Current approaches to mine functional immune responses are generally limited in quality or throughput. To address these limitations, our group established high-throughput functional screening platforms for natively paired antibodies and T cell receptors generated in vivo. Here we will share several case studies of immune mining and engineering from in vivo leads.

Primary mouse B cells were engineered so their heavy and kappa variable-chain loci were scarlessly overwritten by their respective human antibody variable-chain genes. These B cells proliferated in vivo to generate potent neutralizing plasma, and affinity matured to develop broader, more potent, and more bioavailable HIV-1 and SARS-CoV-2 neutralizing antibodies. This approach improves the clinical utility of antibodies and biologics, enables more human-like vaccine models, and suggests new cell-based therapies.

The rapid evolution of SARS-CoV-2 has resulted in continuous escape from traditional IgG-based monoclonal antibody (mAb) therapeutics, suggesting that new antibody engineering and delivery strategies are required to keep pace with viral evolution. In this presentation, I will describe the discovery and engineering of multi-specific antibodies with broad and potent activity against SARS-CoV-2 variants and the in vivo delivery of these constructs using mRNA technology.

Identifying novel epitopes naturally targeted by the human antibody repertoire is an important component of immunogen design aimed at eliciting protective antibodies to infectious disease. I will describe techniques used to survey and characterize monoclonal antibodies generated in response to experimental vaccines in human clinical trials.

After vaccination, responding B cells may differentiate along the extrafollicular path, which leads to the production of short-lived plasmablasts, or along the germinal center (GC) route, which leads to the generation of long-lived plasma cells and memory B cells. GCs are the primary site of affinity maturation, the process whereby the binding affinity of induced antibodies to vaccine antigens increases with time after vaccination. We have recently shown that mRNA vaccination against SARS-CoV-2 in humans can elicit a GC reaction that engages pre-existing memory B cell clones and de novo ones that can target new epitopes, broadening the spectrum of vaccine-induced protective antibodies. These findings raised the following important questions: (1) What are the dynamics of vaccine-induced GC B cell responses in humans? (2) Do responding GC B cells accumulate somatic hypermutations (SHM) after mRNA vaccination? (3) Can a GC reaction be remounted upon repeat mRNA vaccination? These are some of the questions I will discuss in my presentation.