Efficacy of a tetravalent chimeric dengue vaccine (DENVax) in Cynomolgus macaques.

Three tetravalent formulations of chimeric dengue (DENVax) viruses containing the pre-membrane and envelope genes of serotypes 1–4 expressed by the attenuated DENV-2 PDK-53 genome were tested for safety, immunogenicity, and efficacy in cynomolgus macaques (Macaca fascicularis). Subcutaneous injection of the DENVax formulations was well-tolerated. Low levels of viremia of only one of the four vaccine viruses were detected yet virus neutralizing antibody titers were induced against all four dengue virus serotypes after one or two administrations of vaccine. All animals immunized with the high-dose formulation were protected from viremia, and all immunized animals were completely protected from DENV-3 and DENV-4 challenge. A lower dose of DENVax formulation partially protected animals from DENV-1 or DENV-2 challenge. In contrast, all control animals developed high levels of viremia for multiple days after challenge with DENV 1–4. This study highlights the immunogenicity and efficacy of the tetravalent DENVax formulations in nonhuman primates.