Yewann Leong

Dr. Leong’s research career began at Australia’s University of Adelaide, where he earned his bachelor’s degree in biotechnology in 2006 and an honor’s degree in 2007. He then joined Monash University as an immunology research assistant, serving this role for one year before beginning his pursuit of a Ph.D. in biomedical science. He earned his PhD degree from Monash in 2016 and remained there to conduct immunology research for another year. In 2017, he took up a research position at the University of California, San Francisco (UCSF). He continues to work at UCSF, focusing on immune responses to infectious diseases as well as autoimmune responses.

Dr. Leong’s contributions to the field are best summarized by describing one of the research projects that he has conducted. In this project, Dr. Leong researched methods of targeting viruses that frequently eluded standard immune responses. The most common and dangerous examples of these viruses are the human immunodeficiency virus (HIV) and Epstein-Barr virus (EBV). As with most viruses, the immune system sends T-cells to target them. The body forms antigen-specific CD8+ T-cells, some of which develop into effector cytotoxic T-cells. These cells are designed to attack not only specific types of viruses, but the cells that the viruses have infected to ensure they are eradicated. However, when HIV or EBV infections are attacked, some specimens of the viruses relocate to regions of the body where T-cells do not patrol as frequently. In particular, they take refuge within B-cell follicles and associated helper cells, where they have the opportunity to replicate and spread before they are detected again. Dr. Leong thoroughly studied both B-cell follicles and the T-cell development process, searching for factors that drew T-cells to B-cell follicles. He was aware that T-cell positioning was determined by the actions of molecules such as integrins and chemokine receptors. In particular, the chemokine receptor known as CXCR5 was known to be responsible for T-cells’ migration to B-cell follicles. Researching CXCR5 revealed an associated type of cytotoxic T-cell that he observed traveling to B-cell follicles. He named it the follicular cytotoxic T-cell and learned that it had a development cycle distinct from other cytotoxic T-cells. Using transcriptional profiling and phenotyping, he identified genes that influenced follicular cytotoxic T-cells. Given the information that Dr. Leong obtained about T cells, his research is important to the development of more advanced antiviral treatments.