Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands.
Interventional Molecular Imaging Laboratory, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.
mSphere. 2021 Apr 7;6(2):e00218-21. doi: 10.1128/mSphere.00218-21.
Malaria vaccine candidates based on live, attenuated sporozoites have led to high levels of protection. However, their efficacy critically depends on the sporozoites' ability to reach and infect the host liver. Administration via mosquito inoculation is by far the most potent method for inducing immunity but highly impractical. Here, we observed that intradermal syringe-injected sporozoites (SPZ) were 3-fold less efficient in migrating to and infecting mouse liver than mosquito-inoculated sporozoites (SPZ). This was related to a clustered dermal distribution (2-fold-decreased median distance between SPZ and SPZ) and, more importantly, a 1.4-fold (significantly)-slower and more erratic movement pattern. These erratic movement patterns were likely caused by alteration of dermal tissue morphology (>15-μm intercellular gaps) due to injection of fluid and may critically decrease sporozoite infectivity. These results suggest that novel microvolume-based administration technologies hold promise for replicating the success of mosquito-inoculated live, attenuated sporozoite vaccines. Malaria still causes a major burden on global health and the economy. The efficacy of live, attenuated malaria sporozoites as vaccine candidates critically depends on their ability to migrate to and infect the host liver. This work sheds light on the effect of different administration routes on sporozoite migration. We show that the delivery of sporozoites via mosquito inoculation is more efficient than syringe injection; however, this route of administration is highly impractical for vaccine purposes. Using confocal microscopy and automated imaging software, we demonstrate that syringe-injected sporozoites do cluster, move more slowly, and display more erratic movement due to alterations in tissue morphology. These findings indicate that microneedle-based engineering solutions hold promise for replicating the success of mosquito-inoculated live, attenuated sporozoite vaccines.
基于减毒活孢子的疟疾疫苗候选物已导致高水平的保护。然而,它们的功效严重依赖于孢子到达和感染宿主肝脏的能力。通过蚊子接种进行给药是迄今为止最有效的诱导免疫方法,但极不切实际。在这里,我们观察到皮内注射器注射的孢子(SPZ)在迁移到和感染小鼠肝脏方面的效率比蚊子接种的孢子(SPZ)低 3 倍。这与皮内聚集分布(SPZ 之间的中位数距离减少 2 倍)有关,更重要的是,运动模式更慢且更不稳定,速度降低了 1.4 倍(显著)。这些不稳定的运动模式可能是由于注射液体导致真皮组织形态发生改变(细胞间间隙>15 μm),这可能会严重降低孢子的感染力。这些结果表明,新型微体积给药技术有可能复制蚊子接种减毒活孢子疫苗的成功。疟疾仍然对全球健康和经济造成重大负担。作为疫苗候选物的减毒活疟疾孢子的功效严重依赖于其迁移到和感染宿主肝脏的能力。这项工作阐明了不同给药途径对孢子迁移的影响。我们表明,通过蚊子接种来输送孢子比注射器注射更有效;然而,这种给药途径对于疫苗目的来说非常不切实际。我们使用共聚焦显微镜和自动成像软件证明,注射器注射的孢子确实会聚集,移动更慢,并且由于组织形态的改变而显示出更不稳定的运动。这些发现表明,基于微针的工程解决方案有望复制蚊子接种减毒活孢子疫苗的成功。