<i>Aggregatibacter (Actinobacillus) actimycetemcomitans</i> leukotoxin and human periodontitis – A historic review with emphasis on JP2

<jats:title>Abstract</jats:title><jats:sec><jats:label /><jats:p><jats:italic>Aggregatibacter (Actinobacillus) actimycetemcomitans (Aa)</jats:italic> is a gram‐negative bacterium that colonizes the human oral cavity and is causative agent for localized aggressive (juvenile) periodontitis (AgP). In the middle of 1990s, a specific JP2 clone of belonging to the cluster of serotype b strains of <jats:italic>Aa</jats:italic> with highly leukotoxicity (leukotoxin, LtxA) able to kill human immune cells was isolated. JP2 clone of <jats:italic>Aa</jats:italic> was strongly associated with in particularly in rapidly progressing forms of aggressive periodontitis. The JP2 clone of <jats:italic>Aa</jats:italic> is transmitted through close contacts. Therefore, AgP patients need intense monitoring of their periodontal status as the risk for developing severely progressing periodontitis lesions are relatively high. Furthermore, timely periodontal treatment, including periodontal surgery supplemented by the use of antibiotics, is warranted. More importantly, periodontal attachment loss should be prevented by early detection of the JP2 clone of <jats:italic>Aa</jats:italic> by microbial diagnosis testing and/or preventive means.</jats:p></jats:sec>