 The hypothesis is that the vaccine regimen is safe and induces a neutralizing antibody response to CHIKV. The primary objectives are to evaluate safety and tolerability of a 2-injection investigational vaccine regimen of VRC-CHKVLP059-00-VP at 20 mcg compared to placebo PBS in healthy adults in CHIKV endemic areas. The secondary objective is to evaluate neutralizing antibody response in vaccine recipients. The exploratory objectives relate to assessing incidence of CHIKV infection in vaccine and placebo recipients, as well as antigen-specific humoral and cellular immune responses during the study. 