Department of Periodontology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
Microbiol Immunol. 2021 Mar;65(3):101-114. doi: 10.1111/1348-0421.12864. Epub 2021 Feb 16.
Aggregatibacter actinomycetemcomitans is a facultative anaerobic Gram-negative bacterium associated with periodontal diseases, especially aggressive periodontitis. The virulence factors of this pathogen, including adhesins, exotoxins, and endotoxin, have been extensively studied. However, little is known about their gene expression mode in the host. Herein, we investigated whether culture conditions reflecting in vivo environments, including serum and saliva, alter expression levels of virulence genes in the strain HK1651, a JP2 clone. Under aerobic conditions, addition of calf serum (CS) into a general medium induced high expression of two outer membrane proteins (omp100 and omp64). The high expression of omp100 and omp64 was also induced by an iron-limited medium. RNA-seq analysis showed that the gene expressions of several factors involved in iron acquisition were increased in the CS-containing medium. When HK1651 was grown on agar plates, genes encoding many virulence factors, including the Omps, cytolethal distending toxin, and leukotoxin, were differentially expressed. Then, we investigated their expression in five other A. actinomycetemcomitans strains grown in general and CS-containing media. The expression pattern of virulence factors varied among strains. Compared with the other five strains, HK1561 showed high expression of omp29 regardless of the CS addition, while the gene expression of leukotoxin in HK1651 was higher only in the medium without CS. HK1651 showed reduced biofilm in both CS- and saliva-containing media. Coaggregation with Fusobacterium nucleatum was remarkably enhanced using HK1651 grown in the CS-containing medium. Our results indicate that the expression of virulence factors is altered by adaptation to different conditions during infection.
伴放线放线杆菌是一种兼性厌氧革兰氏阴性菌，与牙周病，尤其是侵袭性牙周炎有关。该病原体的毒力因子，包括黏附素、外毒素和内毒素，已得到广泛研究。然而，对于其在宿主中的基因表达模式知之甚少。在此，我们研究了反映体内环境的培养条件，包括血清和唾液，是否会改变 JP2 克隆株 HK1651 的毒力基因表达水平。在需氧条件下，一般培养基中添加牛血清（CS）可诱导两种外膜蛋白（omp100 和 omp64）的高表达。缺铁培养基也能诱导 omp100 和 omp64 的高表达。RNA-seq 分析表明，含铁介质中参与铁摄取的几个因子的基因表达增加。当 HK1651 在琼脂平板上生长时，编码许多毒力因子的基因，包括 Omps、细胞致死扩张毒素和白细胞毒素，表达情况不同。然后，我们研究了它们在其他五种在一般培养基和 CS 培养基中生长的伴放线放线杆菌菌株中的表达情况。毒力因子的表达模式在菌株间存在差异。与其他五种菌株相比，无论是否添加 CS，HK1561 的 omp29 表达均较高，而 HK1651 中的白细胞毒素基因表达仅在不含 CS 的培养基中较高。HK1651 在含 CS 和唾液的培养基中的生物膜形成减少。在 CS 存在的情况下，HK1651 与伴放线放线杆菌的共聚明显增强。我们的结果表明，毒力因子的表达通过适应感染过程中的不同条件而改变。
