Short Report: Antigenic Relationships between Sylvatic and Endemic Dengue Viruses

Abstract. Sylvatic dengue viruses (DENVs) are transmitted between non-human primates and arboreal Aedes spp. mosquitoes in Southeast Asia and west Africa. Recent evidence suggests that the risk for re-emergence of sylvatic DENV into the urban endemic/epidemic cycle may be high, which could limit the potential for eradicating the human transmission cycle with vaccines now under development. We assessed the likelihood of sylvatic DENV re-emergence in the face of immunity to current endemic strains or vaccines by evaluating the neutralization capacity of sera from DENV vaccinees and convalescent patients after primary infection with DENV-2 and DENV-3 serotypes. Our data indicate robust homotypic cross-immunity between human sera and sylvatic DENV strains, but limited heterotypic neutralization. Should a licensed vaccine lead to the eradication of the urban transmission cycle in the future, re-emergence of sylvatic strains into the urban cycle would be limited by homotypic immunity mediated by virus-neutralizing antibodies. Sylvatic dengue viruses (DENVs) are both ecologically and evolutionary distinct from urban DENVs and are transmitted in an enzootic cycle most likely between non-human primates and arboreal Aedes spp. mosquitoes. In Southeast Asia, iso-lations of zoonotic DENV-1, DENV-2, and DENV-4 sugges