The Haemophilus influenzae Hap serine protease promotes adherence and microcolony formation, potentiated by a soluble host protein

David R. Hendrixson, Joseph W. St. Geme

Research output: Contribution to journalArticle

89 Scopus citations


Haemophilus influenzae initiates infection by colonizing the upper respiratory mucosa. The process of colonization involves adherence to epithelium and evasion of host immunity. In this study, we examined the H. influenzae Hap adhesin, which has serine protease activity and undergoes autoproteolytic cleavage and extracellular release in broth. We found that the uncleaved cell-associated form of Hap mediates adherence to cultured epithelial cells and promotes bacterial aggregation and microcolony formation. Adherence and aggregation are augmented by secretory leukocyte protease inhibitor, a natural component of respiratory secretions that inhibits Hap autoproteolysis. These observations suggest a novel paradigm in hostpathogen relations, in which a soluble host protein whose primary function is to protect host epithelium potentiates properties that facilitate bacterial colonization.

Original languageEnglish (US)
Pages (from-to)841-850
Number of pages10
JournalMolecular cell
Issue number6
StatePublished - Dec 1998


ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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