibody Fc domain. Such a design can increase protein stability and act to both neutralize free virus and recruit effector functions to clear infected cells. We tested the reagents against prototype variants of SARS-CoV-2, using both Spike pseudotyped vesicular stomatitis virus vectors and replication-competent viruses. These analyses revealed that an optimized ACE2 derivative could neutralize all variants we tested with high efficacy. In contrast, the Spike-binding peptides had varying activities against different variants, with resistance observed in the Spike proteins from Beta, Gamma, and Omicron (BA.1 and BA.5). The resistance mapped to mutations at Spike residues K417 and N501 and could be overcome for one of the peptides by linking two copies in tandem, effectively creating a tetrameric reagent in the Fc fusion. Finally, both the optimized ACE2 and tetrameric peptide inhibitors provided some protection to human ACE2 transgenic mice challenged with the SARS-CoV-2 Delta variant, which typically causes death in this model within 7-9 days. IMPORTANCE The increasing resistance of SARS-CoV-2 variants to therapeutic antibodies has highlighted the need for new treatment options, especially in individuals who do not respond to vaccination. Receptor decoys that block viral entry are an attractive approach because of the presumed high bar to developing viral resistance. Here, we compare two entry inhibitors based on derivatives of the ACE2 receptor, or engineered peptides that bind to the receptor-binding pocket of the SARS-CoV-2 Spike protein. In each case, the inhibitors were fused to immunoglobulin Fc domains, which can further enhance therapeutic properties, and compared for activity against different SARS-CoV-2 variants. Potent inhibition against multiple SARS-CoV-2 variants was demonstrated in vitro, and even relatively low single doses of optimized reagents provided some protection in a mouse model, confirming their potential as an alternative to antibody therapies.
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Affiliation(s)
- George N. Llewellyn
- Department of Molecular Microbiology and Immunology, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
| | - Hsu-Yu Chen
- Department of Molecular Microbiology and Immunology, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
| | - Geoffrey L. Rogers
- Department of Molecular Microbiology and Immunology, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
| | - Xiaoli Huang
- Department of Molecular Microbiology and Immunology, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
| | - Philip J. Sell
- The Hastings Foundation and The Wright Foundation Laboratories, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
| | - Jill E. Henley
- The Hastings Foundation and The Wright Foundation Laboratories, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
| | - Paula M. Cannon
- Department of Molecular Microbiology and Immunology, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
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Luo H, Lv L, Yi J, Zhou Y, Liu C. Establishment of Replication Deficient Vesicular Stomatitis Virus for Studies of PEDV Spike-Mediated Cell Entry and Its Inhibition. Microorganisms 2023; 11:2075. [PMID: 37630636 PMCID: PMC10457912 DOI: 10.3390/microorganisms11082075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 08/08/2023] [Accepted: 08/09/2023] [Indexed: 08/27/2023] Open
Abstract
The porcine epidemic diarrhea virus (PEDV) is a highly contagious and virulent enteric coronavirus that causes severe enteric disease in pigs worldwide. PEDV infection causes profound diarrhea, vomiting, and dehydration in pigs of all ages, resulting in high mortality rates, particularly among neonatal piglets. The spike glycoprotein (S) of PEDV plays a crucial role in binding to the host cell receptor and facilitating fusion between the viral and host membranes. Pseudotyped viral particles featuring the PEDV S protein are valuable tools for investigating virus entry, identifying neutralizing antibodies, and developing small molecules to impede virus replication. In this study, we used a codon-optimized PEDV S protein to generate recombinant pseudotyped vesicular stomatitis virus (VSV) particles (rVSV-ΔG-EGFP-S). The full-length S protein was efficiently incorporated into VSV particles. The S protein pseudotyped VSV exhibited infectivity towards permissive cell lines of PEDV. Moreover, we identified a new permissive cell line, JHH7, which showed robust support for PEDV replication. In contrast to the SARS-CoV-2 spike protein, the removal of amino acids from the cytoplasmic tail resulted in reduced efficiency of viral pseudotyping. Furthermore, we demonstrated that 25-hydroxycholesterol inhibited rVSV-ΔG-EGFP-S entry, while human APN facilitated rVSV-ΔG-EGFP-S entry through the use of ANPEP knockout Huh7 cells. Finally, by transducing swine intestinal organoids with the rVSV-ΔG-EGFP-S virus, we observed efficient infection of the swine intestinal organoids by the PEDV spike-pseudotyped VSV. Our work offers valuable tools for studying the cellular entry of PEDV and developing interventions to curb its transmission.
