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Lanning S, Aguilar-Hernández N, Serrão VHB, López T, O'Rourke SM, Lentz A, Ricemeyer L, Espinosa R, López S, Arias CF, DuBois RM. Discovery of three novel neutralizing antibody epitopes on the human astrovirus capsid spike and mechanistic insights into virus neutralization. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.14.613010. [PMID: 39314284 PMCID: PMC11419155 DOI: 10.1101/2024.09.14.613010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 09/25/2024]
Abstract
Human astroviruses (HAstVs) are a leading cause of viral childhood diarrhea that infect nearly every individual during their lifetime. Although human astroviruses are highly prevalent, no approved vaccine currently exists. Antibody responses appear to play an important role in protection from HAstV infection, however knowledge about the neutralizing epitope landscape is lacking, as only 3 neutralizing antibody epitopes have previously been determined. Here, we structurally define the epitopes of 3 uncharacterized HAstV-neutralizing monoclonal antibodies: antibody 4B6 with X-ray crystallography to 2.67 Å, and antibodies 3H4 and 3B4 simultaneously with single-particle cryogenic-electron microscopy to 3.33 Å. We assess the epitope locations relative to conserved regions on the capsid spike and find that while antibodies 4B6 and 3B4 target the upper variable loop regions of the HAstV spike protein, antibody 3H4 targets a novel region near the base of the spike that is more conserved. Additionally, we found that all 3 antibodies bind with high affinity, and they compete with receptor FcRn binding to the capsid spike. These studies inform which regions of the HAstV capsid can be targeted by monoclonal antibody therapies and could aid in rational vaccine design.
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Affiliation(s)
- Sarah Lanning
- Department of Molecular Cell and Developmental Biology, University of California Santa Cruz
- Department of Biomolecular Engineering, University of California Santa Cruz
| | - Nayeli Aguilar-Hernández
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México
| | - Vitor Hugo B Serrão
- Biomolecular Cryo-electron Microscopy Facility, University of California Santa Cruz
- Department of Chemistry and Biochemistry, University of California Santa Cruz
| | - Tomás López
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México
| | - Sara M O'Rourke
- Department of Biomolecular Engineering, University of California Santa Cruz
| | - Adam Lentz
- Department of Biomolecular Engineering, University of California Santa Cruz
| | - Lena Ricemeyer
- Department of Biomolecular Engineering, University of California Santa Cruz
| | - Rafaela Espinosa
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México
| | - Susana López
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México
| | - Carlos F Arias
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México
| | - Rebecca M DuBois
- Department of Biomolecular Engineering, University of California Santa Cruz
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Ghosh A, Delgado-Cunningham K, López T, Green K, Arias CF, DuBois RM. Structure and antigenicity of the divergent human astrovirus VA1 capsid spike. PLoS Pathog 2024; 20:e1012028. [PMID: 38416796 PMCID: PMC10950212 DOI: 10.1371/journal.ppat.1012028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 03/19/2024] [Accepted: 02/05/2024] [Indexed: 03/01/2024] Open
Abstract
Human astrovirus (HAstV) is a known cause of viral gastroenteritis in children worldwide, but HAstV can cause also severe and systemic infections in immunocompromised patients. There are three clades of HAstV: classical, MLB, and VA/HMO. While all three clades are found in gastrointestinal samples, HAstV-VA/HMO is the main clade associated with meningitis and encephalitis in immunocompromised patients. To understand how the HAstV-VA/HMO can infect the central nervous system, we investigated its sequence-divergent capsid spike, which functions in cell attachment and may influence viral tropism. Here we report the high-resolution crystal structures of the HAstV-VA1 capsid spike from strains isolated from patients with gastrointestinal and neuronal disease. The HAstV-VA1 spike forms a dimer and shares a core beta-barrel structure with other astrovirus capsid spikes but is otherwise strikingly different, suggesting that HAstV-VA1 may utilize a different cell receptor, and an infection competition assay supports this hypothesis. Furthermore, by mapping the capsid protease cleavage site onto the structure, the maturation and assembly of the HAstV-VA1 capsid is revealed. Finally, comparison of gastrointestinal and neuronal HAstV-VA1 sequences, structures, and antigenicity suggests that neuronal HAstV-VA1 strains may have acquired immune escape mutations. Overall, our studies on the HAstV-VA1 capsid spike lay a foundation to further investigate the biology of HAstV-VA/HMO and to develop vaccines and therapeutics targeting it.
