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Adair A, Tan LL, Feng J, Girkin J, Bryant N, Wang M, Mordant F, Chan LJ, Bartlett NW, Subbarao K, Pymm P, Tham WH. Human coronavirus OC43 nanobody neutralizes virus and protects mice from infection. J Virol 2024; 98:e0053124. [PMID: 38709106 PMCID: PMC11237593 DOI: 10.1128/jvi.00531-24] [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: 03/27/2024] [Accepted: 03/29/2024] [Indexed: 05/07/2024] Open
Abstract
Human coronavirus (hCoV) OC43 is endemic to global populations and usually causes asymptomatic or mild upper respiratory tract illness. Here, we demonstrate the neutralization efficacy of isolated nanobodies from alpacas immunized with the S1B and S1C domain of the hCoV-OC43 spike glycoprotein. A total of 40 nanobodies bound to recombinant OC43 protein with affinities ranging from 1 to 149 nM. Two nanobodies WNb 293 and WNb 294 neutralized virus at 0.21 and 1.79 nM, respectively. Intranasal and intraperitoneal delivery of WNb 293 fused to an Fc domain significantly reduced nasal viral load in a mouse model of hCoV-OC43 infection. Using X-ray crystallography, we observed that WNb 293 bound to an epitope on the OC43 S1B domain, distal from the sialoglycan-binding site involved in host cell entry. This result suggests that neutralization mechanism of this nanobody does not involve disruption of glycan binding. Our work provides characterization of nanobodies against hCoV-OC43 that blocks virus entry and reduces viral loads in vivo and may contribute to future nanobody-based therapies for hCoV-OC43 infections. IMPORTANCE The pandemic potential presented by coronaviruses has been demonstrated by the ongoing COVID-19 pandemic and previous epidemics caused by severe acute respiratory syndrome coronavirus and Middle East respiratory syndrome coronavirus. Outside of these major pathogenic coronaviruses, there are four endemic coronaviruses that infect humans: hCoV-OC43, hCoV-229E, hCoV-HKU1, and hCoV-NL63. We identified a collection of nanobodies against human coronavirus OC43 (hCoV-OC43) and found that two high-affinity nanobodies potently neutralized hCoV-OC43 at low nanomolar concentrations. Prophylactic administration of one neutralizing nanobody reduced viral loads in mice infected with hCoV-OC43, showing the potential for nanobody-based therapies for hCoV-OC43 infections.
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Affiliation(s)
- Amy Adair
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Li Lynn Tan
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Jackson Feng
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Jason Girkin
- />College of Health, Medicine and Wellbeing, University of Newcastle, Callaghan, New South Wales, Australia
- Infection Research Program, Hunter Medical Research Institute, New Lambton Heights, New South Wales, Australia
| | - Nathan Bryant
- />College of Health, Medicine and Wellbeing, University of Newcastle, Callaghan, New South Wales, Australia
- Infection Research Program, Hunter Medical Research Institute, New Lambton Heights, New South Wales, Australia
| | - Mingyang Wang
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Francesca Mordant
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Li-Jin Chan
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Nathan W. Bartlett
- />College of Health, Medicine and Wellbeing, University of Newcastle, Callaghan, New South Wales, Australia
- Infection Research Program, Hunter Medical Research Institute, New Lambton Heights, New South Wales, Australia
| | - Kanta Subbarao
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
- WHO Collaborating Centre for Reference and Research on Influenza, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Phillip Pymm
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Wai-Hong Tham
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, Victoria, Australia
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Nanobodies against Pfs230 block Plasmodium falciparum transmission. Biochem J 2022; 479:2529-2546. [PMID: 36520108 PMCID: PMC9788556 DOI: 10.1042/bcj20220554] [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: 11/15/2022] [Revised: 12/13/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022]
Abstract
Transmission blocking interventions can stop malaria parasite transmission from mosquito to human by inhibiting parasite infection in mosquitos. One of the most advanced candidates for a malaria transmission blocking vaccine is Pfs230. Pfs230 is the largest member of the 6-cysteine protein family with 14 consecutive 6-cysteine domains and is expressed on the surface of gametocytes and gametes. Here, we present the crystal structure of the first two 6-cysteine domains of Pfs230. We identified high affinity Pfs230-specific nanobodies that recognized gametocytes and bind to distinct sites on Pfs230, which were isolated from immunized alpacas. Using two non-overlapping Pfs230 nanobodies, we show that these nanobodies significantly blocked P. falciparum transmission and reduced the formation of exflagellation centers. Crystal structures of the transmission blocking nanobodies with the first 6-cysteine domain of Pfs230 confirm that they bind to different epitopes. In addition, these nanobodies bind to Pfs230 in the absence of the prodomain, in contrast with the binding of known Pfs230 transmission blocking antibodies. These results provide additional structural insight into Pfs230 domains and elucidate a mechanism of action of transmission blocking Pfs230 nanobodies.
