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Omatola CA, Mshelbwala PP, Okolo MLO, Onoja AB, Abraham JO, Adaji DM, Samson SO, Okeme TO, Aminu RF, Akor ME, Ayeni G, Muhammed D, Akoh PQ, Ibrahim DS, Edegbo E, Yusuf L, Ocean HO, Akpala SN, Musa OA, Adamu AM. Noroviruses: Evolutionary Dynamics, Epidemiology, Pathogenesis, and Vaccine Advances-A Comprehensive Review. Vaccines (Basel) 2024; 12:590. [PMID: 38932319 PMCID: PMC11209302 DOI: 10.3390/vaccines12060590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 05/20/2024] [Accepted: 05/22/2024] [Indexed: 06/28/2024] Open
Abstract
Noroviruses constitute a significant aetiology of sporadic and epidemic gastroenteritis in human hosts worldwide, especially among young children, the elderly, and immunocompromised patients. The low infectious dose of the virus, protracted shedding in faeces, and the ability to persist in the environment promote viral transmission in different socioeconomic settings. Considering the substantial disease burden across healthcare and community settings and the difficulty in controlling the disease, we review aspects related to current knowledge about norovirus biology, mechanisms driving the evolutionary trends, epidemiology and molecular diversity, pathogenic mechanism, and immunity to viral infection. Additionally, we discuss the reservoir hosts, intra-inter host dynamics, and potential eco-evolutionary significance. Finally, we review norovirus vaccines in the development pipeline and further discuss the various host and pathogen factors that may complicate vaccine development.
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Affiliation(s)
- Cornelius Arome Omatola
- Department of Microbiology, Kogi State University, Anyigba 272102, Kogi State, Nigeria; (C.A.O.)
| | | | | | - Anyebe Bernard Onoja
- Department of Virology, University College Hospital, Ibadan 211101, Oyo State, Nigeria
| | - Joseph Oyiguh Abraham
- Department of Microbiology, Kogi State University, Anyigba 272102, Kogi State, Nigeria; (C.A.O.)
| | - David Moses Adaji
- Department of Biotechnology Science and Engineering, University of Alabama, Huntsville, AL 35899, USA
| | - Sunday Ocholi Samson
- Department of Molecular Biology, Biotechnology, and Biochemistry, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 29, 50-370 Wrocław, Poland
| | - Therisa Ojomideju Okeme
- Department of Biological Sciences, Federal University Lokoja, Lokoja 260101, Kogi State, Nigeria
| | - Ruth Foluke Aminu
- Department of Microbiology, Kogi State University, Anyigba 272102, Kogi State, Nigeria; (C.A.O.)
| | - Monday Eneojo Akor
- Department of Microbiology, Kogi State University, Anyigba 272102, Kogi State, Nigeria; (C.A.O.)
| | - Gideon Ayeni
- Department of Biochemistry, Kogi State University, Anyigba 272102, Kogi State, Nigeria
| | - Danjuma Muhammed
- Epidemiology and Public Health Unit, Department of Biology, Universiti Putra, Seri Kembangan 43300, Malaysia
| | - Phoebe Queen Akoh
- Department of Microbiology, Kogi State University, Anyigba 272102, Kogi State, Nigeria; (C.A.O.)
| | | | - Emmanuel Edegbo
- Department of Microbiology, Kogi State University, Anyigba 272102, Kogi State, Nigeria; (C.A.O.)
| | - Lamidi Yusuf
- Department of Microbiology, Kogi State University, Anyigba 272102, Kogi State, Nigeria; (C.A.O.)
| | | | - Sumaila Ndah Akpala
- Department of Microbiology, Kogi State University, Anyigba 272102, Kogi State, Nigeria; (C.A.O.)
- Department of Biotechnology, Federal University Lokoja, Lokoja 260101, Kogi State, Nigeria
| | - Oiza Aishat Musa
- Department of Microbiology, Kogi State University, Anyigba 272102, Kogi State, Nigeria; (C.A.O.)
| | - Andrew Musa Adamu
- Australian Institute of Tropical Health and Medicine, James Cook University, Townsville 4811, QLD, Australia
- College of Public Health Medical and Veterinary Sciences, James Cook University, Townsville 4811, QLD, Australia
- Centre for Tropical Biosecurity, James Cook University, Townsville 4811, QLD, Australia
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Chadwick PR, Trainor E, Marsden GL, Mills S, Chadwick C, O'Brien SJ, Evans CM, Mullender C, Strazds P, Turner S, Weston V, Toleman MS, de Barros C, Kontkowski G, Bak A. Guidelines for the management of norovirus outbreaks in acute and community health and social care settings. J Hosp Infect 2023:S0195-6701(23)00043-9. [PMID: 36796728 DOI: 10.1016/j.jhin.2023.01.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 01/19/2023] [Accepted: 01/22/2023] [Indexed: 02/17/2023]
Affiliation(s)
| | - Eamonn Trainor
- Northern Care Alliance NHS Foundation Trust, Greater Manchester, UK.