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Affiliation(s)
- Anisa Ghosh
- Department of Biomolecular Engineering, University of California Santa Cruz, Santa Cruz, California, United States of America
| | - Kevin Delgado-Cunningham
- Department of Biomolecular Engineering, University of California Santa Cruz, Santa Cruz, California, United States of America
| | - Tomás López
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
| | - Kassidy Green
- Department of Biomolecular Engineering, University of California Santa Cruz, Santa Cruz, California, United States of America
| | - Carlos F. Arias
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
| | - Rebecca M. DuBois
- Department of Biomolecular Engineering, University of California Santa Cruz, Santa Cruz, California, United States of America
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Porto PS, Rivera A, Moonrinta R, Wobus CE. Entry and egress of human astroviruses. Adv Virus Res 2023; 117:81-119. [PMID: 37832992 DOI: 10.1016/bs.aivir.2023.08.001] [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] [Indexed: 10/15/2023]
Abstract
Astroviruses encapsidate a positive-sense, single-stranded RNA genome into ∼30nm icosahedral particles that infect a wide range of mammalian and avian species, but their biology is not well understood. Human astroviruses (HAstV) are divided into three clades: classical HAstV serotypes 1-8, and novel or non-classical HAstV of the MLB and VA clades. These viruses are part of two genogroups and phylogenetically cluster with other mammalian astroviruses, highlighting their zoonotic potential. HAstV are a highly prevalent cause of nonbacterial gastroenteritis, primarily in children, the elderly and immunocompromised. Additionally, asymptomatic infections and extraintestinal disease (e.g., encephalitis), are also observed, mostly in immunocompetent or immunocompromised individuals, respectively. While these viruses are highly prevalent, no approved vaccines or antivirals are available to prevent or treat infections. This is in large part due to their understudied nature and the limited understanding of even very basic features of their life cycle and pathogenesis at the cellular and organismal level. This review will summarize molecular features of human astrovirus biology, pathogenesis, and tropism, and then focus on two stages of the viral life cycle, namely entry and egress, since these are proven targets for therapeutic interventions. We will further highlight gaps in knowledge in hopes of stimulating future research into these understudied viruses.
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Affiliation(s)
- Pedro Soares Porto
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, United states
| | - Andres Rivera
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, United states
| | - Rootjikarn Moonrinta
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, United states
| | - Christiane E Wobus
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, United states.
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4
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Ykema M, Ye K, Xun M, Harper J, Betancourt-Solis MA, Arias CF, McNew JA, Tao YJ. Human astrovirus capsid protein releases a membrane lytic peptide upon trypsin maturation. J Virol 2023; 97:e0080223. [PMID: 37504573 PMCID: PMC10506485 DOI: 10.1128/jvi.00802-23] [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: 05/26/2023] [Accepted: 06/13/2023] [Indexed: 07/29/2023] Open
Abstract
The human astrovirus (HAstV) is a non-enveloped, single-stranded RNA virus that is a common cause of gastroenteritis. Most non-enveloped viruses use membrane disruption to deliver the viral genome into a host cell after virus uptake. The virus-host factors that allow for HAstV cell entry are currently unknown but thought to be associated with the host-protease-mediated viral maturation. Using in vitro liposome disruption analysis, we identified a trypsin-dependent lipid disruption activity in the capsid protein of HAstV serotype 8. This function was further localized to the P1 domain of the viral capsid core, which was both necessary and sufficient for membrane disruption. Site-directed mutagenesis identified a cluster of four trypsin cleavage sites necessary to retain the lipid disruption activity, which is likely attributed to a short stretch of sequence ending at arginine 313 based on mass spectrometry of liposome-associated peptides. The membrane disruption activity was conserved across several other HAstVs, including the emerging VA2 strain, and effective against a wide range of lipid identities. This work provides key functional insight into the protease maturation process essential to HAstV infectivity and presents a method to investigate membrane penetration by non-enveloped viruses in vitro. IMPORTANCE Human astroviruses (HAstVs) are an understudied family of viruses that cause mild gastroenteritis but have recent cases associated with a more severe neural pathogenesis. Many important elements of the HAstV life cycle are not well understood, and further elucidating them can help understand the various forms of HAstV pathogenesis. In this study, we utilized an in vitro liposome-based assay to describe and characterize a previously unreported lipid disruption activity. This activity is dependent on the protease cleavage of key sites in HAstV capsid core and can be controlled by site-directed mutagenesis. Our group observed this activity in multiple strains of HAstV and in multiple lipid conditions, indicating this may be a conserved activity across the AstV family. The discovery of this function provides insight into HAstV cellular entry, pathogenesis, and a possible target for future therapeutics.
