Influence of pili, fibrils, and capsule on in vitro adherence by Haemophilus influenzae type b.


Journal Article

Haemophilus influenzae type b is an encapsulated bacterium that initiates infection by colonizing the upper respiratory epithelium. In vitro studies indicate that H. influenzae type b is capable of expressing two morphologically distinct filamentous adhesive structures, referred to as pili and fibrils, respectively. In this study, we examined adherence to a variety of human epithelial-cell types and demonstrated that pili and fibrils have separate cellular binding specificities. In addition, we found that capsular material inhibits fibril recognition of the host-cell surface. This inhibitory effect was reduced when bacteria were grown to stationary phase, reflecting diminished encapsulation. However, when growth medium was supplemented with Mg2+, stationary-phase organisms were relatively heavily encapsulated and non-adherent. These observations suggest that encapsulation can be modulated in response to growth phase or environmental signals. It is possible that encapsulation is down-modulated early in the infectious process in order to avoid interfering with colonization. In contrast, encapsulation may be up-modulated between hosts and during bacteremia, where it appears to confer a selective advantage. We speculate that this model may also apply to other encapsulated pathogens.

Full Text

Cited Authors

  • St Geme, JW; Cutter, D

Published Date

  • July 1996

Published In

Volume / Issue

  • 21 / 1

Start / End Page

  • 21 - 31

PubMed ID

  • 8843431

Pubmed Central ID

  • 8843431

Electronic International Standard Serial Number (EISSN)

  • 1365-2958

International Standard Serial Number (ISSN)

  • 0950-382X

Digital Object Identifier (DOI)

  • 10.1046/j.1365-2958.1996.6241331.x


  • eng