The Impact of a Pseudomonas Bacteriophage on Chronic Biofilm Lung Infections in Cystic Fibrosis

Project Summary Pseudomonas aeruginosa (Pa) is the most common cause of chronic lung infections in people with Cystic Fibrosis (pwCF) leading to progressive disease and early mortality. Pa displaces other pulmonary pathogens, including Staphylococcus aureus, resulting in infections that often persist for life despite targeted antibiotic treatment. Understanding how Pa establishes chronic lung infections is essential to identify effective therapeutic interventions that will improve outcomes in pwCF. This proposal will investigate the role of Pf bacteriophage (phage), a virus that infects Pa, in promoting disease pathogenesis by facilitating iron acquisition. Iron is an essential nutrient with decisive effects on Pa growth and virulence. How Pa acquires this essential nutrient during chronic lung infections is unclear. Preliminary studies reveal that Pf phage directly binds and locally sequesters iron, thereby driving Pa bacterial growth. In contrast, Pf inhibits iron-mediate growth of S. aureus. Based on these exciting findings, the candidate hypothesizes that Pf phage functions as a novel mechanism of iron acquisition that promotes Pa pathogenesis and fitness during chronic infections. To test this hypothesis, Aim 1 will investigate the biophysical interactions through which Pf mediates iron sequestration and intracellular uptake. Aim 2 will characterize the role of Pf mediated iron uptake on Pa growth and pathogenesis. Aim 3 will determine the role of Pf phage in selectively driving Pa pathogenesis during co- infection with S. aureus. These aims are designed to be synergistic and complimentary to best provide insight into the role of Pf in promoting Pa pathogenesis. If successful, these studies will offer a potentially novel therapeutic target for the treatment of chronic Pa infections. This research program will help the candidate’s career as an independent physician-scientist investigating host-microbial interactions. The candidate is well suited to accomplish the studies in this proposal with extensive clinical training as an infectious disease physician as well as a PhD in microbiology. He is currently an Instructor of Medicine in the Division of Infectious Diseases and Geographic Medicine at Stanford University, School of Medicine with over 80% of his time dedicated to research. This proposal includes a comprehensive mentorship plan to advance the candidates’ skills and career development. Specifically, under the guidance of his mentor, Dr. Paul Bollyky, and advisory committee, the candidate will advance his training, including techniques in molecular biology, imaging modalities, and disease models. The candidate will also receive lab management training which will include courses to improve scientific writing, managing research budgets and leading a team of students and technical staff. Together, this research proposal and customized career development plan will provide the candidate the foundation necessary to become a successful independent investigator.