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Affiliation(s)
- Matthew Ykema
- Department of BioSciences, Rice University, Houston, Texas, USA
| | - Kai Ye
- Department of BioSciences, Rice University, Houston, Texas, USA
| | - Meng Xun
- Department of BioSciences, Rice University, Houston, Texas, USA
| | - Justin Harper
- Department of BioSciences, Rice University, Houston, Texas, USA
| | | | - Carlos F. Arias
- Departamento de Genética del Desarrollo y Fisiología Molecular, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
| | - James A. McNew
- Department of BioSciences, Rice University, Houston, Texas, USA
| | - Yizhi Jane Tao
- Department of BioSciences, Rice University, Houston, Texas, USA
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A Review of Emerging Goose Astrovirus Causing Gout. BIOMED RESEARCH INTERNATIONAL 2022; 2022:1635373. [PMID: 36072471 PMCID: PMC9441354 DOI: 10.1155/2022/1635373] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 08/11/2022] [Indexed: 11/21/2022]
Abstract
In recent years, an infection in geese caused by goose astrovirus (GAstV) has repeatedly occurred in coastal areas of China and rapidly spread to inland provinces. The infection is characterized by joint and visceral gout and is fatal. The disease has caused huge economic losses to China's goose industry. GAstV is a nonenveloped, single-stranded, positive-sense RNA virus. As it is a novel virus, there is no specific classification. Here, we review the current understanding of GAstV. The virus structure, isolation, diagnosis and detection, innate immune regulation, and transmission route are discussed. In addition, since GAstV can cause gout in goslings, the possible role of GAstV in gout formation and uric acid metabolism is discussed. We hope that this review will inform researchers to rapidly develop effective methods to prevent and treat this disease.
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The Association of Human Astrovirus with Extracellular Vesicles Facilitates Cell Infection and Protects the Virus from Neutralizing Antibodies. J Virol 2022; 96:e0084822. [PMID: 35762754 PMCID: PMC9327681 DOI: 10.1128/jvi.00848-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Viral gastroenteritis has a global distribution and represents a high risk for vulnerable population and children under 5 years due to acute diarrhea, fever and dehydration. Human astroviruses (HAstV) have been identified as the third most important cause of viral gastroenteritis in pediatric and immunocompromised patients. Furthermore, HAstV has been reported in biopsies taken from patients with encephalitis, meningitis and acute respiratory infection, yet it is not clear how the virus reaches these organs. In this work we have tested the possibility that the released astrovirus particles could be associated with extracellular vesicles. Comparison between vesicles purified from HAstV Yuc8 infected and mock-infected cells showed that infection enhances production of vesicles larger than 150 nm. These vesicles contain CD63 and Alix, two markers of vesicular structures. Almost 70% of the extracellular virus present in clarified supernatant at 18 h postinfection was found associated with vesicular membranes, and this association facilitates cell infection in the absence of trypsin activation and protects virions from neutralizing antibodies. Our findings suggest a new pathway for HAstV spread and might represent an explanation for the extra-intestinal presence of some astrovirus strains. IMPORTANCE Astroviruses are an important cause of diarrhea in vulnerable population, particularly children; recently some reports have found these viruses in extra-intestinal organs, including the central nervous system, causing unexpected clinical disease. In this work, we found that human astrovirus strain Yuc8 associates with extracellular vesicles, possibly during or after their cell egress. The association with vesicles doubled astrovirus infectivity in less susceptible cells and rendered virus particles insensitive to neutralization by antibodies. These data suggest that extracellular vesicles could represent a novel pathway for astrovirus to disseminate outside the gastrointestinal tract.
