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Association of a major protein antigen of Mycoplasma arthritidis with virulence

A-H T Tu1, B Clapper, T R Schoeb

  • 1Department of Genetics, KAUL, Room 720, University of Alabama at Birmingham, Birmingham, AL 35294-0024, USA.

Infection and Immunity
|December 25, 2004
PubMed

Insights

Mycoplasma arthritidis virulence is linked to a variable protein (P47/P67). Differences in tandem repeats within this protein influence arthritis disease outcome in animal models.

Area of Science:

  • Microbiology
  • Immunology
  • Molecular Biology

Background:

  • Mycoplasma arthritidis is a pathogen causing polyarthritis in rats and mice.
  • It serves as a model for infectious arthritis and studying autoimmunity mediated by the superantigen MAM.
  • A less virulent mutant strain (158-1) was identified, lacking a major antigen (P47) and possessing a new protein (P67).

Purpose of the Study:

  • To investigate the molecular basis for the reduced virulence of M. arthritidis strain 158-1.
  • To characterize the proteins P47 and P67 and their genetic origin.
  • To determine the relationship between these proteins and disease outcome.

Main Methods:

  • Protein extraction using Triton X-114 and analysis by SDS-PAGE and Coomassie blue staining.
  • Mass spectrometry for protein identification.
  • PCR analysis of genomic DNA.
  • Two-dimensional polyacrylamide gel electrophoresis.

Main Results:

  • Strain 158-1 lacks the 47 kDa protein (P47) and produces an abundant 67 kDa protein (P67).
  • P67 was identified as a lipoprotein encoded by the ORF 619 gene.
  • P47 and P67 are products of the same gene (ORF 619) differing in tandem repeat numbers.
  • No other protein differences were detected between the strains.

Conclusions:

  • The tandem repeat region within the ORF 619 gene product (P47/P67) is crucial for M. arthritidis virulence.
  • Variations in this repeat region likely influence the development of arthritis.

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