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Affiliation(s)
- Huaye Luo
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China; (H.L.); (L.L.); (J.Y.); (Y.Z.)
| | - Lilei Lv
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China; (H.L.); (L.L.); (J.Y.); (Y.Z.)
| | - Jingxuan Yi
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China; (H.L.); (L.L.); (J.Y.); (Y.Z.)
| | - Yanjun Zhou
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China; (H.L.); (L.L.); (J.Y.); (Y.Z.)
- Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonosis, Yangzhou University, Yangzhou 225009, China
| | - Changlong Liu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China; (H.L.); (L.L.); (J.Y.); (Y.Z.)
- Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonosis, Yangzhou University, Yangzhou 225009, China
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8
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Li L, Sottas CM, Chen HY, Li Y, Cui H, Villano JS, Mankowski JL, Cannon PM, Papadopoulos V. SARS-CoV-2 Enters Human Leydig Cells and Affects Testosterone Production In Vitro. Cells 2023; 12:1198. [PMID: 37190107 PMCID: PMC10136776 DOI: 10.3390/cells12081198] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 04/11/2023] [Accepted: 04/16/2023] [Indexed: 05/17/2023] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a SARS-like coronavirus, continues to produce mounting infections and fatalities all over the world. Recent data point to SARS-CoV-2 viral infections in the human testis. As low testosterone levels are associated with SARS-CoV-2 viral infections in males and human Leydig cells are the main source of testosterone, we hypothesized that SARS-CoV-2 could infect human Leydig cells and impair their function. We successfully detected SARS-CoV-2 nucleocapsid in testicular Leydig cells of SARS-CoV-2-infected hamsters, providing evidence that Leydig cells can be infected with SARS-CoV-2. We then employed human Leydig-like cells (hLLCs) to show that the SARS-CoV-2 receptor angiotensin-converting enzyme 2 is highly expressed in hLLCs. Using a cell binding assay and a SARS-CoV-2 spike-pseudotyped viral vector (SARS-CoV-2 spike pseudovector), we showed that SARS-CoV-2 could enter hLLCs and increase testosterone production by hLLCs. We further combined the SARS-CoV-2 spike pseudovector system with pseudovector-based inhibition assays to show that SARS-CoV-2 enters hLLCs through pathways distinct from those of monkey kidney Vero E6 cells, a typical model used to study SARS-CoV-2 entry mechanisms. We finally revealed that neuropilin-1 and cathepsin B/L are expressed in hLLCs and human testes, raising the possibility that SARS-CoV-2 may enter hLLCs through these receptors or proteases. In conclusion, our study shows that SARS-CoV-2 can enter hLLCs through a distinct pathway and alter testosterone production.
