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Bowman KA, Kaplonek P, McNamara RP. Understanding Fc function for rational vaccine design against pathogens. mBio 2024; 15:e0303623. [PMID: 38112418 PMCID: PMC10790774 DOI: 10.1128/mbio.03036-23] [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] [Indexed: 12/21/2023] Open
Abstract
Antibodies represent the primary correlate of immunity following most clinically approved vaccines. However, their mechanisms of action vary from pathogen to pathogen, ranging from neutralization, to opsonophagocytosis, to cytotoxicity. Antibody functions are regulated both by antigen specificity (Fab domain) and by the interaction of their Fc domain with distinct types of Fc receptors (FcRs) present in immune cells. Increasing evidence highlights the critical nature of Fc:FcR interactions in controlling pathogen spread and limiting the disease state. Moreover, variation in Fc-receptor engagement during the course of infection has been demonstrated across a range of pathogens, and this can be further influenced by prior exposure(s)/immunizations, age, pregnancy, and underlying health conditions. Fc:FcR functional variation occurs at the level of antibody isotype and subclass selection as well as post-translational modification of antibodies that shape Fc:FcR-interactions. These factors collectively support a model whereby the immune system actively harnesses and directs Fc:FcR interactions to fight disease. By defining the precise humoral mechanisms that control infections, as well as understanding how these functions can be actively tuned, it may be possible to open new paths for improving existing or novel vaccines.
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Affiliation(s)
- Kathryn A. Bowman
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, Massachusetts, USA
- Division of Infectious Diseases, Brigham and Women’s Hospital, Boston, Massachusetts, USA
| | - Paulina Kaplonek
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, Massachusetts, USA
| | - Ryan P. McNamara
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, Massachusetts, USA
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2
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Luo T, Patel JG, Zhang X, McBride JW. Antibody reactive immunomes of Ehrlichia chaffeensis and E. canis are diverse and defined by conformational antigenic determinants. Front Cell Infect Microbiol 2024; 13:1321291. [PMID: 38264730 PMCID: PMC10803646 DOI: 10.3389/fcimb.2023.1321291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 12/19/2023] [Indexed: 01/25/2024] Open
Abstract
For decades, the defined antibody reactive proteins of Ehrlichia chaffeensis and E. canis were limited to a small group with linear antibody epitopes. Recently, our laboratory has utilized an immunomics-based approach to rapidly screen and identify undefined Ehrlichia chaffeensis and E. canis antigenic proteins and antibody epitopes. In this study, we analyzed the remaining portion (~50%) of the E. chaffeensis and E. canis proteomes (n = 444 and n = 405 proteins, respectively), that were not examined in previous studies, to define the complete immunomes of these important pathogens. Almost half of the E. chaffeensis proteins screened (196/444) reacted with antibodies in convalescent HME patient sera, while only 43 E. canis proteins reacted with CME dog sera. New major immunoreactive proteins were identified in E. chaffeensis (n = 7) and E. canis (n = 1), increasing the total number of E. chaffeensis (n = 14) and E. canis proteins (n = 18) that exhibited antibody reactivity comparable to well-defined major antigenic proteins (TRP120 and TRP19). All of the E. chaffeensis but only some E. canis major immunoreactive proteins contained major conformation-dependent antibody epitopes. The E. chaffeensis immunoreactive proteins were generally small (< 250 amino acids; ~27kDa) and the E. canis proteins were slightly larger (> 320 amino acids; ~35 kDa). The majority of these new Ehrlichia major immunoreactive proteins were predicted to be type I secreted effectors, some of which contained transmembrane domains. Characterization of the immunomes of E. chaffeensis and E. canis and understanding the host specific Ehrlichia immune responses will facilitate identification of protective antigens and define the biophysical epitope characteristics vital to effective vaccine development for the ehrlichioses.
