Chlamydia trachomatis infections represent a critical unmet medical need. Chlamydia trachomatis is an obligate intracellular pathogen that can cause blinding trachoma, urethritis, cervicitis and salpingitis, and is an important cofactor for transmission of human immunodeficiency virus. Infection rates associated with this pathogen make it the number one sexually transmitted disease (STD) worldwide. Previous vaccination efforts have been unsuccessful, leading to the suggestion that induction of both a humoral and cellular immune response may be required for protection from infection. Recent studies have led to the identification of specific antigenic epitopes of this pathogen that may provide a potent and durable immunity capable of preventing or reducing rates of infection, and/or clearing an infection. A unique method of delivering such antigens across intact mucosal epithelia using a non-toxic form of Pseudomonas aeruginosa exotoxin A (ntPE) has also recently been identified. This Phase I application proposes the development and pre-clinical testing of several potential vaccines composed of ntPE chimeras that contain a variety of these specific C. trachomatis antigens integrated into specific sites of the carrier. The goal of these studies is to identify a viable vaccine candidate for clinical development in the prevention of the STD associated with C. trachomatis infection.