Human dengue virus serotype 2 neutralizing antibodies target two distinct quaternary epitopes

Abstract

Dengue virus (DENV) infection causes dengue fever, dengue hemorrhagic fever and dengue shock syndrome. It is estimated that a third of the world’s population is at risk for infection, with an estimated 390 million infections annually. Dengue virus serotype 2 (DENV2) causes severe epidemics, and the leading tetravalent dengue vaccine has lower efficacy against DENV2 compared to the other 3 serotypes. In natural DENV2 infections, strongly neutralizing type-specific antibodies provide protection against subsequent DENV2 infection. While the epitopes of some human DENV2 type-specific antibodies have been mapped, it is not known if these are representative of the polyclonal antibody response. Using structure-guided immunogen design and reverse genetics, we generated a panel of recombinant viruses containing amino acid alterations and epitope transplants between different serotypes. Using this panel of recombinant viruses in binding, competition, and neutralization assays, we have finely mapped the epitopes of three human DENV2 type-specific monoclonal antibodies, finding shared and distinct epitope regions. Additionally, we used these recombinant viruses and polyclonal sera to dissect the epitope-specific responses following primary DENV2 natural infection and monovalent vaccination. Our results demonstrate that antibodies raised following DENV2 infection or vaccination circulate as separate populations that neutralize by occupying domain III and domain I quaternary epitopes. The fraction of neutralizing antibodies directed to different epitopes differs between individuals. The identification of these epitopes could potentially be harnessed to evaluate epitope-specific antibody responses as correlates of protective immunity, potentially improving vaccine design.

Defining levels of dengue virus serotype-specific neutralizing antibodies induced by a live attenuated tetravalent dengue vaccine (TAK-003)

“…Twelve of the 15 subjects tested neutralized DENV4/2 (GMT=104) better than DENV4 alone, further implicating EDIII as a target of neutralizing Abs. We concluded that most subjects vaccinated with TAK-003 develop DENV2 TS NAbs that map to epitopes centered on EDIII, which is a major target of NAbs induced by WT DENV2 infections (29,33).…”

“…Previous studies by our group have demonstrated that some TS NAbs elicited after DENV2 natural infection map to quaternary antigenic regions/epitopes involving EDIII of the E protein (29,33). We used a recombinant chimeric rDENV4/2 virus displaying the DENV2 TS epitopes centered on EDIII on a DENV4 E protein backbone to map vaccine responses.…”

“…Gain of neutralization by the chimeric DENV4/2 virus over the parental DENV4 backbone was evidence of DENV2 neutralizing Abs targeting sites in EDIII. The properties of the chimeric and parental viruses used in this experiment are described elsewhere (29,33).…”

Adaptive Immunity to Dengue Virus: Slippery Slope or Solid Ground for Rational Vaccine Design?

“…Its prophylactic and therapeutic activity against DENV2 has been demonstrated in vivo [ 233 ]. Two other human mAbs that potently inhibit DENV2 have been described: 1L12, which, based on competition assays, binds an epitope partially overlapping with that of 2D22, and 3F9, which engages an epitope centred on EDI that might represent a potential second major neutralising site on DENV2 [ 110 , 234 ].…”

Characterization of a potent and highly unusual minimally enhancing antibody directed against dengue virus

“…2D22 or C8-EDE which bind roughly on the opposite face of EDIII ( Supplementary Fig. 5) 24,25,37,38 . Taken together, our comparison shows that while 2C8 targets the classical lateral ridge epitope, the 3H5 binding footprint extends to additional residues outside of this region.…”