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Affiliation(s)
- Tian Luo
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Jignesh G. Patel
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Xiaofeng Zhang
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Jere W. McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX, United States
- Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, TX, United States
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States
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3
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Munt JE, Henein S, Adams C, Young E, Hou YJ, Conrad H, Zhu D, Dong S, Kose N, Yount B, Meganck RM, Tse LPV, Kuan G, Balmaseda A, Ricciardi MJ, Watkins DI, Crowe JE, Harris E, DeSilva AM, Baric RS. Homotypic antibodies target novel E glycoprotein domains after natural DENV 3 infection/vaccination. Cell Host Microbe 2023; 31:1850-1865.e5. [PMID: 37909048 PMCID: PMC11221912 DOI: 10.1016/j.chom.2023.10.004] [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: 03/01/2023] [Revised: 07/31/2023] [Accepted: 10/04/2023] [Indexed: 11/02/2023]
Abstract
The envelope (E) glycoprotein is the primary target of type-specific (TS) neutralizing antibodies (nAbs) after infection with any of the four distinct dengue virus serotypes (DENV1-4). nAbs can be elicited to distinct structural E domains (EDs) I, II, or III. However, the relative contribution of these domain-specific antibodies is unclear. To identify the primary DENV3 nAb targets in sera after natural infection or vaccination, chimeric DENV1 recombinant encoding DENV3 EDI, EDII, or EDIII were generated. DENV3 EDII is the principal target of TS polyclonal nAb responses and encodes two or more neutralizing epitopes. In contrast, some were individuals vaccinated with a DENV3 monovalent vaccine-elicited serum TS nAbs targeting each ED in a subject-dependent fashion, with an emphasis on EDI and EDIII. Vaccine responses were also sensitive to DENV3 genotypic variation. This DENV1/3 panel allows the measurement of serum ED TS nAbs, revealing differences in TS nAb immunity after natural infection or vaccination.
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Affiliation(s)
- Jennifer E Munt
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Sandra Henein
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC, USA
| | - Cameron Adams
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC, USA
| | - Ellen Young
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Yixuan J Hou
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Helen Conrad
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Deanna Zhu
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Stephanie Dong
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Nurgun Kose
- Vanderbilt Vaccine Center, Nashville, TN, USA
| | - Boyd Yount
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Rita M Meganck
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Long Ping V Tse
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Guillermina Kuan
- Health Center Socrates Flores Vivas, Ministry of Health, Managua, Nicaragua; Sustainable Sciences Institute, Managua, Nicaragua
| | - Angel Balmaseda
- Sustainable Sciences Institute, Managua, Nicaragua; National Virology Laboratory, National Center for Diagnosis and Reference, Ministry of Health, Managua, Nicaragua
| | | | - David I Watkins
- University of Massachusetts Medical School, Worcester, MA, USA
| | | | - Eva Harris
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California Berkeley, Berkeley, CA, USA
| | - Aravinda M DeSilva
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC, USA
| | - Ralph S Baric
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA; Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC, USA.
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4
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Meganck RM, Zhu D, Dong S, Snoderly-Foster LJ, Dalben YR, Thiono D, White LJ, DeSilva AM, Baric RS, Tse LV. Evolution of a functionally intact but antigenically distinct DENV fusion loop. eLife 2023; 12:RP87555. [PMID: 37725085 PMCID: PMC10508882 DOI: 10.7554/elife.87555] [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: 09/21/2023] Open
Abstract
A hallmark of dengue virus (DENV) pathogenesis is the potential for antibody-dependent enhancement, which is associated with deadly DENV secondary infection, complicates the identification of correlates of protection, and negatively impacts the safety and efficacy of DENV vaccines. Antibody-dependent enhancement is linked to antibodies targeting the fusion loop (FL) motif of the envelope protein, which is completely conserved in mosquito-borne flaviviruses and required for viral entry and fusion. In the current study, we utilized saturation mutagenesis and directed evolution to engineer a functional variant with a mutated FL (D2-FL), which is not neutralized by FL-targeting monoclonal antibodies. The FL mutations were combined with our previously evolved prM cleavage site to create a mature version of D2-FL (D2-FLM), which evades both prM- and FL-Abs but retains sensitivity to other type-specific and quaternary cross-reactive (CR) Abs. CR serum from heterotypic (DENV4)-infected non-human primates (NHP) showed lower neutralization titers against D2-FL and D2-FLM than isogenic wildtype DENV2 while similar neutralization titers were observed in serum from homotypic (DENV2)-infected NHP. We propose D2-FL and D2-FLM as valuable tools to delineate CR Ab subtypes in serum as well as an exciting platform for safer live-attenuated DENV vaccines suitable for naïve individuals and children.