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The Capsid Precursor Protein of Astrovirus VA1 Is Proteolytically Processed Intracellularly. J Virol 2022; 96:e0066522. [PMID: 35762760 PMCID: PMC9327696 DOI: 10.1128/jvi.00665-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Human astrovirus VA1 has been associated with neurological disease in immunocompromised patients, and its recent propagation in cell culture has opened the possibility to study its biology. Unlike classical human astroviruses, VA1 growth was found to be independent of trypsin during virus replication in vitro. In this work, we show that despite its independence on trypsin activation for cell infection, the VA1 capsid precursor protein, of 86 kDa (VP86), is processed intracellularly, and this proteolytic processing is important for astrovirus VA1 infectivity. Antibodies raised against different regions of the capsid precursor showed that the polyprotein can be processed starting at either its amino- or carboxy-terminal end, and they allowed us to identify those proteins of about 33 (VP33) and 38 (VP38) kDa constitute the core and the spike proteins of the mature infectious virus particles, respectively. The amino-terminal end of the spike protein was found to be Thr-348. Whether the protease involved in intracellular cleavage of the capsid precursor is of viral or cellular origin remains to be determined, but the cleavage is independent of caspases. Also, trypsin is able to degrade the capsid precursor but has no effect on VP33 and VP38 proteins when assembled into virus particles. These studies provide the basis for advancement of the knowledge of astrovirus VA1 cell entry and replication. IMPORTANCE Human astrovirus VA1 has been associated with neurological disease in immunocompromised patients. Its recent propagation in cell culture has facilitated the study of its biology. In this work, we show that despite the ability of this virus to grow in the absence of trypsin, a marked feature of human classical astroviruses, the capsid precursor protein of astrovirus VA1 is cleaved intracellularly to yield the mature infectious particles, formed by two polypeptides, VP33 that constitutes the core domain of the virus particle, and VP38 that forms the spike of the virus. These studies provide a platform to advance our knowledge on astrovirus VA1 cell entry and replication.
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Zhang W, Wang W, Liu X, Chen Y, Ouyang K, Wei Z, Liu H, Huang W. Identification of novel B-cell epitopes on the capsid protein of type 1 porcine astrovirus, using monoclonal antibodies. Int J Biol Macromol 2021; 189:939-947. [PMID: 34464644 DOI: 10.1016/j.ijbiomac.2021.08.129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 08/06/2021] [Accepted: 08/17/2021] [Indexed: 10/20/2022]
Abstract
Porcine astrovirus (PAstV) is prevalent in pigs worldwide and could cause clinical symptoms such as diarrhea and encephalitis. The capsid protein (Cap) of PAstV plays a determinant role for virus immunological characteristics. In this study, the major antigenic regions of PAstV1 Cap were expressed through prokaryotic expression systems and immunized to BALB/c mice. Finally, two anti-Cap monoclonal antibodies (named mAb F4-4 and D3F10) were screened by indirect immune-fluorescence assay (IFA). A series of truncated GST-fused or artificially synthesized peptides were used to detect their reactivity with the mAbs and PAstV positive serum. Two novel B cell epitopes (120-GNNTFG-125, 485-RISDPTWFSA-494) were identified by using these two mAbs. Moreover, sequence alignment result showed that epitope 120-GNNTFG-125 was highly conserved in type 1 PAstV capsid protein. Cross-reactivity analysis further confirmed the genotype-specificity of mAb F4-4. The results of this study demonstrated to be the first description of monoclonal antibody preparation and B-cell epitope mapping on PAstV capsid protein, which may provide new information on the biological significance of PAstV capsid protein and lay a foundation for the development of PAstV immunological tests and genotype diagnostic methods.
