Recognition determinants of broadly neutralizing human antibodies against dengue viruses.

Authors:
Rouvinski A, Guardado-Calvo P, Barba-Spaeth G, Duquerroy S, Vaney MC1, Kikuti CM, Navarro Sanchez ME, Dejnirattisai W, Wongwiwat W, Haouz A, Girard-Blanc C, Petres S, Shepard WE, Despr├Ęs P, Arenzana-Seisdedos F, Dussart P, Mongkolsapaya J, Screaton GR, Rey FA.
In:
Source: Nature
Publication Date: (2015)
Issue: 520(7545): 109-13
Research Area:
Gene Expression
Cells used in publication:
Schneider's Drosophila Line 2
Species: drosophila melanogaster (fruit fly)
Tissue Origin: embryo
Culture Media:
Experiment

Dengue disease is caused by four different flavivirus serotypes. Protein E, which is exposed at the surface of the mature Dengue Virus is the only source for neutralizing antibodies. A large fragment of E (termed sE for \"soluble E) crystallizes as a dimer mimicking the organization of Protein E in virons. The authors recently isolated human antibodies poetntly neutralizing all four dengue Vvrus serotype. In the reference, they describe the X-ray structure of four of these neutralizing antibodies in complex with the envelope glycoprotein E from Dengue Virus serotype 2. For this purpose, recombinant sE protein was cloned into a vector with a carboxy (C)-terminal His-tag and produced in Drosophila S2 cells. Briefly, sE expression was driven by the metallothionein promoter andwas induced by 5 mM of CdCl2 in Insect-XPRESS medium (Lonza). The purified DENV-2 SE Protein was mixed with Antigen binding (Fab) fragments of bnAbs. This complex was used for crystallization and three-dimensional structure determinations.

Abstract

Dengue disease is caused by four different flavivirus serotypes, which infect 390 million people yearly with 25% symptomatic cases and for which no licensed vaccine is available. Recent phase III vaccine trials showed partial protection, and in particular no protection for dengue virus serotype 2 (refs 3, 4). Structural studies so far have characterized only epitopes recognized by serotype-specific human antibodies. We recently isolated human antibodies potently neutralizing all four dengue virus serotypes. Here we describe the X-ray structures of four of these broadly neutralizing antibodies in complex with the envelope glycoprotein E from dengue virus serotype 2, revealing that the recognition determinants are at a serotype-invariant site at the E-dimer interface, including the exposed main chain of the E fusion loop and the two conserved glycan chains. This 'E-dimer-dependent epitope' is also the binding site for the viral glycoprotein prM during virus maturation in the secretory pathway of the infected cell, explaining its conservation across serotypes and highlighting an Achilles' heel of the virus with respect to antibody neutralization. These findings will be instrumental for devising novel immunogens to protect simultaneously against all four serotypes of dengue virus