This vaccine is based on the production of four chimeric live dengue-yellow fever viruses in which the yellow fever (YF) 17D vaccine sequences encoding the envelope proteins prM and E genes were substituted by the prM and E genes from DV of serotype 1, 2, 3, or 4 in a molecular clone of YF-17D [69]. This evidence concerns the gene ERVW-1 and dengue disease.