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Affiliation(s)
- Lu Li
- Department of Pharmacology and Pharmaceutical Sciences, Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Chantal M. Sottas
- Department of Pharmacology and Pharmaceutical Sciences, Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Hsu-Yu Chen
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Yuchang Li
- Department of Pharmacology and Pharmaceutical Sciences, Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Haoyi Cui
- Department of Pharmacology and Pharmaceutical Sciences, Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Jason S. Villano
- Departments of Molecular and Comparative Pathobiology, Pathology and Neurology, The Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Joseph L. Mankowski
- Departments of Molecular and Comparative Pathobiology, Pathology and Neurology, The Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Paula M. Cannon
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Vassilios Papadopoulos
- Department of Pharmacology and Pharmaceutical Sciences, Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA
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9
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Cytoplasmic Tail Truncation Stabilizes S1-S2 Association and Enhances S Protein Incorporation into SARS-CoV-2 Pseudovirions. J Virol 2023; 97:e0165022. [PMID: 36790205 PMCID: PMC10062125 DOI: 10.1128/jvi.01650-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
Truncations of the cytoplasmic tail (CT) of entry proteins of enveloped viruses dramatically increase the infectivity of pseudoviruses (PVs) bearing these proteins. Several mechanisms have been proposed to explain this enhanced entry, including an increase in cell surface expression. However, alternative explanations have also been forwarded, and the underlying mechanisms for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) S protein remain undetermined. Here, we show that the partial or complete deletion of the CT (residues 19 to 35) does not modify SARS-CoV-2 S protein expression on the cell surface when the S2 subunit is measured, whereas it is significantly increased when the S1 subunit is measured. We also show that the higher level of S1 in these CT-truncated S proteins reflects the decreased dissociation of the S1 subunit from the S2 subunit. In addition, we demonstrate that CT truncation further promotes S protein incorporation into PV particles, as indicated by biochemical analyses and cryo-electron microscopy. Thus, our data show that two distinct mechanisms contribute to the markedly increased infectivity of PVs carrying CT-truncated SARS-CoV-2 S proteins and help clarify the interpretation of the results of studies employing such PVs. IMPORTANCE Various forms of PVs have been used as tools to evaluate vaccine efficacy and study virus entry steps. When PV infectivity is inherently low, such as that of SARS-CoV-2, a CT-truncated version of the viral entry glycoprotein is widely used to enhance PV infectivity, but the mechanism underlying this enhanced PV infectivity has been unclear. Here, our study identified two mechanisms by which the CT truncation of the SARS-CoV-2 S protein dramatically increases PV infectivity: a reduction of S1 shedding and an increase in S protein incorporation into PV particles. An understanding of these mechanisms can clarify the mechanistic bases for the differences observed among various assays employing such PVs.
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10
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Characterization of a Vesicular Stomatitis Virus-Vectored Recombinant Virus Bearing Spike Protein of SARS-CoV-2 Delta Variant. Microorganisms 2023; 11:microorganisms11020431. [PMID: 36838396 PMCID: PMC9960918 DOI: 10.3390/microorganisms11020431] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/29/2023] [Accepted: 02/01/2023] [Indexed: 02/11/2023] Open
Abstract
The frequent emergence of SARS-CoV-2 variants thwarts the prophylactic and therapeutic countermeasures confronting COVID-19. Among them, the Delta variant attracts widespread attention due to its high pathogenicity and fatality rate compared with other variants. However, with the emergence of new variants, studies on Delta variants have been gradually weakened and ignored. In this study, a replication-competent recombinant virus carrying the S protein of the SARS-CoV-2 Delta variant was established based on the vesicular stomatitis virus (VSV), which presented a safe alternative model for studying the Delta variant. The recombinant virus showed a replication advantage in Vero E6 cells, and the viral titers reach 107.3 TCID50/mL at 36 h post-inoculation. In the VSV-vectored recombinant platform, the spike proteins of the Delta variant mediated higher fusion activity and syncytium formation than the wild-type strain. Notably, the recombinant virus was avirulent in BALB/c mice, Syrian hamsters, 3-day ICR suckling mice, and IFNAR/GR-/- mice. It induced protective neutralizing antibodies in rodents, and protected the Syrian hamsters against the SARS-CoV-2 Delta variant infection. Meanwhile, the eGFP reporter of recombinant virus enabled the visual assay of neutralizing antibodies. Therefore, the recombinant virus could be a safe and convenient surrogate tool for authentic SARS-CoV-2. This efficient and reliable model has significant potential for research on viral-host interactions, epidemiological investigation of serum-neutralizing antibodies, and vaccine development.
