Dengue virus serotype 2 envelope-domain antibody responses after primary infection in younger and older children

After primary dengue (DENV) infection or vaccination, individuals develop antibodies to different epitopes and domains on the DENV envelope (E) and pre-membrane (prM) glycoproteins. Of these, serotype-specific (TS) antibodies typically target E domains, while serotype cross-reactive (CR) antibodies typically target pre-membrane (prM) protein and conserved E regions. To identify and quantify E-domain, neutralizing TS antibody responses in polyclonal sera, we developed a panel of chimeric DENV4/2 viruses that incorporate DENV2 envelope-domain I, II, and III (DENV4/2-EDI, EDII, EDIII) into the DENV4 E glycoprotein. Chimeric DENV4/2 viruses were recovered, replicated efficiently, and displayed similar maturation states as parental viruses. The recovery of viable DENV4/2-EDII recombinants required the inclusion of chimeric DENV4/2 prM that maintained critical interactions with chimeric E. To assess structural integrity and epitope display of chimeric viruses, we examined neutralization of mature virions by monoclonal antibodies and heterotypic polyclonal sera. The ED-chimeric virions preserved epitopes of TS and envelope-dimer-epitope CR monoclonal antibodies and had similar sensitivity to CR polyclonal responses as parental strains. Primary sera from natural infection and human challenge targeted a region centered on EDIII and secondarily target EDII and EDI. Sera from natural infection had a unique neutralization pattern of the chimeric viruses compared to sera from human challenge, which included greater frequency and higher titer of responses against EDII. In a preliminary analysis of neutralizing antibodies in children 2-5 years old and 8-11 years after primary DENV2 infection, we observe decreased prevalence of DENV2 neutralization titers in younger children, and of those that mounted neutralizing responses, decreased prevalence of responses against EDII, though titers did not differ. In summary, our panel of DENV4/2 E-domain recombinant viruses delineates the subdomain targets of TS antibodies after primary infection. We see that polyclonal responses to DENV2 EDIII correlate closely with DENV2 neutralization across multiple populations and that responses to DENV2 EDII occurred in greater prevalence in groups associated with more robust immune responses. These findings provide evidence that ED-level DENV responses may be relevant correlates of protection against future DENV infection.