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Affiliation(s)
- Wenchao Zhang
- College of Animal Science and Technology, Guangxi University, No. 100 Daxue Road, Nanning 530005, China
| | - Weiyi Wang
- College of Animal Science and Technology, Guangxi University, No. 100 Daxue Road, Nanning 530005, China
| | - Xin Liu
- College of Animal Science and Technology, Guangxi University, No. 100 Daxue Road, Nanning 530005, China
| | - Ying Chen
- College of Animal Science and Technology, Guangxi University, No. 100 Daxue Road, Nanning 530005, China
| | - Kang Ouyang
- College of Animal Science and Technology, Guangxi University, No. 100 Daxue Road, Nanning 530005, China
| | - Zuzhang Wei
- College of Animal Science and Technology, Guangxi University, No. 100 Daxue Road, Nanning 530005, China
| | - Huan Liu
- Department of Scientific Research, The First Affiliated Hospital of Guangxi University of Chinese Medicine, No. 89-9 Dongge Road, Nanning 530024, China.
| | - Weijian Huang
- College of Animal Science and Technology, Guangxi University, No. 100 Daxue Road, Nanning 530005, China.
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Ykema M, Tao YJ. Structural Insights into the Human Astrovirus Capsid. Viruses 2021; 13:v13050821. [PMID: 34062934 PMCID: PMC8147390 DOI: 10.3390/v13050821] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/26/2021] [Accepted: 04/28/2021] [Indexed: 12/11/2022] Open
Abstract
Astroviruses (AstVs) are non-enveloped, positive single-stranded RNA viruses that cause a wide range of inflammatory diseases in mammalian and avian hosts. The T = 3 viral capsid is unique in its ability to infect host cells in a process driven by host proteases. Intercellular protease cleavages allow for viral egress from a cell, while extracellular cleavages allow for the virus to enter a new host cell to initiate infection. High-resolution models of the capsid core indicate a large, exposed region enriched with protease cleavage sites. The virus spike protein allows for binding to target cells and is the major target for naturally occurring and engineered neutralizing antibodies. During maturation, the capsid goes through significant structural changes including the loss of many surface spikes. The capsid interacts with host membranes during the virus life cycle at multiple stages such as assembly, host cell entry and exit. This review will cover recent findings and insights related to the structure of the capsid and its function. Further understanding of the viral capsid structure and maturation process can contribute to new vaccines, gastric therapeutics, and viral engineering applications.
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Aguilar-Hernández N, Meyer L, López S, DuBois RM, Arias CF. Protein Disulfide Isomerase A4 Is Involved in Genome Uncoating during Human Astrovirus Cell Entry. Viruses 2020; 13:v13010053. [PMID: 33396308 PMCID: PMC7824429 DOI: 10.3390/v13010053] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 12/18/2020] [Accepted: 12/21/2020] [Indexed: 02/07/2023] Open
Abstract
Although human astroviruses (HAstVs) are important agents of gastroenteritis in young children, the studies aimed at characterizing their biology have been limited, in particular regarding their cell entry process. It has been shown that HAstV serotype 8 enters human cells by a classical clathrin-mediated endocytosis pathway; however, the cell receptor or other cell entry factors that may be relevant for an efficient viral infection are unknown. In this work we used a far-Western blotting approach to identify cellular proteins that interact with the recombinant capsid spike proteins of HAstV serotypes 1, 2, and 8, synthesized in Escherichia coli. We identified the 72 kDa protein disulfide isomerase A4 (PDIA4) as a binding partner for HAstV-1 and -8 spikes, but not for the HAstV-2 spike. In agreement with this observation, the PDI inhibitor 16F16 strongly blocked infection by HAstV serotypes 1 and 8, but not serotype 2. RNA interference of PDIA4 expression selectively blocked HAstV-8 infectivity. We also showed that the PDI activity does not affect virus binding or internalization but is required for uncoating of the viral genome.