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Lyons FMT, Gabriela M, Tham WH, Dietrich MH. Plasmodium 6-Cysteine Proteins: Functional Diversity, Transmission-Blocking Antibodies and Structural Scaffolds. Front Cell Infect Microbiol 2022; 12:945924. [PMID: 35899047 PMCID: PMC9309271 DOI: 10.3389/fcimb.2022.945924] [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: 05/17/2022] [Accepted: 06/22/2022] [Indexed: 11/30/2022] Open
Abstract
The 6-cysteine protein family is one of the most abundant surface antigens that are expressed throughout the Plasmodium falciparum life cycle. Many members of the 6-cysteine family have critical roles in parasite development across the life cycle in parasite transmission, evasion of the host immune response and host cell invasion. The common feature of the family is the 6-cysteine domain, also referred to as s48/45 domain, which is conserved across Aconoidasida. This review summarizes the current approaches for recombinant expression for 6-cysteine proteins, monoclonal antibodies against 6-cysteine proteins that block transmission and the growing collection of crystal structures that provide insights into the functional domains of this protein family.
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Affiliation(s)
- Frankie M. T. Lyons
- The Walter and Eliza Hall Institute of Medical Research, Infectious Diseases and Immune Defence Division, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
| | - Mikha Gabriela
- The Walter and Eliza Hall Institute of Medical Research, Infectious Diseases and Immune Defence Division, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
| | - Wai-Hong Tham
- The Walter and Eliza Hall Institute of Medical Research, Infectious Diseases and Immune Defence Division, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
| | - Melanie H. Dietrich
- The Walter and Eliza Hall Institute of Medical Research, Infectious Diseases and Immune Defence Division, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
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PCRCR complex is essential for invasion of human erythrocytes by Plasmodium falciparum. Nat Microbiol 2022; 7:2039-2053. [PMID: 36396942 PMCID: PMC9712106 DOI: 10.1038/s41564-022-01261-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 10/03/2022] [Indexed: 11/18/2022]
Abstract
The most severe form of malaria is caused by Plasmodium falciparum. These parasites invade human erythrocytes, and an essential step in this process involves the ligand PfRh5, which forms a complex with cysteine-rich protective antigen (CyRPA) and PfRh5-interacting protein (PfRipr) (RCR complex) and binds basigin on the host cell. We identified a heteromeric disulfide-linked complex consisting of P. falciparum Plasmodium thrombospondin-related apical merozoite protein (PfPTRAMP) and P. falciparum cysteine-rich small secreted protein (PfCSS) and have shown that it binds RCR to form a pentameric complex, PCRCR. Using P. falciparum lines with conditional knockouts, invasion inhibitory nanobodies to both PfPTRAMP and PfCSS, and lattice light-sheet microscopy, we show that they are essential for merozoite invasion. The PCRCR complex functions to anchor the contact between merozoite and erythrocyte membranes brought together by strong parasite deformations. We solved the structure of nanobody-PfCSS complexes to identify an inhibitory epitope. Our results define the function of the PCRCR complex and identify invasion neutralizing epitopes providing a roadmap for structure-guided development of these proteins for a blood stage malaria vaccine.
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