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11
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Hu L, Tang Y, Mei L, Liang M, Huang J, Wang X, Wu L, Jiang J, Li L, Long F, Xiao J, Tan L, Lu S, Peng T. A new intracellular targeting motif in the cytoplasmic tail of the spike protein may act as a target to inhibit SARS-CoV-2 assembly. Antiviral Res 2023; 209:105509. [PMID: 36572190 PMCID: PMC9788845 DOI: 10.1016/j.antiviral.2022.105509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/19/2022] [Accepted: 12/21/2022] [Indexed: 12/25/2022]
Abstract
Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a threat to global public health, underscoring the urgent need for the development of preventive and therapeutic measures. The spike (S) protein of SARS-CoV-2, which mediates receptor binding and subsequent membrane fusion to promote viral entry, is a major target for current drug development and vaccine design. The S protein comprises a large N-terminal extracellular domain, a transmembrane domain, and a short cytoplasmic tail (CT) at the C-terminus. CT truncation of the S protein has been previously reported to promote the infectivity of SARS-CoV and SARS-CoV-2 pseudoviruses. However, the underlying molecular mechanism has not been precisely elucidated. In addition, the CT of various viral membrane glycoproteins play an essential role in the assembly of virions, yet the role of the S protein CT in SARS-CoV-2 infection remains unclear. In this study, through constructing a series of mutations of the CT of the S protein and analyzing their impact on the packaging of the SARS-CoV-2 pseudovirus and live SARS-CoV-2 virus, we identified V1264L1265 as a new intracellular targeting motif in the CT of the S protein, that regulates the transport and subcellular localization of the spike protein through the interactions with cytoskeleton and vesicular transport-related proteins, ARPC3, SCAMP3, and TUBB8, thereby modulating SARS-CoV-2 pseudovirus and live SARS-CoV-2 virion assembly. Either disrupting the V1264L1265 motif or reducing the expression of ARPC3, SCAMP3, and TUBB8 significantly repressed the assembly of the live SARS-CoV-2 virion, raising the possibility that the V1264L1265 motif and the host responsive pathways involved could be new drug targets for the treatment of SARS-CoV-2 infection. Our results extend the understanding of the role played by the S protein CT in the assembly of pseudoviruses and live SARS-CoV-2 virions, which will facilitate the application of pseudoviruses to the study of SARS-CoV-2 and provide potential strategies for the treatment of SARS-CoV-2 infection.
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Affiliation(s)
- Longbo Hu
- State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China,Corresponding author
| | - Yongjie Tang
- State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China
| | - Lingling Mei
- State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China
| | - Mengdi Liang
- State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China
| | - Jinxian Huang
- State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China
| | - Xufei Wang
- State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China
| | - Liping Wu
- State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China
| | - Jiajing Jiang
- State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China
| | - Leyi Li
- State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China
| | - Fei Long
- State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China
| | - Jing Xiao
- State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China
| | - Long Tan
- State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China
| | - Shaohua Lu
- State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China
| | - Tao Peng
- State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China,Guangdong South China Vaccine, Guangzhou, China,Greater Bay Area Innovative Vaccine Technology Development Center, Guangzhou International Bio-island Laboratory, China,Corresponding author. State Key Laboratory of Respiratory Disease, Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou, 511436, China
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12
