Release of toxic microvesicles by Actinobacillus actinomycetemcomitans

Area of Science:

• Microbiology
• Oral Biology
• Pathogenesis

Background:

• Actinobacillus actinomycetemcomitans (strain Y4) is an oral bacterium.
• This bacterium releases numerous spherical microvesicles during growth.

Purpose of the Study:

• To investigate the biological activities of microvesicles released by Actinobacillus actinomycetemcomitans strain Y4.
• To determine the potential role of these microvesicles in periodontal disease pathogenesis.

Main Methods:

• Analysis of microvesicle composition, including endotoxin content.
• Assessment of biological activities such as chicken embryo lethality and bone-resorbing activity.
• Evaluation of heat stability and proteolysis sensitivity of microvesicle components.

Main Results:

• Microvesicles contained approximately 10% heat- and proteolysis-resistant endotoxin.
• Microvesicle-induced chicken embryo lethality and bone resorption were heat-stable but sensitive to proteolysis.
• Potential presence of heat- and proteolysis-sensitive leukotoxin in microvesicles.

Conclusions:

• Microvesicles from strain Y4 possess potent toxic and bone-resorbing activities.
• These microvesicles may contain both endotoxin and other toxic substances.
• Microvesicles are implicated as significant factors in the pathogenesis of periodontal diseases.