PROJECT 2: ABSTRACT Project 2 is a contraceptive translational research project designed to support the overall mission of our CRC program which is to develop a new contraceptive method based on the vaginal use of a potent sperm agglutinating antibody, Human Contraceptive Antibody (HCA). Preclinical studies will be performed to establish the potency, specificity, safety and mechanism of action of the GMP HCA antibody manufactured for the HCA-film clinical trial. We will also support the Phase 1 clinical trials by testing vaginal secretions from women before and after HCA-film use for proinflammatory cytokines and antisperm antibodies. In addition, we will determine the PK/PD of a prototype HCA intravaginal ring (IVR) and HCA antibody distribution in a nonhuman primate model, and will engineer novel multivalent HCA constructs that are designed for enhanced sperm agglutination activity and may be used for second generation HCA contraceptive products. Our specific aims are: SA1: Test GMP HCA in in vitro assays of human sperm function to determine concentration(s), duration, and mechanism(s) of action of HCA contraceptive effects. SA2: Test specificity and safety of GMP HCA and HCA-film in vitro. SA3: HCA-IVR PK/PD and imaging of HCA and sperm distribution in NHP model. SA4: Test vaginal secretions from women in clinical trials for cytokines and HCA antisperm activity. SA5: Manufacture HCA multivalent variants engineered for enhanced activity (2nd generation HCA); test in sperm function and safety assays.