Dengue virus 4/2 envelope domain chimeric virus panel maps type-specific responses against dengue serotype 2

ABSTRACT The DENV envelope (E) and pre-membrane (prM) glycoproteins are primary targets of serologic immunity after infection and vaccination. Of these, serotype-specific (TS) antibodies typically target E domains, while serotype cross-reactive (CR) antibodies typically the target prM protein and conserved E regions. To identify and quantify E-domain TS neutralizing 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 (mAbs) and heterotypic polyclonal sera. The ED-chimeric virions preserved epitopes of TS and envelope-dimer-epitope CR mAbs and had similar sensitivity to CR polyclonal responses as parental strains. Primary sera from natural infection and human challenge target a region centered on EDIII and secondarily target EDII and EDI. Sera from natural infection had a unique neutralization pattern compared to sera from human challenge, which included greater frequency and higher titer of responses against DENV EDII. In summary, DENV4/2 E recombinant viruses delineate the subdomain targets of TS antibodies after vaccination and primary infection, which may provide new correlates of protection or identify epitopes of neutralizing monoclonal antibodies. IMPORTANCE The four dengue virus (DENV) serotypes infect several hundred million people each year. Although primary infection is generally mild, subsequent infection by differing serotypes increases the risk for symptomatic disease ranging from fever to life-threatening shock. Despite the availability of licensed vaccines, a comprehensive understanding of antibodies that target the viral envelope protein and protect from infection remains incomplete. In this manuscript, we develop a panel of recombinant viruses that graft each envelope domain of DENV2 onto the DENV4 envelope glycoprotein, revealing protein interactions important for virus viability. Furthermore, we map neutralizing antibody responses after primary DENV2 natural infection and a human challenge model to distinct domains on the viral envelope protein. The panel of recombinant viruses provides a new tool for dissecting the E domain-specific targeting of protective antibody responses, informing future DENV vaccine design