Rational immunogen design aims to focus antibody responses to vulnerable antigenic sites on the surface of viruses by engineering protein subunit vaccines. Given the size of these viral antigens there is however potential for eliciting unwanted, off-target responses that compete with more desirable epitopes. My lab use cryoEM and a variety of other assays to provide atomic level information for guiding rational immunogen design and structurally characterizing immune responses to these experimental vaccines in animals. Our pipeline approach drives the iterative improvement of these subunit vaccines and we are currently conducting a variety of studies to focus immune responses on key epitopes on the HIV envelope glycoprotein.