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Affiliation(s)
- Rita M Meganck
- Department of Molecular Microbiology and Immunology, Saint Louis UniversitySaint LouisUnited States
| | - Deanna Zhu
- Department of Epidemiology, University of North Carolina at Chapel HillChapel HillUnited States
| | - Stephanie Dong
- Department of Epidemiology, University of North Carolina at Chapel HillChapel HillUnited States
| | - Lisa J Snoderly-Foster
- Department of Molecular Microbiology and Immunology, Saint Louis UniversitySaint LouisUnited States
| | - Yago R Dalben
- Department of Molecular Microbiology and Immunology, Saint Louis UniversitySaint LouisUnited States
| | - Devina Thiono
- Department of Microbiology, University of North Carolina at Chapel HillChapel HillUnited States
| | - Laura J White
- Department of Microbiology, University of North Carolina at Chapel HillChapel HillUnited States
| | - Arivianda M DeSilva
- Department of Microbiology, University of North Carolina at Chapel HillChapel HillUnited States
| | - Ralph S Baric
- Department of Epidemiology, University of North Carolina at Chapel HillChapel HillUnited States
| | - Longping V Tse
- Department of Molecular Microbiology and Immunology, Saint Louis UniversitySaint LouisUnited States
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5
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Meganck RM, Zhu D, Dong S, Snoderly-Foster LJ, Dalben YR, Thiono D, White LJ, DeSilva AM, Baric RS, Tse LV. Evolution of a Functionally Intact but Antigenically Distinct DENV Fusion Loop. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.22.533803. [PMID: 37034784 PMCID: PMC10081285 DOI: 10.1101/2023.03.22.533803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A hallmark of Dengue virus (DENV) pathogenesis is the potential for antibody-dependent enhancement, which is associated with deadly DENV secondary infection, complicates the identification of correlates of protection, and negatively impacts the safety and efficacy of DENV vaccines. ADE is linked to antibodies targeting the fusion loop (FL) motif of the envelope protein, which is completely conserved in mosquito-borne flaviviruses and required for viral entry and fusion. In the current study, we utilized saturation mutagenesis and directed evolution to engineer a functional variant with a mutated FL (D2-FL) which is not neutralized by FL-targeting monoclonal antibodies. The FL mutations were combined with our previously evolved prM cleavage site to create a mature version of D2-FL (D2-FLM), which evades both prM- and FL-Abs but retains sensitivity to other type-specific and quaternary cross-reactive (CR) Abs. CR serum from heterotypic (DENV4) infected non-human primates (NHP) showed lower neutralization titers against D2-FL and D2-FLM than isogenic wildtype DENV2 while similar neutralization titers were observed in serum from homotypic (DENV2) infected NHP. We propose D2-FL and D2-FLM as valuable tools to delineate CR Ab subtypes in serum as well as an exciting platform for safer live attenuated DENV vaccines suitable for naïve individuals and children.
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Affiliation(s)
- Rita M. Meganck
- Department of Molecular Microbiology and Immunology, Saint Louis University
| | - Deanna Zhu
- Department of Epidemiology, University of North Carolina at Chapel Hill
| | - Stephanie Dong
- Department of Epidemiology, University of North Carolina at Chapel Hill
| | | | - Yago R. Dalben
- Department of Molecular Microbiology and Immunology, Saint Louis University
| | - Devina Thiono
- Department of Microbiology, University of North Carolina at Chapel Hill
| | - Laura J. White
- Department of Microbiology, University of North Carolina at Chapel Hill
| | | | - Ralph S. Baric
- Department of Epidemiology, University of North Carolina at Chapel Hill
| | - Longping V. Tse
- Department of Molecular Microbiology and Immunology, Saint Louis University
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Immunoreactive Protein Repertoires of Ehrlichia chaffeensis and E. canis Reveal the Dominance of Hypothetical Proteins and Conformation-dependent Antibody Epitopes. Infect Immun 2021; 89:e0022421. [PMID: 34370510 DOI: 10.1128/iai.00224-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The immunomes of Ehrlichia chaffeensis (E. ch.) and E. canis (E. ca.) have recently be revised to include immunodominant hypothetical proteins with conformational antibody epitopes. In this study, we examined 216 E. ch. and 190 E. ca. highly antigenic proteins according to ANTIGENpro and also performed a genome-wide hypothetical protein analysis (E. ch. n=104; E. ca. n=124) for immunoreactivity. Using cell-free protein expression and immunoanalysis, 118 E. ch. and 39 E. ca. proteins reacted with sera from naturally E. ch.-infected patients or E. ca.