Ann J. Hessell PhD

Oregon Health & Science University

Dr. Ann Hessell, PhD, is a Research Assistant Professor at Oregon Health & Science University and an adjunct faculty member of the Vaccine & Gene Therapy Institute within the Pathobiology and Immunology Division at the Oregon National Primate Research Center. She earned a BS in Molecular Biology at the University of California, San Diego and a PhD at Utrecht University in the Netherlands. Her early research training was done at The Scripps Research Institute where she studied broadly neutralizing antibodies (NAbs) isolated from natural HIV infection and led several studies in nonhuman primates (NHP) that have contributed crucial information in defining antibody protection. Based on this work, she published a series of papers demonstrating that NAbs, if present before virus exposure, can block infection. One of these publications is considered seminal in the field, confirming that Fc receptor binding of antibodies is a requirement for optimal protection against HIV infection.

At OHSU, Ann has continued her interest in antibody-mediated protection from HIV infection and, most recently, she has led a study using NAbs as immunotherapy in an infant macaque model of mother-to-child transmission (MTCT) of HIV. The study pioneered the finding that NAbs, when present during early infection, can clear infected cells from tissues harboring active virus, a significant advancement in understanding HIV immunobiology. This study and subsequent ongoing experiments are expanding the awareness of the potential for antibody interruption of virus seeding before latent reservoirs can be established and represent important strides towards a full understanding of the mechanism of antibody-mediated protection and the beneficial roles for NAbs beyond direct protection. The complete potential of antibodies against HIV-1 in clinical applications remains to be revealed, and her interests are focused on examining the full contribution of NAbs in reducing the risk of infection, controlling virus load, and in influencing the development of effective adaptive immune responses by vaccination and immunotherapy.

HIV vaccine development is the core theme of Dr. Hessell’s research. She has led several vaccine studies while at OHSU that are based on using natural Env as an immunogen to understand the dynamics of NAb development in NHP models. These studies have led to new investigations of the immune repertoire of vaccinated macaques using single B-cell sorting techniques and subsequent cloning of monoclonal antibodies for further characterization. By examining populations of memory B cells in vaccinated macaques, Dr. Hessell’s laboratory seeks to identify individual Env-specific B cells and to uncover antibody specificities elicited by immunization that may provide signatures of a protective antibody response elicited by a given vaccine candidate.