School of Public Health, University of Alberta,11405-87 Avenue, Edmonton, Alberta T6G 1C9, Canada.
Deparment of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta T6G 2E1, Canada.
FEMS Microbiol Ecol. 2020 Oct 1;96(10). doi: 10.1093/femsec/fiaa182.
Helicobacter pylori is a fastidious Gram-negative bacterium that infects over half of the world's population, causing chronic gastritis and is a risk factor for stomach cancer. In developing and rural regions where prevalence rate exceeds 60%, persistence and waterborne transmission are often linked to poor sanitation conditions. Here we demonstrate that H. pylori not only survives but also replicates within acidified free-living amoebal phagosomes. Bacterial counts of the clinical isolate H. pylori G27 increased over 50-fold after three days in co-culture with amoebae. In contrast, a H. pylori mutant deficient in a cagPAI gene (cagE) showed little growth within amoebae, demonstrating the likely importance of a type IV secretion system in H. pylori for amoebal infection. We also demonstrate that H. pylori can be packaged by amoebae and released in extracellular vesicles. Furthermore, and for the first time, we successfully demonstrate the ability of two free-living amoebae to revert and recover viable but non-cultivable coccoid (VBNC)-H. pylori to a culturable state. Our studies provide evidence to support the hypothesis that amoebae and perhaps other free-living protozoa contribute to the replication and persistence of human-pathogenic H. pylori by providing a protected intracellular microenvironment for this pathogen to persist in natural aquatic environments and engineered water systems, thereby H. pylori potentially uses amoeba as a carrier and a vector of transmission.
幽门螺杆菌是一种挑剔的革兰氏阴性细菌，感染了世界上超过一半的人口，导致慢性胃炎，也是胃癌的一个风险因素。在发展中和农村地区，患病率超过 60%，持续性和水传播通常与卫生条件差有关。在这里，我们证明了幽门螺杆菌不仅可以在酸化的自由生活的阿米巴吞噬体中存活，而且还可以复制。在与阿米巴共培养三天后，临床分离株幽门螺杆菌 G27 的细菌数量增加了 50 多倍。相比之下，一种缺失 cagPAI 基因（cagE）的幽门螺杆菌突变体在阿米巴体内生长很少，这表明 IV 型分泌系统在幽门螺杆菌感染阿米巴中可能很重要。我们还证明了幽门螺杆菌可以被阿米巴包裹，并以细胞外囊泡的形式释放。此外，我们首次成功证明了两种自由生活的阿米巴能够使可逆和恢复的存活但非可培养的球形（VBNC）-幽门螺杆菌恢复为可培养状态。我们的研究提供了证据支持这样的假设，即阿米巴和其他可能的自由生活的原生动物通过为这种病原体在自然水生环境和工程水系统中持续存在提供一个受保护的细胞内微环境，从而有助于人类致病性幽门螺杆菌的复制和持续存在，因此，幽门螺杆菌可能利用阿米巴作为传播的载体和媒介。
