Dr. Ann Hessell is a Professor at Oregon Health & Science University and a faculty member within the Pathobiology Division at the Oregon National Primate Research Center. She holds joint appointments within the Divisions of Reproductive and Developmental Sciences and the Vaccine & Gene Therapy Institute. She earned a B.S. in Molecular Biology at the University of California, San Diego and a Ph.D. at Utrecht University in the Netherlands. Before coming to OHSU in 2010, Dr. Hessell trained at The Scripps Research Institute in La Jolla, CA. At Scripps, she studied broadly neutralizing antibodies (bNAbs) 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 bNAbs, 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 she has led several studies using active and passive immunization in NHP models, including using NAbs as immunotherapy in an infant macaque model of mother-to-child transmission (MTCT) of HIV. The work pioneered the finding that bNAbs, 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. 

HIV vaccine development is a core theme of Dr. Hessell’s research. NAbs that develop in HIV infection target the surface glycoprotein coating the virus surface, termed Envelope (Env), the primary focus of vaccine discovery efforts. 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. 

Dr. Hessell’s OHSU 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. Most anti-viral vaccines induce B cell responses (antibodies) to provide protection against infection and disease. 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.