Dr. Youn Soo Choi is a faculty member at Seoul National University with a research focus on immunology, particularly the cellular and molecular mechanisms that govern humoral immune responses and vaccine efficacy.

Dr. Choi earned his Ph.D. in Immunology from the University of California, Davis, where he conducted his doctoral research under the mentorship of Professor Nicole Baumgarth, D.V.M., Ph.D.. His work investigated how innate-like B-1 cells respond to respiratory infection by influenza A virus, contributing to a foundational understanding of early B cell-mediated antiviral immunity.

Following his Ph.D., Dr. Choi pursued postdoctoral training in the laboratory of Professor Shane Crotty, Ph.D., at the La Jolla Institute for Immunology (LJI), a world leader in follicular helper T cell (Tfh) biology and vaccinology. During this time, Dr. Choi made several key contributions to the field, including:

1. Elucidating ICOS-mediated regulation of Tfh cells (Immunity, 2011)
2. Revealing IL-2 signaling as a negative regulator of Tfh cell development (J Exp Med, 2012)
3. Identifying IL-6–STAT1/STAT3-dependent pathways in early Tfh cell formation (J Immunol, 2013)
4. Demonstrating the central role of LEF1/TCF1 transcription factors in Tfh differentiation and humoral immunity (Nat Immunol, 2015)

At Seoul National University, Dr. Choi leads a laboratory dedicated to:
Understanding the dynamic behavior of Tfh cells during germinal center responses
Investigating molecular and cellular mechanisms of Tfh differentiation and function to enhance CD4 T cell-dependent vaccine immunity
Engineering vaccine antigens and adjuvants to promote robust germinal center reactions and high-quality antibody production
Designing strategies to elicit broadly neutralizing antibodies (bnAbs) for protection against influenza viruses, coronaviruses, and other pathogens

In addition, his team has expanded its research to explore how Tfh cells and B cells modulate anti-tumor immunity, particularly through their influence on CD8 T cell responses.

Dr. Choi’s lab combines fundamental immunology with translational research approaches, aiming to contribute to next-generation vaccines and immunotherapies for infectious diseases and cancer.