title: A new quaternary structure epitope on dengue virus serotype 2 is the target of durable type-specific neutralizing antibodies.
abstract: Dengue virus serotype 2 (DENV2) is widespread and responsible for severe epidemics. While primary DENV2 infections stimulate serotype-specific protective responses, a leading vaccine failed to induce a similar protective response. Using human monoclonal antibodies (hMAbs) isolated from dengue cases and structure-guided design of a chimeric DENV, here we describe the major site on the DENV2 envelope (E) protein targeted by neutralizing antibodies. DENV2-specific neutralizing hMAb 2D22 binds to a quaternary structure epitope. We engineered and recovered a recombinant DENV4 that displayed the 2D22 epitope. DENV2 neutralizing antibodies in people exposed to infection or a live vaccine tracked with the 2D22 epitope on the DENV4/2 chimera. The chimera remained sensitive to DENV4 antibodies, indicating that the major neutralizing epitopes on DENV2 and -4 are at different sites. The ability to transplant a complex epitope between DENV serotypes demonstrates a hitherto underappreciated structural flexibility in flaviviruses, which could be harnessed to develop new vaccines and diagnostics.
  
  
  OBJECTIVE
  Dengue virus causes fever and dengue hemorrhagic fever. Dengue serotype 2 (DENV2) is widespread and frequently responsible for severe epidemics. Natural DENV2 infections stimulate serotype-specific neutralizing antibodies, but a leading DENV vaccine did not induce a similar protective response. While groups have identified epitopes of single monoclonal antibodies (MAbs), the molecular basis of DENV2 neutralization by polyclonal human immune sera is unknown. Using a recombinant DENV displaying serotype 2 epitopes, here we map the main target of DENV2 polyclonal neutralizing antibodies induced by natural infection and a live DENV2 vaccine candidate. Proper display of the epitope required the assembly of viral envelope proteins into higher-order structures present on intact virions. Despite the complexity of the epitope, it was possible to transplant the epitope between DENV serotypes. Our findings have immediate implications for evaluating dengue vaccines in the pipeline as well as designing next-generation vaccines.
authors.affiliation: Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA.
authors.forename: E N
authors.initials: EN
authors.lastname: Gallichotte
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors.forename: D G
authors.initials: DG
authors.lastname: Widman
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors.forename: B L
authors.initials: BL
authors.lastname: Yount
authors.affiliation: Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA.
authors.forename: W M
authors.initials: WM
authors.lastname: Wahala
authors.affiliation: Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA.
authors.forename: A
authors.initials: A
authors.lastname: Durbin
authors.affiliation: Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: S
authors.initials: S
authors.lastname: Whitehead
authors.affiliation: Caribbean Primate Research Center, University of Puerto Rico-Medical Sciences Campus, San Juan, Puerto Rico, USA Department of Microbiology and Medical Zoology, University of Puerto Rico-Medical Sciences Campus, San Juan, Puerto Rico, USA Department of Internal Medicine, University of Puerto Rico-Medical Sciences Campus, San Juan, Puerto Rico, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Sariol
authors.affiliation: Department of Pediatrics and The Vanderbilt Vaccine Center, Vanderbilt University, Nashville, Tennessee, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Crowe
authors.affiliation: Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA aravinda_desilva@med.unc.edu rbaric@email.unc.edu.
authors.forename: A M
authors.initials: AM
authors.lastname: de Silva
authors.affiliation: Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA aravinda_desilva@med.unc.edu rbaric@email.unc.edu.
authors.forename: R S
authors.initials: RS
authors.lastname: Baric
mesh_terms: D057134:Antibodies, Neutralizing / Q000097:blood*; D000914:Antibodies, Viral / Q000097:blood*; D003716:Dengue Virus / Q000276:immunology*; D018985:Epitopes, B-Lymphocyte / Q000276:immunology*; D006801:Humans; D014759:Viral Envelope Proteins / Q000276:immunology*
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; C051821:E-glycoprotein, Dengue virus type 2; D018985:Epitopes, B-Lymphocyte; D014759:Viral Envelope Proteins