People

Josiah Gerdts M.D. Ph.D.

Josiah Gerdts, MD, PhD is an autoimmune neurologist in the Department of Neurology at UCSF. His research focuses on engineering synthetic tools to trace intercellular communication in the immune system, with a particular emphasis on T cell antigen discovery to advance diagnostics and treatments for autoimmune neurologic disorders. He is driven by a passion for assay building, high-throughput discovery, and solving hard problems with brute-force molecular biology, cell engineering, and protein engineering.

Josiah grew up in the Midwest and completed his MD and PhD at Washington University in St. Louis in the laboratory of Jeff Milbrandt, where he discovered fundamental regulatory steps in programmed axon destruction, including the finding that the protein SARM1 triggers catalytic NAD+ breakdown in injured axons. This work identified an essential and pharmacologically targetable step in axon degeneration and illuminated an evolutionarily ancient innate immune damage response mechanism. He completed Neurology residency and a fellowship in Autoimmune Neurology at UCSF, supported by an NIH R25 fellowship. As a postdoctoral fellow in Wendell Lim’s lab at UCSF, Josiah developed a new synthetic biology approach for multiplexed discovery of T cell antigen targets. He now combines his expertise in autoimmune neurology and synthetic biology to discover and characterize autoantigens driving autoimmune neurologic disorders and to advance engineered cell therapy technologies for neurologic disease. The lab is supported by the National MS Society, an NIAID K08, and the UCSF Physician-Scientist Scholars Program.

Outside the lab, Josiah is a father of three and enjoys attending his kids' baseball games. He also plays guitar with the San Francisco band Dopamine Drive.

Annabel (Shini) Chen

Annabel (Shini) Chen is an Assistant Specialist in the lab, where she works on antigen discovery for autoimmune diseases using a combination of molecular cloning, T cell engineering, and functional screening approaches. Her current work focuses on identifying and validating antigen-TCR interactions to better understand immune recognition and specificity in autoimmune disease contexts.

She previously earned her M.Sc. in Biomedical Informatics from New York University, where she applied computational methods to study copy number variation and immune evasion across tumor types. She completed her Honors B.Sc. in Microbiology and Immunology at the University of British Columbia, where her thesis focused on the regulation of CD44–hyaluronan interactions in breast cancer metastasis. During this work, she conducted genome-wide CRISPR/Cas9 functional screens to identify regulators of cell surface ligand expression relevant to cancer progression and validated candidate regulators using molecular and cell-based assays, including sequencing, flow cytometry, and confocal microscopy.

Outside the lab, Annabel enjoys exploring the city’s neighborhoods and restaurants, spending time in nature, attending musicals and art galleries, and cooking.

Mahiya Ahmed

Mahiya is an Assistant Specialist in the Gerdts Lab, working on autoimmune antigen discovery. She completed her bachelor's and first master's in Biochemistry and Molecular Biology at the University of Dhaka in Bangladesh, before moving to Europe for the Erasmus Mundus Joint Master's program in Sustainable Drug Discovery (S-DISCO) spanning Belgium, Poland, and the Netherlands. Drawn by UCSF's reputation in drug discovery research, she completed her master's thesis at the Small Molecule Discovery Center (SMDC) under the supervision of Dr. Michelle Arkin.

Her exposure to biochemistry, molecular biology, and drug discovery research sparked a growing interest in immunology, leading to her pivot toward autoimmunity and cell biology.

Outside the lab, she enjoys exploring cozy cafes, reading books, cooking with Bangladeshi flavors, and photographing everyday moments.

Wonyoung Jo

Wonyoung Jo is a PhD student in the UC Berkeley–UCSF Joint Bioengineering Program, co-mentored by Josiah Gerdts and Wendell Lim. His research focuses on developing synthetic biology and T cell engineering approaches for antigen discovery in autoimmune diseases. In the Gerdts Lab, he uses engineered antigen-presenting platforms, patient-derived TCRs, and functional screening approaches to identify disease-relevant antigen–TCR interactions and better understand immune recognition in autoimmune disease contexts.

Wonyoung earned his MSE in Biomedical Engineering from Johns Hopkins University, where he worked in the laboratories of Daniela Čiháková and Taekjip Ha. In Daniela Čiháková’s lab, he studied immune mechanisms of viral, autoimmune, and immune checkpoint inhibitor-associated myocarditis, with a focus on engineered regulatory T cell therapies, inflammatory cardiac fibroblasts, and antigen-specific immune responses in cardiac inflammation. In Taekjip Ha’s lab, he contributed to the development of helicase-mediated isothermal amplification methods for the reliable amplification of repetitive and low-complexity DNA sequences. He completed his BS in Bioengineering at Washington State University, where he developed a CRISPR-Cas12a-based diagnostic platform for SARS-CoV-2 detection.

Wonyoung is broadly interested in building technologies that connect mechanistic immunology with therapeutic design. He is particularly motivated by the potential of engineered immune systems to uncover disease-driving antigens and guide the development of more precise treatments for autoimmune and inflammatory diseases.

Outside the lab, Wonyoung enjoys exploring the Bay Area, spending time with friends, and following developments in science, technology, and design.