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Mutants of Actinomyces viscosus T14V lacking type 1, type 2, or both types of fimbriae

J O Cisar1, A E Vatter, W B Clark

  • 1Laboratory of Microbial Ecology, National Institute of Dental Research, Bethesda, Maryland 20892.

Infection and Immunity
|November 1, 1988
PubMed

Insights

Actinomyces viscosus T14V has two fimbrial types involved in adhesion. Type 1 fimbriae mediate hydroxyapatite binding, while type 2 fimbriae are linked to lectin activity and coaggregation with Streptococcus sanguis.

Area of Science:

  • Microbiology
  • Bacterial Adhesion
  • Molecular Biology

Background:

  • Actinomyces viscosus T14V possesses fimbriae, which are hair-like appendages crucial for bacterial adhesion and colonization.
  • Understanding the specific roles of different fimbrial types is essential for elucidating host-microbe interactions.

Purpose of the Study:

  • To characterize the distinct functions of type 1 and type 2 fimbriae in Actinomyces viscosus T14V.
  • To investigate the involvement of these fimbriae in adhesion to hydroxyapatite and coaggregation with other bacteria.

Main Methods:

  • Generation and characterization of fimbria-deficient mutants of Actinomyces viscosus T14V using antibody-based selection.
  • Immunospecific double labeling with iron dextran and ferritin-conjugated antibodies to visualize fimbriae.
  • Assays for bacterial adsorption to saliva-treated hydroxyapatite and coaggregation with Streptococcus sanguis.

Main Results:

  • Mutants lacking type 1 or type 2 fimbriae were successfully isolated, confirming the presence of two distinct fimbrial types.
  • Type 1 fimbriae were essential for strong adsorption to saliva-treated hydroxyapatite.
  • Type 2 fimbriae were associated with the Actinomyces viscosus lectin and mediated lactose-sensitive coaggregation with Streptococcus sanguis.

Conclusions:

  • Actinomyces viscosus T14V expresses two antigenically distinct fimbrial types, type 1 and type 2.
  • Type 1 fimbriae play a primary role in adherence to hydroxyapatite, while type 2 fimbriae are involved in specific coaggregation mechanisms.
  • Both fimbrial types contribute to the aggregation of Actinomyces viscosus T14V in the presence of human saliva.

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