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Preliminary characterization of chemically generated Mycobacterium avium subsp. paratuberculosis cell wall deficient
Murray E Hines1, Eloise L Styer
1Tifton Veterinary Diagnostic and Investigational Laboratory, College of Veterinary Medicine, University of Georgia, P.O. Box 1389, 43 Brighton Road, Tifton, GA 31793, USA. mhines@tifton.uga.edu
Veterinary Microbiology
|August 26, 2003
Summary
Cell wall deficient (CWD) forms of Mycobacterium avium subsp. paratuberculosis (MAP) show distinct morphological and antigenic differences compared to their cell wall competent (CWC) counterparts, potentially impacting Crohn's disease and Johne's disease pathogenesis.
Area of Science:
- Microbiology
- Immunology
- Veterinary Medicine
Background:
- Cell wall deficient (CWD) forms of Mycobacterium avium subsp. paratuberculosis (MAP), genetically identical to standard strains, have been found in Crohn's disease and sarcoidosis patients.
- These MAP CWD forms may play a role in the development of Crohn's disease, sarcoidosis, and Johne's disease in animals.
- Isolating and studying MAP CWD forms is challenging due to their tendency to revert to cell wall competent (CWC) forms in vitro.
Purpose of the Study:
- To compare the morphological, chemical, and antigenic characteristics of MAP CWD forms with their CWC counterparts.
- To investigate the potential role of MAP CWD in the pathogenesis of Johne's disease and related human inflammatory conditions.
Main Methods:
- Chemically induced CWD forms of MAP strain 19698 were generated.
- Comparative analysis using electron microscopy, chemotype profiling (MSP-TD, TLC), SDS-PAGE, and Western blotting.
- Antigen recognition by sera from Johne's disease positive and negative cattle was assessed.
Main Results:
- Electron microscopy revealed CWD forms were larger, rounder, and lacked most of their cell walls, being membrane-bound.
- Chemotype profiles and SDS-PAGE showed significant differences, including the loss or reduction of lipoarabinomannan (LAM) and phosphatidylinositol mannosides (PIM) in CWD forms.
- Western blots indicated altered antigenicity in CWD forms, with reduced signal for LAM and other constituents, and differential recognition by cattle sera.
Conclusions:
- MAP CWD and CWC forms exhibit marked differences in morphology, cell wall composition, and antigenicity.
- These differences suggest a distinct biological state for MAP CWD forms, potentially relevant to disease mechanisms.
- Further research into MAP CWD is warranted to understand their role in Johne's disease and potential links to human inflammatory bowel diseases.