Group B streptococcal infections in the postgenomic era

Dr Rubens is a pediatric infectious disease specialist and microbiologist, with a longstanding interest in the molecular pathogenesis of bacterial perinatal infections by Gram-positive bacteria. Group B streptococci (GBS) have been shown to invade eukaryotic cells and this process may be the main mechanism used by the organism to cause disease in neonates. Molecular approaches are used to identify the genetic and biochemical basis of specific virulence traits, such as epithelial/endothelial cell entry and transcytosis, evasion of innate immune mechanisms by inhibiting complement activation and phagocytic uptake, and microbial survival in various host environments (bloodstream, reproductive system and neonatal lung). Hence, these projects apply to both in vitro and in vivo model systems. Genetic techniques are also utilized to identify the genes and biosynthetic mechanisms important for the production of capsular polysaccharide and other virulence traits by GBS. Recently, Dr Rubens's group has started a project characterizing the early stages of bacterial pneumonia by investigating the host:pathogen interaction after introducing Staphylococcus aureus into the airway using genomic and proteomic techniques. This project will eventually characterize the bacterial response to the lung airway, including specific traits critical for microbial persistence in the face of lung innate immunity. They have also begun to characterize the host airway proteome for the proteins that contribute to innate immune mechanisms.