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Lista MJ, Winstone H, Wilson HD, Dyer A, Pickering S, Galao RP, De Lorenzo G, Cowton VM, Furnon W, Suarez N, Orton R, Palmarini M, Patel AH, Snell L, Nebbia G, Swanson C, Neil SJD. The P681H Mutation in the Spike Glycoprotein of the Alpha Variant of SARS-CoV-2 Escapes IFITM Restriction and Is Necessary for Type I Interferon Resistance. J Virol 2022; 96:e0125022. [PMID: 36350154 PMCID: PMC9749455 DOI: 10.1128/jvi.01250-22] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 10/10/2022] [Indexed: 11/11/2022] Open
Abstract
The appearance of new dominant variants of concern (VOC) of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) threatens the global response to the coronavirus disease 2019 (COVID-19) pandemic. Of these, the alpha variant (also known as B.1.1.7), which appeared initially in the United Kingdom, became the dominant variant in much of Europe and North America in the first half of 2021. The spike (S) glycoprotein of alpha acquired seven mutations and two deletions compared to the ancestral virus, including the P681H mutation adjacent to the polybasic cleavage site, which has been suggested to enhance S cleavage. Here, we show that the alpha spike protein confers a level of resistance to beta interferon (IFN-β) in human lung epithelial cells. This correlates with resistance to an entry restriction mediated by interferon-induced transmembrane protein 2 (IFITM2) and a pronounced infection enhancement by IFITM3. Furthermore, the P681H mutation is essential for resistance to IFN-β and context-dependent resistance to IFITMs in the alpha S. P681H reduces dependence on endosomal cathepsins, consistent with enhanced cell surface entry. However, reversion of H681 does not reduce cleaved spike incorporation into particles, indicating that it exerts its effect on entry and IFN-β downstream of furin cleavage. Overall, we suggest that, in addition to adaptive immune escape, mutations associated with VOC may well also confer a replication and/or transmission advantage through adaptation to resist innate immune mechanisms. IMPORTANCE Accumulating evidence suggests that variants of concern (VOC) of SARS-CoV-2 evolve to evade the human immune response, with much interest focused on mutations in the spike protein that escape from antibodies. However, resistance to the innate immune response is essential for efficient viral replication and transmission. Here, we show that the alpha (B.1.1.7) VOC of SARS-CoV-2 is substantially more resistant to type I interferons than the parental Wuhan-like virus. This correlates with resistance to the antiviral protein IFITM2 and enhancement by its paralogue IFITM3. The key determinant of this is a proline-to-histidine change at position 681 in S adjacent to the furin cleavage site, which in the context of the alpha spike modulates cell entry pathways of SARS-CoV-2. Reversion of the mutation is sufficient to restore interferon and IFITM2 sensitivity, highlighting the dynamic nature of the SARS CoV-2 as it adapts to both innate and adaptive immunity in the humans.
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Affiliation(s)
- Maria Jose Lista
- Department of Infectious Diseases, King’s College London, London, United Kingdom
- UKRI Genotype-2-Phenotype Consortium, London, United Kingdom
| | - Helena Winstone
- Department of Infectious Diseases, King’s College London, London, United Kingdom
- UKRI Genotype-2-Phenotype Consortium, London, United Kingdom
| | - Harry D. Wilson
- Department of Infectious Diseases, King’s College London, London, United Kingdom
- UKRI Genotype-2-Phenotype Consortium, London, United Kingdom
| | - Adam Dyer
- Department of Infectious Diseases, King’s College London, London, United Kingdom
- UKRI Genotype-2-Phenotype Consortium, London, United Kingdom
| | - Suzanne Pickering
- Department of Infectious Diseases, King’s College London, London, United Kingdom
- UKRI Genotype-2-Phenotype Consortium, London, United Kingdom
| | - Rui Pedro Galao
- Department of Infectious Diseases, King’s College London, London, United Kingdom
- UKRI Genotype-2-Phenotype Consortium, London, United Kingdom
| | - Giuditta De Lorenzo
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - Vanessa M. Cowton
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - Wilhelm Furnon
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - Nicolas Suarez
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - Richard Orton
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - Massimo Palmarini
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
- UKRI Genotype-2-Phenotype Consortium, London, United Kingdom
| | - Arvind H. Patel
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
