Recent immunological studies have shown the human anti-DENV immune response to be dominated by prM-specific antibodies in both primary and secondary infections [9, 10] . These prM-specific antibodies are highly cross-reactive and non-neutralizing. When complexed with immature DENV (imDENV), it has the ability to render normally non-infectious imDENV highly infectious [11, 12] . This has caused concern over current vaccine candidates that contain native dengue prM [9] -which is a component of most current vaccine strategies whether naturally attenuated, recombinantly attenuated, yellow fever-dengue-virus chimeras, chemically inacti-vated virus, DNA vaccine or recombinant subunit protein vaccines [13, 14] . Vaccine candidates that do not contain prM proteins, such as soluble recombinant Envelope (E) protein or E domain subunit vaccines may thus become increasingly important.