Member Spotlight: George Liu

George Liu, MD, PhD, is Professor and Chief of Pediatric Infectious Diseases at the University of California, San Diego (UCSD). Dr. Liu received his MD from UCSD, and his PhD in immunology from the University of Cambridge, United Kingdom. He completed his fellowship in Pediatric Infectious Diseases at UCSD where he studied microbial pathogenesis under Victor Nizet.

In 2006, Dr. Liu joined Cedars-Sinai Medical Center where he established his own research program to study the interaction between Staphylococcus aureus and the host immune system. In 2019, he returned to the division of infectious diseases at UCSD where he continued to study host-S. aureus interaction and vaccines.

Why pediatric ID? I grew up in the Cote D’Ivoire in West Africa. I had malaria 5-10 times during my decade-long stay. Therefore, it made sense for me to study infectious diseases.

Where have you taken your ID focus? With my upbringing, I have always thought that infectious diseases research was an area where I could have the greatest impact. My early research focused on immune evasion mechanisms of bacterial pathogens, which I found to be immensely interesting. More recently, our focus shifted to addressing questions that have more immediate translational relevance.

What is a recent development or achievement in your career? For close to a decade, we have been intrigued by the question – why do we not have a working staph vaccine? Basic researchers have little difficult developing staph vaccines in mice, but none of those taken to trials have worked. We noted that laboratory mice are essentially free from human S. aureus colonization whereas humans are colonized within the first few months of life. Therefore, we tested whether pre-exposure to S. aureus could make staph vaccines ineffective. Indeed, that was what we saw.

Naïve mice given the staph IsdB vaccine were protected from S. aureus infection. Mice pre-exposed to S. aureus, then given the same vaccine, were not. We showed that infection with S. aureus led to the generation of abundant non-protective antibodies. Vaccination of mice after S. aureus exposure led to preferential recall of the non-protective memory response. The non-protective antibodies further competed against protective IsdB antibodies to abolish vaccine efficacy. In sum, the recall of non-protective imprints, what has been termed “original antigenic sin,” doomed the IsdB vaccine in the experimental setting.

(Read more in an article co-authored by Dr. Liu, ‘Non-protective immune imprint underlies failure of Staphylococcus aureus IsdB vaccine’)

What do you enjoy most about being a PIDS member; what keeps you renewing your membership? PIDS is incredibly important for our field. We are at an important juncture with the recent waves of epidemics and SARS-Cov-2 pandemic. In the past decade, we have also witnessed many prominent pediatric infectious diseases clinician educators and scientists retire. But we have great difficulty attracting new trainees to our field. Hence, the challenge we are facing is almost “existential.” PIDS can have that leading role that brings all of us together to solve this great challenge. That’s why PIDS membership is so essential.