-infected dogs. Moreover, 22 E. ch. and 18 E. ca. proteins consistently and strongly reacted with a panel of patient or canine sera. A subset of E. ch. (n=18) and E. ca. (n=9) proteins were identified as immunodominant. Consistent with our previous study, most proteins were classified as hypothetical and the antibody epitopes exhibited complete or partial conformation-dependence. The majority (28/40; 70%) of E. ch. and E. ca. proteins contained transmembrane domains and 19 (48%) were predicted to be secreted effectors. The antigenic repertoires of E. ch. and E. ca. were mostly diverse and suggest that the immunomes of these closely related ehrlichiae are dominated by species-specific conformational antibody epitopes. This study reveals a significant group of previously undefined E. ch. and E. ca. antigens and reaffirms the importance of conformation-dependent epitopes as targets of anti-Ehrlichia immune responses. These findings substantially expand our understanding of host-Ehrlichia immune responses, advance efforts to define the molecular features of protective proteins and improve prospects for effective vaccines for the ehrlichioses.
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Young E, Carnahan RH, Andrade DV, Kose N, Nargi RS, Fritch EJ, Munt JE, Doyle MP, White L, Baric TJ, Stoops M, DeSilva A, Tse LV, Martinez DR, Zhu D, Metz S, Wong MP, Espinosa DA, Montoya M, Biering SB, Sukulpolvi-Petty S, Kuan G, Balmaseda A, Diamond MS, Harris E, Crowe JE, Baric RS. Identification of Dengue Virus Serotype 3 Specific Antigenic Sites Targeted by Neutralizing Human Antibodies. Cell Host Microbe 2021; 27:710-724.e7. [PMID: 32407709 PMCID: PMC7309352 DOI: 10.1016/j.chom.2020.04.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/18/2020] [Accepted: 04/06/2020] [Indexed: 12/31/2022]
Abstract
The rational design of dengue virus (DENV) vaccines requires a detailed understanding of the molecular basis for antibody-mediated immunity. The durably protective antibody response to DENV after primary infection is serotype specific. However, there is an incomplete understanding of the antigenic determinants for DENV type-specific (TS) antibodies, especially for DENV serotype 3, which has only one well-studied, strongly neutralizing human monoclonal antibody (mAb). Here, we investigated the human B cell response in children after natural DENV infection in the endemic area of Nicaragua and isolated 15 DENV3 TS mAbs recognizing the envelope (E) glycoprotein. Functional epitope mapping of these mAbs and small animal prophylaxis studies revealed a complex landscape with protective epitopes clustering in at least 6-7 antigenic sites. Potently neutralizing TS mAbs recognized sites principally in E glycoprotein domains I and II, and patterns suggest frequent recognition of quaternary structures on the surface of viral particles.
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Affiliation(s)
- Ellen Young
- Department of Epidemiology, Gillings School of Public Health, University of North Carolina, Chapel Hill, NC, USA
| | - Robert H Carnahan
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Daniela V Andrade
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California Berkeley, Berkeley, CA, USA
| | - Nurgun Kose
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Rachel S Nargi
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Ethan J Fritch
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Jennifer E Munt
- Department of Epidemiology, Gillings School of Public Health, University of North Carolina, Chapel Hill, NC, USA
| | - Michael P Doyle
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Laura White
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Thomas J Baric
- Department of Epidemiology, Gillings School of Public Health, University of North Carolina, Chapel Hill, NC, USA
| | - Mark Stoops
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Aravinda DeSilva
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Longping V Tse
- Department of Epidemiology, Gillings School of Public Health, University of North Carolina, Chapel Hill, NC, USA
| | - David R Martinez
- Department of Epidemiology, Gillings School of Public Health, University of North Carolina, Chapel Hill, NC, USA
| | - Deanna Zhu
- Department of Epidemiology, Gillings School of Public Health, University of North Carolina, Chapel Hill, NC, USA
| | - Stefan Metz
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Marcus P Wong
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California Berkeley, Berkeley, CA, USA
| | - Diego A Espinosa
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California Berkeley, Berkeley, CA, USA
| | - Magelda Montoya
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California Berkeley, Berkeley, CA, USA
| | - Scott B Biering
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California Berkeley, Berkeley, CA, USA
| | - Soila Sukulpolvi-Petty
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Guillermina Kuan
- Health Center Sócrates Flores Vivas, Ministry of Health, Managua, Nicaragua
| | - Angel Balmaseda
- National Virology Laboratory, National Center for Diagnosis and Reference, Ministry of Health, Managua, Nicaragua
| | - Michael S Diamond
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA; Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110, USA; Pathology & Immunology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Eva Harris
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California Berkeley, Berkeley, CA, USA.
