Short report: Antigenic relationships between sylvatic and endemic dengue viruses

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, reemergence of sylvatic strains into the urban cycle would be limited by homotypic immunity mediated by virus-neutralizing antibodies.