A live dengue virus vaccine carrying a chimeric envelope glycoprotein elicits dual DENV2-DENV4 serotype-specific immunity.

The four dengue virus serotypes co-circulate globally and cause significant human disease. Dengue vaccine development is challenging because some virus-specific antibodies are protective, while others are implicated in enhanced viral replication and more severe disease. Current dengue tetravalent vaccines contain four live attenuated serotypes formulated to theoretically induce balanced protective immunity. Among the number of vaccine candidates in clinical trials, only Dengvaxia is licensed for use in DENV seropositive individuals. To simplify live-virus vaccine design, we identify co-evolutionary constraints inherent in flavivirus virion assembly and design chimeric viruses to replace domain II (EDII) of the DENV2 envelope (E) glycoprotein with EDII from DENV4. The chimeric DENV2/4EDII virus replicates efficiently in vitro and in vivo. In male macaques, a single inoculation of DENV2/4EDII induces type-specific neutralizing antibodies to both DENV2 and DENV4, thereby providing a strategy to simplify DENV vaccine design by utilizing a single bivalent E glycoprotein immunogen for two DENV serotypes.