St. Geme Laboratory

The research focus of the St. Geme laboratory is bacterial pathogenesis, with particular emphasis on gram-negative bacteria that transition from a state of commensalism in the upper respiratory tract to either localized or invasive disease. The lab has concentrated on H. influenzae and K. kingae as model pathobionts and is using genetic methods, protein chemistry, carbohydrate chemistry, X-ray crystallography, high-resolution microscopy, cell biology approaches, and animal models to study the molecular and cellular determinants of H. influenzae and K. kingae disease. H. influenzae is a common cause of respiratory tract disease, sepsis, and meningitis, and K. kingae appears to be the most common etiology of osteomyelitis and septic arthritis in young children and is an important cause of endocarditis. The long-term goals of the lab are to identify candidate vaccine antigens and to elucidate common mechanisms in bacterial pathogenesis that will serve as targets for new antimicrobials with activity against of a wide range of pathogenic gram-negative bacteria.

Project Highlights

• Haemophilus influenzae pathogenicity – understanding the roles of the HMW1/HMW2 adhesins, the Hia/Hsf adhesins, and the Hap adhesin
• Haemophilus influenzae vaccine development – examining the vaccine potential of the HMW1/HMW2, Hia/Hsf, and Hap proteins
• Bacterial protein secretion – characterizing type V secretion, including secretion of two-partner secretion proteins, conventional autotransporters, and trimeric autotransporters
• Kingella kingae pathogenicity – understanding the interrelationship of type IV pili, the Knh autotransporter, and the polysaccharide capsule and the virulence functions of the polysaccharide capsule, the exopolysaccharide, and the RTX toxin
• Relationship between Haemophilus influenzae colonization and asthma – understanding the mechanism of early colonization with H. influenzae in the pathogenesis of asthma