IAI FigSearch
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Hoppe, H. C.
Right arrow Articles by Ehlers, M. R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Hoppe, H. C.
Right arrow Articles by Ehlers, M. R.

 Previous Article  |  Next Article 

Infect. Immun., Sep 1997, 3896-3905, Vol 65, No. 9
Copyright © 1997, American Society for Microbiology

Identification of phosphatidylinositol mannoside as a mycobacterial adhesin mediating both direct and opsonic binding to nonphagocytic mammalian cells

HC Hoppe, BJ de Wet, C Cywes, M Daffe and MR Ehlers
Department of Medical Biochemistry, University of Cape Town Medical School, South Africa.

The molecular basis for the binding of Mycobacterium tuberculosis to nonphagocytic cells, which are readily infected in vitro, and the in vivo significance of this interaction are incompletely understood. Of six cell types tested, we found that only two, Chinese hamster ovary (CHO) fibroblasts and primary porcine aortic endothelial cells, were able to bind M. tuberculosis H37Rv efficiently in vitro. Binding to both CHO and endothelial cells was markedly (three- to fivefold) enhanced by 10 to 20% human or bovine serum, suggesting that the bacteria were coated by a serum opsonin. Preincubation with individual candidate opsonins revealed that recombinant human mannose-binding protein (rMBP), fibronectin, and transferrin were each able to enhance binding threefold. Preincubation of bacteria in serum depleted of mannan-binding lectins or in genetic MBP-deficient serum resulted in enhancements that were only approximately 60 and 58%, respectively, of that produced by preincubation in control serum. In contrast, serum depleted of fibronectin or transferrin retained its opsonizing capacity, suggesting that the latter two are not significant opsonins in whole serum. Binding of M. tuberculosis and Mycobacterium smegmatis to both CHO and endothelial cells in the presence or absence of serum was blocked (60 to 70%) by a monoclonal antibody, MAb 1D1, selected for recognition of intact bacilli. The 1D1 antigen was purified from mycobacterial cell walls and chemically identified as a polar phosphatidylinositol mannoside (PIM). Latex beads coated with purified 1D1 antigen bound to CHO cells, which was enhanced threefold by serum and abolished by periodate treatment, suggesting a requirement for the PIM mannoses in opsonic adhesion. This was likely mediated, at least in part, by serum MBP, as rMBP bound strongly to 1D1 antigen in both thin- layer chromatography overlay and plate binding assays, the latter in a mannan-inhibitable manner. This is the first demonstration that mycobacterial PIMs can function as adhesins for binding to nonphagocytic cells, both directly and after opsonization with serum proteins, including MBP.


This article has been cited by other articles:




Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. J. Virol. Eukaryot. Cell
Microbiol. Mol. Biol. Rev. Clin. Vaccine Immunol. All ASM Journals

Copyright © 1997 by the American Society for Microbiology. All rights reserved.