Understanding of Streptococcus agalactiae virulence and disease mechanisms using comparative genomics and in vivo models
Group B Streptococcus (GBS) is a Gram-positive bacterium and a leading cause of sepsis and meningitis worldwide and is associated with high rates of mortality and morbidity, especially in infants. GBS is a commensal organism found in the intestinal and vaginal flora; however, under certain circumstances, it can spread into the systemic circulation and cause life-threatening invasive disease. In the newborn, the invasion process is believed to primarily occur via vertical transmission from a carrier mother during the delivery process. To date, ten distinct serotypes have been described based on their capsular polysaccharide composition. As is the case for other Gram-positive bacteria, the GBS capsule is a major virulence factor contributing to the evasion of phagocytosis. Other major virulence factors include haemolysin, C5a peptidase and serine protease, but their role in disease causation remains to be determined. Developing murine models of colonisation transmission and invasive disease is very important to understanding the mechanisms of known and unknown virulence factors. In this project, we seek to identify novel virulence regulators that may play a role in the transition of GBS from carriage to invasive disease.