ERVW-1 and measles: Other approaches are chimeric vaccine strains based on the genetic backbones from Sindbis virus or the TC-83 vaccine strain of Venezuelan equine encephalitis virus [8,9], [9], a DNA vaccine based on codon-optimized consensus envelope protein (E1, E2 and E3) sequences [10], a VLP-based vaccine expressing the CHIKV envelope proteins [11], or recombinant measles [12].