Virulence factors of the periodontopathogen Actinobacillus actinomycetemcomitans
The purpose of this article was to review the virulence factors of Actinobacillus actinomycetemcomitans (A.a.). This capnophilic coccobacillus has numerous virulence factors, including bacteriocin, chemotactic inhibition, immunosuppressive factors, cytotoxic factors, iron binding proteins, lipopolysaccharide, collagenases, antibiotic resistance, adhesion to KP epithelial cells, and ability to penetrate epithelial cells.
Adhesion to epithelial cells involves multiple factors including vesicles released by the bacteria and host environmental conditions. Invasion of the host cell occurs within 15 minutes postinfection. The presence of polymerized host cell actin associated with A.a. then can be identified on the indentations of the cell surface as well as in the membrane ruffles where it appears to enter the cell. A.a. does not increase in quantity once in the host cell. It is found free in the cytoplasm shortly after infection. A.a. can tracytose between epithelial cells and is released from the host cell within five hours. The authors hypothesize that A.a. uses invasion of the epithelial cells as a mechanism to penetrate deeper tissues by cell-to-cell spread.
The authors conclude that further studies are required in the development of future prophylactic reagents. [I.S.]
Fives-Taylor, P., D. Meyer, and K. Mintz, J Periodont, 67:291,1996