The main research area of this laboratory is bacterial pathogenesis and the innate immune system, with a special focus on neonatal systemic infections of group B streptococci. It has been proposed that a certain phylogenetic lineage of serotype III group B streptococci (ST-17 complex or RDP III-3 type) is more likely to be invasive than other lineages. Using a molecular genetic approach, our laboratory seeks to discover and characterize microbial virulence determinants that enable ST-17 complex strains to cause invasive disease in human neonates. We have also investigated the contribution of the lectin pathway of complement and opsonophagocytic killing in neonatal host defense systems against invasive group B streptococcal infection. In collaboration with Professor John Bonsack of the University of Utah, Professor Elisabeth Adderson of St. Jude Children's Research Hospital, Professor Misao Matsushita of Tokai University, and Professor Teizo Fujita of Fukushima Medical University, the laboratory is now trying to clarify the role played by cell surface components and structures in the diversity of L-ficolin binding among different phylogenetic lineages. 
Original, peerreviewed publications. Aoyagi, Y., Adderson, E., Rubens, C., Bohnsack, J., Min, J-G., Matsushita, M., Fujita, T., Okuwaki, Y., and Takahashi, S. 2008. L-ficolin/mannose-binding lectin-associated serine protease complexes bind to group B streptococci primarily through N-acetylneuraminic acid of capsular polysaccharide and activate the complement pathway. Infct. Immun. 76:179-188. Lin, F-Y, Whiting, A., Adderson, E., Takahashi, S., Dunn, D., Weiss, R., Azimi, P., Philips, J 3rd., Weisman, L., Regan, J., Clark, P., Rhoads, G., Frasch, C., Troendle, J., Moyer, P., and Bohnsack, J. 2006. Phylogenetic lineages of invasive and colonizing strains of serotype III group B streptococci from neonates: a multi center prospective study. J. Clin. Microbiol. 44:1257-1261. Aoyagi, Y., Adderson, E., Min, J-G., Matsushita, M., Fujita, T., Takahashi, S., Okuwaki, Y., and Bohnsack, J. 2005. Role of L-ficolin/ mannose-binding lectin-associated serine protease complexes in the opsonophagocytosis of type III group B streptococci. J. Immunol. 174:418-425. |
