We study human B cells and neutralizing antibody responses against hepatitis C virus (HCV), hepatitis B virus (HBV), SARS-CoV-2, and respiratory syncytial virus (RSV). Our overarching hypothesis is that understanding the B cell response in individuals who naturally control infections, and those who have been vaccinated, can help us to understand the basic biology behind successful immune responses, leading to design of more effective vaccines. A particular technical strength of our laboratory is high dimensional flow cytometric analysis of antigen-specific B cells, which allows us to phenotype these rare cells, and also to sequence B cell receptor (BCR) repertoires and isolate virus-neutralizing monoclonal antibodies (mAbs).