Division of Molecular Periodontology, Department of Odontology, Faculty of Medicine, Umeå University, Umeå, Sweden.
PLoS One. 2013 Jun 14;8(6):e65781. doi: 10.1371/journal.pone.0065781. Print 2013.
The cytolethal distending toxin (Cdt) is a highly conserved exotoxin that are produced by a number of Gram negative bacteria, including Aggregatibacter actinomycetemcomitans, and affects mammalian cells by inhibiting cell division and causing apoptosis. A complete cdt-operon is present in the majority of A. actinomycetemcomitans, but the proportion of isolates that lack cdt-encoding genes (A, B and C) varies according to the population studied. The objectives of this study were to examine serotype, Cdt-genotype, and Cdt-activity in isolates of A. actinomycetemcomitans collected from an adolescent West African population and to examine the association between the carrier status of A. actinomycetemcomitans and the progression of attachment loss (AL).
A total of 249 A. actinomycetemcomitans isolates from 200 Ghanaian adolescents were examined for serotype and cdt-genotype by PCR. The activity of the Cdt-toxin was examined by DNA-staining of exposed cultured cells and documented with flow cytometry. The periodontal status of the participants was examined at baseline and at a two-year follow-up.
Presence of all three cdt-encoding genes was detected in 79% of the examined A. actinomycetemcomitans isolates. All these isolates showed a substantial Cdt-activity. The two different cdt-genotypes (with and without presence of all three cdt-encoding genes) showed a serotype-dependent distribution pattern. Presence of A. actinomycetemcomitans was significantly associated with progression of AL (OR = 5.126; 95% CI = [2.994-8.779], p<0.001).
A. actinomycetemcomitans isolated from the Ghanaian adolescents showed a distribution of serotype and cdt-genotype in line with results based on other previously studied populations. Presence of A. actinomycetemcomitans was significantly associated with disease progression, in particular the b serotype, whereas the association with disease progression was not particularly related to cdt-genotype, and Cdt-activity.
细胞致死扩张毒素（Cdt）是一种高度保守的外毒素，由许多革兰氏阴性菌产生，包括伴放线放线杆菌，通过抑制细胞分裂和诱导细胞凋亡来影响哺乳动物细胞。大多数伴放线放线杆菌中存在完整的 cdt 操纵子，但缺乏 cdt 编码基因（A、B 和 C）的分离株比例因研究人群而异。本研究的目的是检测从西非青少年人群中分离的伴放线放线杆菌分离株的血清型、Cdt 基因型和 Cdt 活性，并研究伴放线放线杆菌携带状态与附着丧失（AL）进展之间的关系。
通过 PCR 检测 249 株来自加纳青少年的伴放线放线杆菌分离株的血清型和 cdt 基因型。通过暴露培养细胞的 DNA 染色检测 Cdt 毒素的活性，并通过流式细胞术进行记录。在基线和两年随访时检查参与者的牙周状况。
在检测的 79%的伴放线放线杆菌分离株中检测到所有三种 cdt 编码基因的存在。所有这些分离株均显示出显著的 Cdt 活性。两种不同的 cdt 基因型（存在和不存在所有三种 cdt 编码基因）表现出与血清型相关的分布模式。伴放线放线杆菌的存在与 AL 的进展显著相关（OR = 5.126；95%CI = [2.994-8.779]，p<0.001）。
从加纳青少年中分离的伴放线放线杆菌显示出与基于其他先前研究人群的结果一致的血清型和 cdt 基因型分布。伴放线放线杆菌的存在与疾病进展显著相关，特别是 b 血清型，而与疾病进展的相关性与 cdt 基因型和 Cdt 活性无关。
