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rOmpA is a critical protein for the adhesion of Rickettsia rickettsii to host cells

H Li1, D H Walker

  • 1Department of Pathology, The University of Texas Medical Branch, Galveston, TX, 77555-0609, USA.

Microbial Pathogenesis
|June 13, 1998
PubMed

Insights

The outer membrane protein A (rOmpA) of Rickettsia rickettsii is crucial for host cell adhesion. Blocking rOmpA prevents bacterial attachment, highlighting its role in initiating infection.

Area of Science:

  • Microbiology
  • Cell Biology
  • Infectious Diseases

Background:

  • Rickettsia rickettsii causes Rocky Mountain spotted fever.
  • Surface proteins mediate bacterial adhesion to host cells.
  • rOmpA and rOmpB are key surface proteins of R. rickettsii.

Purpose of the Study:

  • To investigate the role of rOmpA and rOmpB in R. rickettsii host cell adhesion.
  • To identify the specific rickettsial protein responsible for initial attachment.

Main Methods:

  • Monoclonal antibodies targeting rOmpA, rOmpB, and LPS were used to inhibit bacterial attachment.
  • Fab fragments of antibodies were employed to confirm binding specificity.
  • Purified rOmpA was tested for competitive inhibition.
  • Trypsin digestion was used to assess surface protein accessibility and function.

Main Results:

  • Monoclonal antibodies against rOmpA significantly inhibited R. rickettsii attachment to L-929 cells (up to 90%).
  • Antibodies against rOmpB and LPS did not affect bacterial adhesion.
  • Fab fragments confirmed these findings.
  • Purified rOmpA demonstrated competitive inhibition of attachment.
  • Trypsin digestion of rOmpA abolished bacterial adhesion.

Conclusions:

  • rOmpA is essential for the initial adhesion of R. rickettsii to host cells.
  • rOmpB and LPS are not involved in the initial attachment process.
  • rOmpA is a critical factor in Rickettsia rickettsii pathogenesis.

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