Vantaux Amélie, Péneau Julie, Cooper Caitlin A, Kyle Dennis E, Witkowski Benoit, Maher Steven P
Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia.
Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, United States.
Front Microbiol. 2022 Sep 23;13:976606. doi: 10.3389/fmicb.2022.976606. eCollection 2022.
, one species of parasite causing human malaria, forms a dormant liver stage, termed the hypnozoite, which activate weeks, months or years after the primary infection, causing relapse episodes. Relapses significantly contribute to the vivax malaria burden and are only killed with drugs of the 8-aminoquinoline class, which are contraindicated in many vulnerable populations. Development of new therapies targeting hypnozoites is hindered, in part, by the lack of robust methods to continuously culture and characterize this parasite. As a result, the determinants of relapse periodicity and the molecular processes that drive hypnozoite formation, persistence, and activation are largely unknown. While previous reports have described vastly different liver-stage growth metrics attributable to which hepatocyte donor lot is used to initiate culture, a comprehensive assessment of how different patient isolates behave in the same lots at the same time is logistically challenging. Using our primary human hepatocyte-based liver-stage culture platform, we aimed to simultaneously test the effects of how hepatocyte donor lot and patient isolate influence the fate of sporozoites and growth of liver schizonts. We found that, while environmental factors such as hepatocyte donor lot can modulate hypnozoite formation rate, the case is also an important determinant of the proportion of hypnozoites observed in culture. In addition, we found schizont growth to be mostly influenced by hepatocyte donor lot. These results suggest that, while host hepatocytes harbor characteristics making them more- or less-supportive of a quiescent versus growing intracellular parasite, sporozoite fating toward hypnozoites is isolate-specific. Future studies involving these host-parasite interactions, including characterization of individual strains, should consider the impact of culture conditions on hypnozoite formation, in order to better understand this important part of the parasite's lifecycle.
间日疟原虫，一种导致人类疟疾的寄生虫，会形成一种休眠的肝期，称为休眠子，它在初次感染数周、数月或数年之后被激活，引发复发。复发对间日疟负担有显著影响，并且只有8-氨基喹啉类药物才能杀死休眠子，但这类药物在许多易感人群中是禁忌的。针对休眠子的新疗法的开发受到阻碍，部分原因是缺乏持续培养和鉴定这种寄生虫的可靠方法。因此，复发周期的决定因素以及驱动休眠子形成、持续存在和激活的分子过程在很大程度上是未知的。虽然之前的报告描述了由于使用不同批次的肝细胞供体启动培养而导致的肝期生长指标存在巨大差异，但对不同患者分离株在同一批次肝细胞中同时表现的全面评估在后勤方面具有挑战性。利用我们基于原代人肝细胞的肝期培养平台，我们旨在同时测试肝细胞供体批次和患者分离株如何影响子孢子的命运以及肝内裂殖体的生长。我们发现，虽然诸如肝细胞供体批次等环境因素可以调节休眠子形成率，但病例也是培养中观察到的休眠子比例的一个重要决定因素。此外，我们发现裂殖体生长主要受肝细胞供体批次的影响。这些结果表明，虽然宿主肝细胞具有一些特征，使其对静止或生长的细胞内寄生虫或多或少具有支持性，但子孢子向休眠子的分化具有分离株特异性。未来涉及这些宿主 - 寄生虫相互作用的研究，包括对单个菌株的表征，应考虑培养条件对休眠子形成的影响，以便更好地理解寄生虫生命周期的这一重要部分。
