EXCEED THE SPACE PROVIDED. Nontypable Haemophilus influenzae is a common cause of localized respiratory tract disease, including otitis media, sinusitis, bronchitis, and pneumonia. In addition, this organism causes serious systemic disease, such as meningitis, endocarditis, and septicemia. The initial step in the pathogenesis of nontypable H. influenzae disease involves colonization of the upper respiratory mucosa. We have identified an H. influenzae serine protease called Hap, which facilitates intimate interaction with epithelial cells and extracellular matrix proteins and also promotes bacterial aggregation and microcolony formation. Based on our in vitro results, we speculate that Hap plays an important role in the process of colonization. Hap belongs to the growing family of autotransporter proteins and is synthesized as a precursor protein with 3 functional domains, including an N-terminal signal sequence, an internal protease domain with adhesive activity (Haps), and a C-terminal outer membrane domain with translocator activity (HapB). Ultimately, Hap undergoes autoproteolytic cleavage, with extracellular release of Haps. In recent wor k, we demonstrated that Hap- mediated adherence and microcolony formation are potentiated by a host protein called secretory leukocyte protease inhibitor (SLPI). This protein is present in respiratory secretions and inhibits Hap autoproteolysis, resulting in accumulation of surface-associated Haps. In the present proposal, we will focus on Hap-mediated adherence and microcolony formation.
In Aim 1, we will solve the crystal structure of Haps and define the interactive surfaces involved in adherence and microcolony formation.
In Aim 2, we will examine the ability of microcolonies to resist killing by cationic peptides, to evade macrophage phagocytosis, and to enhance persistence in the chinchilla otitis media model.
In Aim 3, we will characterize the relationship between respiratory viral infection and Hap-mediated adherence and microcolony formation, concentrating on the role of SLPI. From a practical perspective, the proposed studies may facilitate efforts to develop novel strategies for the treatment and prevention of H. influenzae disease. Perhaps more importantly, they may provide general insights into host-microbe relationships and expand our understanding of microbial biofilms. PERFORMANCE SITE ========================================Section End===========================================
|Spahich, Nicole A; Hood, Derek W; Moxon, E Richard et al. (2012) Inactivation of Haemophilus influenzae lipopolysaccharide biosynthesis genes interferes with outer membrane localization of the hap autotransporter. J Bacteriol 194:1815-22|
|Meng, Guoyu; Spahich, Nicole; Kenjale, Roma et al. (2011) Crystal structure of the Haemophilus influenzae Hap adhesin reveals an intercellular oligomerization mechanism for bacterial aggregation. EMBO J 30:3864-74|
|Sukupolvi-Petty, Soila; Grass, Susan; St Geme 3rd, Joseph W (2006) The Haemophilus influenzae Type b hcsA and hcsB gene products facilitate transport of capsular polysaccharide across the outer membrane and are essential for virulence. J Bacteriol 188:3870-7|
|O'Neill, Joshua M; St Geme 3rd, Joseph W; Cutter, David et al. (2003) Invasive disease due to nontypeable Haemophilus influenzae among children in Arkansas. J Clin Microbiol 41:3064-9|