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Affiliation(s)
- Nayeli Aguilar-Hernández
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca CP 62210, Mexico; (N.A.-H.); (S.L.)
| | - Lena Meyer
- Department of Biomolecular Engineering, University of California, Santa Cruz, CA 95064, USA; (L.M.); (R.M.D.)
| | - Susana López
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca CP 62210, Mexico; (N.A.-H.); (S.L.)
| | - Rebecca M. DuBois
- Department of Biomolecular Engineering, University of California, Santa Cruz, CA 95064, USA; (L.M.); (R.M.D.)
| | - Carlos F. Arias
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca CP 62210, Mexico; (N.A.-H.); (S.L.)
- Correspondence:
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Sandoval-Jaime C. Astrovirus reverse genetics systems, a story of success. Curr Opin Virol 2020; 44:57-65. [PMID: 32683123 DOI: 10.1016/j.coviro.2020.06.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/18/2020] [Accepted: 06/19/2020] [Indexed: 12/13/2022]
Abstract
Astroviruses are one of the main causes of gastroenteritis of medical and veterinary relevance worldwide. Recently, these viruses were associated with neurological disease in mammals, including humans. Reverse genetics systems are the most powerful tool to improve our understanding of the virus replication, and eventually to develop safe vaccine candidates. In the present review, it is summarized the current knowledge on the different strategies used to develop reverse genetics systems for mamastroviruses and avastroviruses, and some of the biological answers that have provided are discussed.
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Affiliation(s)
- Carlos Sandoval-Jaime
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, UNAM, Cuernavaca, Morelos 62210, Mexico.
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12
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Isolation of Neutralizing Monoclonal Antibodies to Human Astrovirus and Characterization of Virus Variants That Escape Neutralization. J Virol 2019; 93:JVI.01465-18. [PMID: 30355681 DOI: 10.1128/jvi.01465-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 10/13/2018] [Indexed: 01/28/2023] Open
Abstract
Human astroviruses (HAstVs) cause severe diarrhea and represent an important health problem in children under two years of age. Despite their medical importance, the study of these pathogens has been neglected. To better understand the astrovirus antigenic structure and the basis of protective immunity, in this work we produced a panel of neutralizing monoclonal antibodies (Nt-MAbs) to HAstV serotypes 1, 2, and 8 and identified the mutations that allow the viruses to escape neutralization. We first tested the capacity of the recombinant HAstV capsid core and spike domains to elicit Nt-Abs. Hyperimmunization of animals with the two domains showed that although both induced a potent immune response, only the spike was able to elicit antibodies with neutralizing activity. Based on this finding, we used a mixture of the recombinant spike domains belonging to the three HAstV serotypes to immunize mice. Five Nt-MAbs were isolated and characterized; all of them were serotype specific, two were directed to HAstV-1, one was directed to HAstV-2, and two were directed to HAstV-8. These antibodies were used to select single and double neutralization escape variant viruses, and determination of the amino acid changes that allow the viruses to escape neutralization permitted us to define the existence of four potentially independent neutralization epitopes on the HAstV capsid. These studies provide the basis for development of subunit vaccines that induce neutralizing antibodies and tools to explore the possibility of developing a specific antibody therapy for astrovirus disease. Our results also establish a platform to advance our knowledge on HAstV cell binding and entry.IMPORTANCE Human astroviruses (HAstVs) are common etiological agents of acute gastroenteritis in children, the elderly, and immunocompromised patients; some virus strains have also been associated with neurological disease. Despite their medical importance, the study of these pathogens has advanced at a slow pace. In this work, we produced neutralizing antibodies to the virus and mapped the epitopes they recognize on the virus capsid. These studies provide the basis for development of subunit vaccines that induce neutralizing antibodies, as well as tools to explore the development of a specific antibody therapy for astrovirus disease. Our results also establish a platform to advance our knowledge on HAstV cell binding and entry.
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