Rivera Israel, Linz Bodo, Dewan Kalyan K, Ma Longhuan, Rice Christopher A, Kyle Dennis E, Harvill Eric T
Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States.
Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, United States.
Front Microbiol. 2019 Dec 11;10:2839. doi: 10.3389/fmicb.2019.02839. eCollection 2019.
Animal and human pathogens of the genus are not commonly considered to be intracellular pathogens, although members of the closely related classical bordetellae are known to enter and persist within macrophages and have anecdotally been reported to be intracellular in clinical samples. , the species closest to the ancestral lineage of the classical bordetellae, infects a wide range of mammals but is known to have an alternate life cycle, persisting, replicating and disseminating with amoeba. These observations give rise to the hypothesis that the ability for intracellular survival has an ancestral origin and is common among animal-pathogenic and environmental species. Here we analyzed the survival of and defined its transcriptional response to internalization by murine macrophage-like cell line RAW 264.7. Although the majority of the bacteria were killed and digested by the macrophages, a consistent fraction survived and persisted inside the phagocytes. Internalization prompted the activation of a prominent stress response characterized by upregulation of genes involved in DNA repair, oxidative stress response, pH homeostasis, chaperone functions, and activation of specific metabolic pathways. Cross species genome comparisons revealed that most of these upregulated genes are highly conserved among both the classical and non-classical species. The diverse species also shared the ability to survive inside RAW 264.7 cells, with the single exception being the bird pathogen , which has lost several of those genes. Knock-out mutations in genes expressed intracellularly resulted in decreased persistence inside the phagocytic cells, emphasizing the importance of these genes in this environment. These data show that the ability to persist inside macrophage-like RAW 264.7 cells is shared among nearly all species, suggesting that resisting phagocytes may be an ancient mechanism that precedes speciation in the genus and may have facilitated the adaptation of species from environmental bacteria to mammalian respiratory pathogens.
该属的动物和人类病原体通常不被认为是细胞内病原体，尽管已知密切相关的经典博德特氏菌属成员可进入巨噬细胞并在其中持续存在，并且有临床样本中存在细胞内感染的传闻报道。最接近经典博德特氏菌祖先谱系的物种感染多种哺乳动物，但已知具有交替生命周期，可在变形虫中持续存在、复制和传播。这些观察结果引发了这样一种假设，即细胞内存活能力具有祖先起源，并且在动物致病和环境物种中很常见。在这里，我们分析了该物种的存活情况，并确定了其对鼠巨噬细胞样细胞系RAW 264.7内化的转录反应。尽管大多数细菌被巨噬细胞杀死和消化，但仍有一部分细菌在吞噬细胞内存活并持续存在。内化促使激活一种显著的应激反应，其特征是参与DNA修复、氧化应激反应、pH稳态、伴侣功能的基因上调，以及特定代谢途径的激活。跨物种基因组比较显示，这些上调基因中的大多数在经典和非经典物种中都高度保守。不同的物种也具有在RAW 264.7细胞内存活的能力，唯一的例外是鸟类病原体，它已经失去了其中一些基因。细胞内表达基因的敲除突变导致在吞噬细胞内的持续能力下降，强调了这些基因在这种环境中的重要性。这些数据表明，几乎所有物种都具有在巨噬细胞样RAW 264.7细胞内存活的能力，这表明抵抗吞噬细胞可能是该属物种形成之前的一种古老机制，并且可能促进了该物种从环境细菌向哺乳动物呼吸道病原体的适应。
