The long-term goal of this project is to develop a highly active tetravalent vaccine to prevent Dengue Virus (DENV) infection using a novel vaccine delivery nanoparticle (PRINT-NP) platform with novel PAMP-based adjuvants. DENV infection has posed a serious global public health problem. No DENV vaccines are currently available, partly due to the lack of efficient vaccine delivery/adjuvants and of robust in vivo models of human vaccine responses and DENVl-4 infection. Due to the significant difference between mouse and human immune systems, humanized mice will play a critical role in evaluating human adjuvants, novel antigens and vaccine delivery platforms. Recent improved humanized mouse models have allowed stable reconstitution of a functional human immune system that have been increasingly used for evaluating and comparing human immune response to vaccination and to DENV infection. The AFC8-hu HSC/Hep/TEC mouse developed in the Su group with both human immune and liver cells is well-suited for evaluating human adjuvants and DENV vaccines and for studying DENV infection. With a stable human immune system from human HSC/TEC transplant, functional human immune cells are developed in all lymphoid/liver organs in AFC8-hu mice, which will provide an improved humanized mouse model for evaluating human vaccine response and DENV infection. Using humanized mouse models, we will model and develop novel PRINT-NP to deliver novel vaccine/adjuvant to human APC that induce efficient human protective immunity in vivo. Thus findings from this project will help to 1) identify top PRINT-NP for delivering human vaccines to induce human immunity; 2) develop novel PAMP-based human adjuvants; 3) define novel DENV antigens to induce neutralizing antibody (nAb); 4) establish the humanized mouse model for studying DENV1-4 infection and evaluating DENV vaccines; and 5) identify top tetravalent DENV vaccines for further clinical development. The PRINT-NP and novel adjuvants platform can also be used in vaccine design against other emerging pathogens.