Adderson: Characterization of novel virulence factors for encapsulated bacterial pathogens

Our laboratory is focused on the identification of virulence factors of two important pathogens of infants, Group B Streptococcus agalactiae (GBS) and Haemophilus influenzae. GBS are the most common cause of serious bacterial infections in neonates and an important pathogen in pregnant women and adults with underlying medical problems. Despite the frequency and severity of these infections, our understanding of their pathogenesis is incomplete. We have used a novel classification system to identify genetically-related strains of serotype III GBS that cause the majority of neonatal infections. We hypothesize that these strains contain virulence genes that are absent in less virulent stains. Using subtractive hybridization, we have identified regions of genomic DNA that are unique to pathogenic strains of GBS. Among potential virulence genes contained in these regions are several genes that are important in adhesion to and invasion of epithelial tissues, the initial steps required for GBS infection. Our laboratory is currently characterizing these and other potential virulence factors.

Serotype b H. influenzae was the leading cause of serious infections in infants prior to the development of a highly effective vaccine in the 1980's. Infections due to other H. influenzae serotypes are very uncommon, however we recently noted an outbreak of serious disease to serotypes a and e in the Intermountain West. Affected children had normal immunological evaluations, therefore we hypothesize bacterial factors contribute to the increased virulence of these bacteria. Our laboratory is currently identifying these factors and the genetic mechanisms by which respiratory pathogens may acquire virulence genes.

 

Last update: April 2003