| | - James E Crowe
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA; Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Ralph S Baric
- Department of Epidemiology, Gillings School of Public Health, University of North Carolina, Chapel Hill, NC, USA; Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, NC, USA.
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Ehrlichia chaffeensis and E. canis hypothetical protein immunoanalysis reveals small secreted immunodominant proteins and conformation-dependent antibody epitopes. NPJ Vaccines 2020; 5:85. [PMID: 32963815 PMCID: PMC7486380 DOI: 10.1038/s41541-020-00231-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Accepted: 08/12/2020] [Indexed: 01/05/2023] Open
Abstract
Immunomolecular characterization of Ehrlichia chaffeensis (E. ch.) and E. canis (E. ca.) has defined protein orthologs, including tandem repeat proteins (TRPs) that have immunodominant linear antibody epitopes. In this study, we combined bioinformatic analysis and cell-free protein expression to identify undiscovered immunoreactive E. ch. and E. ca. hypothetical proteins. Antigenicity of the E. ch. and E. ca. ORFeomes (n = 1105 and n = 925, respectively) was analyzed by the sequence-based prediction model ANTIGENpro, and we identified ~250 ORFs in each respective ORFeome as highly antigenic. The hypothetical proteins (E. ch. n = 93 and E. ca. n = 98) present in the top 250 antigenic ORFs were further investigated in this study. By ELISA, 46 E. ch. and 30 E. ca. IVTT-expressed hypothetical proteins reacted with antibodies in sera from naturally E. ch.-infected patients or E. ca.-infected dogs. Moreover, 15 E. ch. and 16 E. ca. proteins consistently reacted with a panel of sera from patients or dogs, including many that revealed the immunoreactivity of “gold standard” TRPs. Antibody epitopes in most (>70%) of these proteins exhibited partial or complete conformation-dependence. The majority (23/31; 74%) of the major immunoreactive proteins identified were small (≤250 aa), and 20/31 (65%) were predicted to be secreted effectors. Unlike the strong linear antibody epitopes previously identified in TRP and OMP orthologs, there were contrasting differences in the E. ch. and E. ca. antigenic repertoires, epitopes and ortholog immunoreactivity. This study reveals numerous previously undefined immunodominant and subdominant antigens, and illustrates the breadth, complexity, and diversity of immunoreactive proteins/epitopes in Ehrlichia.
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Wilken L, Rimmelzwaan GF. Adaptive Immunity to Dengue Virus: Slippery Slope or Solid Ground for Rational Vaccine Design? Pathogens 2020; 9:pathogens9060470. [PMID: 32549226 PMCID: PMC7350362 DOI: 10.3390/pathogens9060470] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 06/11/2020] [Accepted: 06/12/2020] [Indexed: 12/15/2022] Open
Abstract
The four serotypes of dengue virus are the most widespread causes of arboviral disease, currently placing half of the human population at risk of infection. Pre-existing immunity to one dengue virus serotype can predispose to severe disease following secondary infection with a different serotype. The phenomenon of immune enhancement has complicated vaccine development and likely explains the poor long-term safety profile of a recently licenced dengue vaccine. Therefore, alternative vaccine strategies should be considered. This review summarises studies dissecting the adaptive immune responses to dengue virus infection and (experimental) vaccination. In particular, we discuss the roles of (i) neutralising antibodies, (ii) antibodies to non-structural protein 1, and (iii) T cells in protection and pathogenesis. We also address how these findings could translate into next-generation vaccine approaches that mitigate the risk of enhanced dengue disease. Finally, we argue that the development of a safe and efficacious dengue vaccine is an attainable goal.
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