Abstract: This invention relates to a transgenic animal model for testing immunogenicity and protective efficacy of human vaccines and the method for generating such a multi-transgenic animal. This invention also relates to methods for screening compositions for human vaccine development. More specifically, the present invention relates to a mouse model capable of expressing human leukocyte antigens DR4 and A2, and/or human costimulatory molecules (CD80) which upon infusion of human HLA-matched hematopoietic stem cells develop a functional human immune system able to respond to vaccination with human vaccines. The invention also relates to method of producing human antibodies specific for a desired antigen using the transgenic mouse.