| | - Gemma L Marsden
- Healthcare Infection Society, London, UK; Royal College of General Practitioners, London, UK
| | - Samuel Mills
- British Infection Association, Seafield, West Lothian, UK; Oxford University NHS Foundation Trust, Oxford, UK
| | | | | | - Cariad M Evans
- Sheffield Teaching Hospital NHS Foundation Trust, Sheffield, UK
| | | | - Pixy Strazds
- Infection Prevention Society, London, UK; St Andrew's Healthcare, Northampton, UK
| | - Sarah Turner
- Infection Prevention Society, London, UK; Stockport Council, Stockport, UK
| | - Valya Weston
- Healthcare Infection Society, London, UK; Infection Prevention Society, London, UK; NHS England, London, UK
| | - Michelle S Toleman
- Healthcare Infection Society, London, UK; Cambridge University Hospitals NHS Trust, Cambridge, UK
| | | | | | - Aggie Bak
- Healthcare Infection Society, London, UK
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Zweigart MR, Becker-Dreps S, Bucardo F, González F, Baric RS, Lindesmith LC. Serological Humoral Immunity Following Natural Infection of Children with High Burden Gastrointestinal Viruses. Viruses 2021; 13:2033. [PMID: 34696463 PMCID: PMC8538683 DOI: 10.3390/v13102033] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 10/01/2021] [Accepted: 10/03/2021] [Indexed: 12/14/2022] Open
Abstract
Acute gastroenteritis (AGE) is a major cause of morbidity and mortality worldwide, resulting in an estimated 440,571 deaths of children under age 5 annually. Rotavirus, norovirus, and sapovirus are leading causes of childhood AGE. A successful rotavirus vaccine has reduced rotavirus hospitalizations by more than 50%. Using rotavirus as a guide, elucidating the determinants, breath, and duration of serological antibody immunity to AGE viruses, as well as host genetic factors that define susceptibility is essential for informing development of future vaccines and improving current vaccine candidates. Here, we summarize the current knowledge of disease burden and serological antibody immunity following natural infection to inform further vaccine development for these three high-burden viruses.
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Affiliation(s)
- Mark R. Zweigart
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC 27599, USA; (M.R.Z.); (S.B.-D.)
| | - Sylvia Becker-Dreps
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC 27599, USA; (M.R.Z.); (S.B.-D.)
- Department of Family Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Filemón Bucardo
- Department of Microbiology, National Autonomous University of Nicaragua, León 21000, Nicaragua; (F.B.); (F.G.)
| | - Fredman González
- Department of Microbiology, National Autonomous University of Nicaragua, León 21000, Nicaragua; (F.B.); (F.G.)
| | - Ralph S. Baric
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC 27599, USA; (M.R.Z.); (S.B.-D.)
| | - Lisa C. Lindesmith
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC 27599, USA; (M.R.Z.); (S.B.-D.)
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Grammatikos A, Donati M, Johnston SL, Gompels MM. Peripheral B Cell Deficiency and Predisposition to Viral Infections: The Paradigm of Immune Deficiencies. Front Immunol 2021; 12:731643. [PMID: 34527001 PMCID: PMC8435594 DOI: 10.3389/fimmu.2021.731643] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Accepted: 08/09/2021] [Indexed: 12/11/2022] Open
Abstract
In the era of COVID-19, understanding how our immune system responds to viral infections is more pertinent than ever. Immunodeficiencies with very low or absent B cells offer a valuable model to study the role of humoral immunity against these types of infection. This review looks at the available evidence on viral infections in patients with B cell alymphocytosis, in particular those with X-linked agammaglobulinemia (XLA), Good’s syndrome, post monoclonal-antibody therapy and certain patients with Common Variable Immune Deficiency (CVID). Viral infections are not as infrequent as previously thought in these conditions and individuals with very low circulating B cells seem to be predisposed to an adverse outcome. Particularly in the case of SARS-CoV2 infection, mounting evidence suggests that peripheral B cell alymphocytosis is linked to a poor prognosis.