- UKRI Genotype-2-Phenotype Consortium, London, United Kingdom
| | - Luke Snell
- Centre for Clinical Infection and Diagnostics Research, Department of Infectious Diseases, Guy’s and St Thomas’ NHS Foundation Trust, London, United Kingdom
| | - Gaia Nebbia
- Centre for Clinical Infection and Diagnostics Research, Department of Infectious Diseases, Guy’s and St Thomas’ NHS Foundation Trust, London, United Kingdom
| | - Chad Swanson
- Department of Infectious Diseases, King’s College London, London, United Kingdom
| | - Stuart J. D. Neil
- Department of Infectious Diseases, King’s College London, London, United Kingdom
- UKRI Genotype-2-Phenotype Consortium, London, United Kingdom
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Hydroxypropyl-beta-cyclodextrin (HP-BCD) inhibits SARS-CoV-2 replication and virus-induced inflammatory cytokines. Antiviral Res 2022; 205:105373. [PMID: 35798224 PMCID: PMC9250893 DOI: 10.1016/j.antiviral.2022.105373] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 06/24/2022] [Accepted: 06/28/2022] [Indexed: 11/22/2022]
Abstract
COVID-19 is marked by extensive damage to the respiratory system, often accompanied by systemic manifestations, due to both viral cytopathic effects and hyperinflammatory syndrome. Therefore, the development of new therapeutic strategies or drug repurposing aiming to control virus replication and inflammation are required to mitigate the impact of the disease. Hydroxypropyl-beta-cyclodextrin (HP-BCD) is a cholesterol-sequestering agent with antiviral activity that has been demonstrated against enveloped viruses in in vitro and in vivo experimental models. We also demonstrated that HP-BCD has an immunomodulatory effect, inhibiting the production of selected proinflammatory cytokines induced by microbial products. Importantly, this drug has been used in humans for decades as an excipient in drug delivery systems and as a therapeutic agent in the treatment of Niemann pick C disease. The safety profile for this compound is well established. Here, we investigated whether HP-BCD would affect SARS-CoV-2 replication and virus-induced inflammatory response, using established cell lines and primary human cells. Treating virus or cells with HP-BCD significantly inhibited SARS-CoV-2 replication with a high selective index. A broad activity against distinct SARS-CoV-2 variants was evidenced by a remarkable reduction in the release of infectious particles. The drug did not alter ACE2 surface expression, but affected cholesterol accumulation into intracellular replication complexes, lowering virus RNA and protein levels, and reducing virus-induced cytopathic effects. Virus replication was also impaired by HP-BCD in Calu-3 pulmonary cell line and human primary monocytes, in which not only the virus, but also the production of proinflammatory cytokines were significantly inhibited. Given the pathophysiology of COVID-19 disease, these data indicate that the use HP-BCD, which inhibits both SARS-CoV2 replication and production of proinflammatory cytokines, as a potential COVID-19 therapeutic warrants further investigation.
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Unique Aggregation of Retroviral Particles Pseudotyped with the Delta Variant SARS-CoV-2 Spike Protein. Viruses 2022; 14:v14051024. [PMID: 35632764 PMCID: PMC9147488 DOI: 10.3390/v14051024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 05/02/2022] [Accepted: 05/05/2022] [Indexed: 02/04/2023] Open
Abstract
Individuals infected with the SARS-CoV-2 Delta variant, lineage B.1.617.2, exhibit faster initial infection with a higher viral load than prior variants, and pseudotyped viral particles bearing the SARS-CoV-2 Delta variant spike protein induce a faster initial infection rate of target cells compared to those bearing other SARS-CoV-2 variant spikes. Here, we show that pseudotyped viral particles bearing the Delta variant spike form unique aggregates, as evidenced by negative stain and cryogenic electron microscopy (EM), flow cytometry, and nanoparticle tracking analysis. Viral particles pseudotyped with other SARS-CoV-2 spike variants do not show aggregation by any of these criteria. The contribution to infection kinetics of the Delta spike’s unique property to aggregate is discussed with respect to recent evidence for collective infection by other viruses. Irrespective of this intriguing possibility, spike-dependent aggregation is a new functional parameter of spike-expressing viral particles to evaluate in future spike protein variants.
