Annual and Interim Progress Report Summaries
Principal Investigator: Margaret Ackerman/Galit Alter
Project: Leveraging Antibody Effector Function
Submitted August 30, 2012
The goal of the Ackerman/Alter CAVD is to define, induce, and evaluate protection afforded by potent innate immune-recruiting antibodies. Critical to the success of this project is: (a) the development of robust, high-throughput array technology that can predict the Fc-effector function of both naturally produced antibodies and monoclonal antibodies and (b) the development of a in vitro–screening approach to define the signals on B cells that result in the targeted production of innate immune–recruiting antibodies. We are pleased to report that over the first year of the funding period, Objectives 1 and 3 have generated a remarkable technology that can both predict the functional capacity of a pool of naturally produced oligoclonal antibodies and identify new glycan structures on monoclonal antibodies that specifically recruit phagocytosis (a mechanism of antiviral control that may be preferable in tissues) that can be harnessed in the design of new monoclonal therapeutics to target HIV. Quality control evaluation of the array technology shows robust concordance with traditional ELISA and surface plasmon resonance technology, and this technology has been applied to a large HIV-, HCV-, influenza-, TB-infected sample sets. Additionally, over the first year, we have had the opportunity to apply the array to samples acquired from the RV144 and VAX003 vaccine trials. Interestingly, the array technology has clearly defined a unique and parallel Fc signature associated with enhanced antiviral antibody activity in infected subjects and vaccinees, identifying specific populations of IgG3 antibodies harboring the most potent innate immune recruiting activity. Current efforts have been invested into expanding the array technology to include more than two dozen different antigenic determinants in order to integrate information related to protective Fc- and Fab-associated features to define the characteristics of protective antibody responses. In parallel, significant progress in the development of an in vitro B cell screening approach to specifically define the signals that result in the durable production of innate immune–recruiting antibody responses has been achieved in Objective 2. Specifically, it is clear that virally derived ligands, specifically TLR 7, 7/8 and 9 agonists, non-specifically drive the transient production of pro-inflammatory antibody glycans by decreasing the expression of major galactose- and sialic acid–adding enzymes. However, co-ligation of the B cell receptor and/or CD4-co-stimulation profoundly reduces fucose addition, resulting in the production of antibodies with significantly increased ADCC-inducing activity. Importantly, preliminary evidence suggests that these changes may be durably programmed via epigenetic modifications. These data provide the first concrete evidence that vaccines may program long-lived innate immune–recruiting antibody activity, and the reagents and technologies generated in Year 1 can now be used to dissect a larger network of adjuvants/cytokines/ immunomodulators in Objective 4 during Year 2. Together, these studies will provide critical new insights into the characteristics of the most potent non-neutralizing antibody responses and the mechanism by which such antibodies may be induced via vaccination to increase vaccine potency.