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Affiliation(s)
- Alexandros Grammatikos
- Department of Immunology, Southmead Hospital, North Bristol National Health Service (NHS) Trust, Bristol, United Kingdom
| | - Matthew Donati
- Severn Infection Sciences and Public Health England National Infection Service South West, Department of Virology, Southmead Hospital, North Bristol NHS Trust, Bristol, United Kingdom
| | - Sarah L Johnston
- Department of Immunology, Southmead Hospital, North Bristol National Health Service (NHS) Trust, Bristol, United Kingdom
| | - Mark M Gompels
- Department of Immunology, Southmead Hospital, North Bristol National Health Service (NHS) Trust, Bristol, United Kingdom
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Kondapi DS, Ramani S, Estes MK, Atmar RL, Okhuysen PC. Norovirus in Cancer Patients: A Review. Open Forum Infect Dis 2021; 8:ofab126. [PMID: 34189156 PMCID: PMC8232388 DOI: 10.1093/ofid/ofab126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 03/10/2021] [Indexed: 12/15/2022] Open
Abstract
Norovirus (NoV) is the leading cause of viral-related diarrhea in cancer patients, in whom it can be chronic, contributing to decreased quality of life, interruption of cancer care, malnutrition, and altered mucosal barrier function. Immunosuppressed cancer patients shed NoV for longer periods of time than immunocompetent hosts, favoring quasispecies development and emergence of novel NoV variants. While nucleic acid amplification tests (NAATs) for NoV diagnosis have revolutionized our understanding of NoV burden of disease, not all NAATs provide information on viral load or infecting genotype. There is currently no effective antiviral or vaccine for chronic NoV infections. Screening for inhibitors of NoV replication in intestinal organoid culture models and creation of NoV-specific adoptive T cells are promising new strategies to develop treatments for chronic NoV in immunosuppressed patients. Herein we summarize data on the epidemiology, clinical manifestations, diagnostic challenges, and treatment of NoV infection in patients with cancer.
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Affiliation(s)
- Divya Samantha Kondapi
- Department of Infectious Diseases, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Section of Infectious Diseases, Baylor College of Medicine, Houston, Texas, USA
| | - Sasirekha Ramani
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Mary K Estes
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Robert L Atmar
- Section of Infectious Diseases, Baylor College of Medicine, Houston, Texas, USA
| | - Pablo C Okhuysen
- Infection Control and Employee Health, Division of Internal Medicine, Department of Infectious Diseases, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
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Cates JE, Vinjé J, Parashar U, Hall AJ. Recent advances in human norovirus research and implications for candidate vaccines. Expert Rev Vaccines 2020; 19:539-548. [PMID: 32500763 PMCID: PMC10760411 DOI: 10.1080/14760584.2020.1777860] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 06/01/2020] [Indexed: 12/13/2022]
Abstract
INTRODUCTION Noroviruses are a leading cause of acute gastroenteritis worldwide. An estimated 21 million illnesses in the United States and upwards of 684 million illnesses worldwide are attributed to norovirus infection. There are no licensed vaccines to prevent norovirus, but several candidates are in development. AREAS COVERED We review recent advances in molecular epidemiology of noroviruses, immunology, and in-vitro cultivation of noroviruses using human intestinal enteroids. We also provide an update on the status of norovirus vaccine candidates. EXPERT OPINION Molecular epidemiological studies confirm the tremendous genetic diversity of noroviruses, the continuous emergence of new recombinant strains, and the predominance of GII.4 viruses worldwide. Duration of immunity, extent of cross protection between different genotypes, and differences in strain distribution for young children compared with adults remain key knowledge gaps. Recent discoveries regarding which epitopes are targeted by neutralizing antibodies using the novel in vitro culture of human noroviruses in human intestinal enteroids are enhancing our understanding of mechanisms of protection and providing guidance for vaccine development. A future norovirus vaccine has the potential to substantially reduce the burden of illnesses due to this ubiquitous virus.
