BPS2026 – Using genetic expansion and fluorescence microscopy to define host-pathogen interactions

Growing antibiotic resistance has been well established as a pressing global health threat. As the effectiveness of existing antibiotics continues to decline, the development of new drugs has struggled to keep pace with the rapid evolution of bacterial resistance. This widening gap underscores the urgency for alternative therapeutic strategies. One promising direction is the development of drugs that target host-pathogen interactions. However, the success of such an approach depends on achieving a highly specific and mechanistic understanding of these complex interactions. This project focuses on developing whole-cell methods to investigate the attachment invasion locus (Ail) protein and its role in mediating the interactions between human epithelial cells and Yersinia pestis , the bacterium responsible for plague. Ail, an outer membrane protein, plays a central role in both immune evasion and host invasion. Ail binds the human protein Vitronectin, enabling Y. pestis to disguise itself from immune attack while also promoting bacterial adherence to host cells by binding integrin. Despite the importance of this interaction, the precise amino acids mediating Ail-Vitronectin binding remain unidentified. Because Ail is surface-exposed, highly conserved, and essential for virulence, it represents an excellent candidate for chemical biology approaches that can later be extended to homologous proteins in related pathogens. Mapping these molecular interactions could ultimately inspire new antibacterial drug strategies that disable virulence without directly targeting bacterial viability. To accomplish these objectives, this project employs techniques including unnatural amino acid incorporation, bio-orthogonal fluorescent probe labeling, serum resistance assays to confirm Ail’s functional activity, and fluorescence microscopy to visualize Ail-Vitronectin co-localization. Together, these complementary methods will provide critical insights into Ail’s role in pathogenesis and pave the way for novel therapeutic interventions.