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15
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Van Ert HA, Bohan DW, Rogers K, Fili M, Rojas Chávez RA, Qing E, Han C, Dempewolf S, Hu G, Schwery N, Sevcik K, Ruggio N, Boyt D, Pentella MA, Gallagher T, Jackson JB, Merrill AE, Knudson CM, Brown GD, Maury W, Haim H. Limited Variation between SARS-CoV-2-Infected Individuals in Domain Specificity and Relative Potency of the Antibody Response against the Spike Glycoprotein. Microbiol Spectr 2022; 10:e0267621. [PMID: 35080430 PMCID: PMC8791189 DOI: 10.1128/spectrum.02676-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 12/28/2021] [Indexed: 11/25/2022] Open
Abstract
The spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is arranged as a trimer on the virus surface, composed of three S1 and three S2 subunits. Infected and vaccinated individuals generate antibodies against spike, which can neutralize the virus. Most antibodies target the receptor-binding domain (RBD) and N-terminal domain (NTD) of S1; however, antibodies against other regions of spike have also been isolated. The interhost variability in domain specificity and relative neutralization efficacy of the antibodies is still poorly characterized. To this end, we tested serum and plasma samples collected from 85 coronavirus disease 2019 (COVID-19) convalescent subjects. Samples were analyzed using seven immunoassays that employ different domains, subunits, and oligomeric forms of spike to capture the antibodies. Samples were also tested for their neutralization of pseudovirus containing SARS-CoV-2 spike and of replication-competent SARS-CoV-2. While the total amount of anti-spike antibodies produced varied among convalescent subjects, we observed an unexpectedly fixed ratio of RBD- to NTD-targeting antibodies. The relative potency of the response (defined as the measured neutralization efficacy relative to the total level of spike-targeting antibodies) also exhibited limited variation between subjects and was not associated with the overall amount of antispike antibodies produced. These studies suggest that host-to-host variation in the polyclonal response elicited against SARS-CoV-2 spike in early pandemic subjects is primarily limited to the quantity of antibodies generated rather than their domain specificity or relative neutralization potency. IMPORTANCE Infection by SARS-CoV-2 elicits antibodies against various domains of the spike protein, including the RBD and NTD of subunit S1 and against subunit S2. The antibody responses of different infected individuals exhibit different efficacies to inactivate (neutralize) the virus. Here, we show that the observed variation in the neutralizing activity of the antibody responses in COVID-19 convalescent subjects is caused by differences in the amounts of antibodies rather than their recognition properties or the potency of their antiviral activity. These findings suggest that COVID-19 vaccine strategies that focus on enhancing the overall level of the antibodies will likely elicit a more uniformly efficacious protective response.
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Affiliation(s)
- Hanora A. Van Ert
- Department of Microbiology and Immunology, The University of Iowa, Iowa City, Iowa, United States
| | - Dana W. Bohan
- Department of Microbiology and Immunology, The University of Iowa, Iowa City, Iowa, United States
| | - Kai Rogers
- Department of Microbiology and Immunology, The University of Iowa, Iowa City, Iowa, United States
| | - Mohammad Fili
- Department of Industrial and Manufacturing Systems Engineering, Iowa State University, Ames, Iowa, United States
| | - Roberth A. Rojas Chávez
- Department of Microbiology and Immunology, The University of Iowa, Iowa City, Iowa, United States
| | - Enya Qing
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, United States
| | - Changze Han
- Department of Microbiology and Immunology, The University of Iowa, Iowa City, Iowa, United States
| | - Spencer Dempewolf
- Department of Microbiology and Immunology, The University of Iowa, Iowa City, Iowa, United States
| | - Guiping Hu
- Department of Industrial and Manufacturing Systems Engineering, Iowa State University, Ames, Iowa, United States
| | - Nathan Schwery
- Department of Microbiology and Immunology, The University of Iowa, Iowa City, Iowa, United States
| | - Kristina Sevcik
- Department of Microbiology and Immunology, The University of Iowa, Iowa City, Iowa, United States
| | - Natalie Ruggio
- Department of Microbiology and Immunology, The University of Iowa, Iowa City, Iowa, United States
| | - Devlin Boyt
- Department of Microbiology and Immunology, The University of Iowa, Iowa City, Iowa, United States
| | - Michael A. Pentella
- State Hygienic Laboratory, The University of Iowa, Iowa City, Iowa, United States
| | - Tom Gallagher
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, United States
| | - J. Brooks Jackson
- Department of Pathology, University of Iowa Hospitals & Clinics, Iowa City, Iowa, United States
| | - Anna E. Merrill
- Department of Pathology, University of Iowa Hospitals & Clinics, Iowa City, Iowa, United States
| | - C. Michael Knudson
- Department of Pathology, University of Iowa Hospitals & Clinics, Iowa City, Iowa, United States
| | - Grant D. Brown
- Department of Biostatistics, School of Public Health, The University of Iowa, Iowa City, Iowa, United States
| | - Wendy Maury
- Department of Microbiology and Immunology, The University of Iowa, Iowa City, Iowa, United States
| | - Hillel Haim
- Department of Microbiology and Immunology, The University of Iowa, Iowa City, Iowa, United States
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