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Affiliation(s)
- Jordan E Cates
- Division of Viral Diseases, Centers for Disease Control and Prevention , Atlanta, GA, USA
- Epidemic Intelligence Service, Centers for Disease Control and Prevention , Atlanta, GA, USA
| | - Jan Vinjé
- Division of Viral Diseases, Centers for Disease Control and Prevention , Atlanta, GA, USA
| | - Umesh Parashar
- Division of Viral Diseases, Centers for Disease Control and Prevention , Atlanta, GA, USA
| | - Aron J Hall
- Division of Viral Diseases, Centers for Disease Control and Prevention , Atlanta, GA, USA
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Abstract
PURPOSE OF REVIEW Noroviruses are a major cause of gastroenteritis. This review summarizes new information on noroviruses that may lead to the development of improved measures for limiting their human health impact. RECENT FINDINGS GII.4 strains remain the most common human noroviruses causing disease, although GII.2 and GII.17 strains have recently emerged as dominant strains in some populations. Histo-blood group antigen (HBGA) expression on the gut mucosa drives susceptibility to different norovirus strains. Antibodies that block virus binding to these glycans correlate with protection from infection and illness. Immunocompromised patients are significantly impacted by norovirus infection, and the increasing availability of molecular diagnostics has improved infection recognition. Human noroviruses can be propagated in human intestinal enteroid cultures containing enterocytes that are a significant primary target for initiating infection. Strain-specific requirements for replication exist with bile being essential for some strains. Several vaccine candidates are progressing through preclinical and clinical development and studies of potential antiviral interventions are underway. SUMMARY Norovirus epidemiology is complex and requires continued surveillance to track the emergence of new strains and recombinants, especially with the continued progress in vaccine development. Humans are the best model to study disease pathogenesis and prevention. New in-vitro cultivation methods should lead to better approaches for understanding virus-host interactions and ultimately to improved strategies for mitigation of human norovirus-associated disease.
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The Antigenic Topology of Norovirus as Defined by B and T Cell Epitope Mapping: Implications for Universal Vaccines and Therapeutics. Viruses 2019; 11:v11050432. [PMID: 31083353 PMCID: PMC6563215 DOI: 10.3390/v11050432] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 05/07/2019] [Accepted: 05/08/2019] [Indexed: 12/11/2022] Open
Abstract
Human norovirus (HuNoV) is the leading cause of acute nonbacterial gastroenteritis. Vaccine design has been confounded by the antigenic diversity of these viruses and a limited understanding of protective immunity. We reviewed 77 articles published since 1988 describing the isolation, function, and mapping of 307 unique monoclonal antibodies directed against B cell epitopes of human and murine noroviruses representing diverse Genogroups (G). Of these antibodies, 91, 153, 21, and 42 were reported as GI-specific, GII-specific, MNV GV-specific, and G cross-reactive, respectively. Our goal was to reconstruct the antigenic topology of noroviruses in relationship to mapped epitopes with potential for therapeutic use or inclusion in universal vaccines. Furthermore, we reviewed seven published studies of norovirus T cell epitopes that identified 18 unique peptide sequences with CD4- or CD8-stimulating activity. Both the protruding (P) and shell (S) domains of the major capsid protein VP1 contained B and T cell epitopes, with the majority of neutralizing and HBGA-blocking B cell epitopes mapping in or proximal to the surface-exposed P2 region of the P domain. The majority of broadly reactive B and T cell epitopes mapped to the S and P1 arm of the P domain. Taken together, this atlas of mapped B and T cell epitopes offers insight into the promises and challenges of designing universal vaccines and immunotherapy for the noroviruses.
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Bányai K, Estes MK, Martella V, Parashar UD. Viral gastroenteritis. Lancet 2018; 392:175-186. [PMID: 30025810 PMCID: PMC8883799 DOI: 10.1016/s0140-6736(18)31128-0] [Citation(s) in RCA: 257] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 05/09/2018] [Accepted: 05/15/2018] [Indexed: 12/20/2022]
Abstract
Enteric viruses, particularly rotaviruses and noroviruses, are a leading cause of gastroenteritis worldwide. Rotaviruses primarily affect young children, accounting for almost 40% of hospital admissions for diarrhoea and 200 000 deaths worldwide, with the majority of deaths occurring in developing countries. Two vaccines against rotavirus were licensed in 2006 and have been implemented in 95 countries as of April, 2018. Data from eight high-income and middle-income countries showed a 49-89% decline in rotavirus-associated hospital admissions and a 17-55% decline in all-cause gastroenteritis-associated hospital admissions among children younger than 5 years, within 2 years of vaccine introduction. Noroviruses affect people of all ages, and are a leading cause of foodborne disease and outbreaks of gastroenteritis worldwide. Prevention of norovirus infection relies on frequent hand hygiene, limiting contact with people who are infected with the virus, and disinfection of contaminated environmental surfaces. Norovirus vaccine candidates are in clinical trials; whether vaccines will provide durable protection against the range of genetically and antigenically diverse norovirus strains remains unknown. Treatment of viral gastroenteritis is based primarily on replacement of fluid and electrolytes.
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Affiliation(s)
- Krisztián Bányai
- Institute for Veterinary Medical Research, Centre for Agricultural Research, Hungarian Academy of Sciences, Budapest, Hungary.
| | - Mary K Estes
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Vito Martella
- Department of Veterinary Medicine, University Aldo Moro of Bari, Provincial Road to Casamassima, Valenzano, Italy
| | - Umesh D Parashar
- Viral Gastroenteritis Branch, Division of Viral Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA
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He T, McMillen TA, Qiu Y, Chen LH, Lu X, Pang XL, Kamboj M, Tang YW. Norovirus Loads in Stool Specimens of Cancer Patients with Norovirus Gastroenteritis. J Mol Diagn 2017; 19:836-842. [PMID: 28807813 DOI: 10.1016/j.jmoldx.2017.06.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 05/25/2017] [Accepted: 06/22/2017] [Indexed: 11/15/2022] Open
Abstract
In immunocompromised patients with norovirus (NoV) gastroenteritis, the relationship between fecal NoV load and clinical complications has not been examined. In this study, a validated real-time quantitative PCR assay was used to determine viral loads for NoV genogroup I and II (GI and GII) in NoV-positive stool specimens of cancer patients. A total of 234 specimens from 152 patients were positive for NoV, including 201 of GII and 33 of GI. Geometric mean of logarithmic copies per gram of stool (w/w) of NoV-GII were 9.03 ± 1.71 (means ± SD), which was significantly higher than that of NoV-GI [7.87 ± 1.49; odd ratio (OR), 3.22; 95% CI, 1.33-7.76; P = 0.009]. Among 152 patients with gastroenteritis, the fecal NoV geometric mean of logarithmic copy was correlated with mild (n = 85; 7.97 ± 1.55), moderate (n = 23; 9.09 ± 1.38), and severe (n = 44; 10.39 ± 0.91) episodes of severity by modified Vesikari scoring system, respectively. Multivariate analysis revealed that high level of NoV load was correlated with GII infections (OR, 4.13; 95% CI, 1.62-10.55; P = 0.003) and associated with development of severe clinical symptom (OR, 5.53; 95% CI, 2.00-7.24; P = 0.001) at the time of diagnosis. Infection with GII strains was more common than GI infection in cancer patients with viral gastroenteritis.
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Affiliation(s)
- Taojun He
- Department of Laboratory Medicine, Eighth Affiliated Hospital of Sun Yat-Sen University, Shenzhen, China; Department of Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Tracy A McMillen
- Department of Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Yuanyuan Qiu
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - Liang Hua Chen
- Department of Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Xuedong Lu
- Department of Laboratory Medicine, Eighth Affiliated Hospital of Sun Yat-Sen University, Shenzhen, China
| | - Xiao-Li Pang
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada; Alberta Provincial Laboratory for Public Health, Edmonton, Alberta, Canada
| | - Mini Kamboj
- Department of Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, New York; Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, New York
| | - Yi-Wei Tang
- Department of Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, New York; Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, New York.
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Structural basis for norovirus neutralization by an HBGA blocking human IgA antibody. Proc Natl Acad Sci U S A 2016; 113:E5830-E5837. [PMID: 27647885 DOI: 10.1073/pnas.1609990113] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Human noroviruses (HuNoVs) cause sporadic and epidemic gastroenteritis worldwide. They are classified into two major genogroups (GI and GII), with each genogroup further divided into multiple genotypes. Susceptibility to these viruses is influenced by genetically determined histo-blood group antigen (HBGA) expression. HBGAs function as cell attachment factors by binding to a surface-exposed region in the protruding (P) domain of the capsid protein. Sequence variations in this region that result in differential HBGA binding patterns and antigenicity are suggested to form a basis for strain diversification. Recent studies show that serum antibodies that block HBGA binding correlate with protection against illness. Although genogroup-dependent variation in HBGA binding specificity is structurally well characterized, an understanding of how antibodies block HBGA binding and how genotypic variations affect such blockade is lacking. Our crystallographic studies of the GI.1 P domain in complex with the Fab fragment of a human IgA monoclonal antibody (IgA 5I2) with HBGA blocking activity show that the antibody recognizes a conformational epitope formed by two surface-exposed loop clusters in the P domain. The antibody engulfs the HBGA binding site but does not affect its structural integrity. An unusual feature of the antigen recognition by IgA 5I2 is the predominant involvement of the CDR light chain 1 in contrast to the commonly observed CDR heavy chain 3, providing a unique perspective into antibody diversity in antigen recognition. Identification of the antigenic site in the P domain shows how genotypic variations might allow escape from antibody neutralization and exemplifies the interplay between antigenicity and HBGA specificity in HuNoV evolution.
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