Adjuvant-enhanced antibody and cellular responses to inclusion bodies expressing FhSAP2 correlates with protection of mice to Fasciola hepatica.
Adjuvant-enhanced antibody and cellular responses to inclusion bodies expressing FhSAP2 correlates with protection of mice to Fasciola hepatica.
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DOI：
10.1016/j.exppara.2015.11.002
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发表时间：
2016-01
影响因子：
2.1
通讯作者：
Espino AM
中科院分区：
文献类型：
--
作者：
Rivera F;Espino AM
肝片形吸虫saposin样蛋白-2 (FhSAP2) 是一种在肝片形吸虫各个发育阶段差异表达的蛋白质。重组 FhSAP2 已被证明当在弗氏佐剂中皮下 (SC) 给药时，可以在小鼠和兔子中诱导部分保护。由于 FhSAP2 在细菌中以包涵体 (IB) 的形式过度表达，我们分离了表达 FhSAP2 的 IB，并测试了在两种不同佐剂（QS-21 和 Montanide™ ISA720）乳化的小鼠中皮下注射时的免疫原性。动物接受三次含有20μg蛋白质的注射，间隔两周，第三次注射后4周，通过口服途径感染10只肝吸虫囊蚴。与接种佐剂的感染对照相比，FhSAP2-IB 诱导的保护百分比估计在 60.0-62.5% 之间。通过测定实验动物血清中IgG1和IgG2a抗体以及IL-4和IFNγ细胞因子的水平，发现与接种佐剂的感染对照组相比，FhSAP2-IBs接种组的Th1和Th2免疫反应均显着增强。与 FhSAP2-IBs 疫苗接种动物相比，佐剂疫苗接种组的 IgG1 与 IgG2a 比率以及 IL-4 与 IFNγ 比率显着降低，这表明 Th2 免疫反应水平较高。无论使用何种佐剂，接种 FhSAP2-IB 的动物比佐剂对照组表现出显着更高的存活率和更少的肝损伤。这项研究表明，FhSAP2 具有作为肝镰刀菌疫苗的潜力，并且该分子引起的保护可能与 CD4-Th1 细胞驱动的机制有关。
Fasciola hepatica saposin-like protein-2 (FhSAP2) is a protein differentially expressed in various developmental stages of F. hepatica. Recombinant FhSAP2 has demonstrated the induction of partial protection in mice and rabbits when it is administered subcutaneously (SC) in Freund’s adjuvant. Because FhSAP2 is overexpressed in bacteria in the form of inclusion bodies (IBs), we isolated IBs expressing FhSAP2 and tested their immunogenicity when administered SC in mice emulsified in two different adjuvants: QS-21 and Montanide™ ISA720. Animals received three injections containing 20μg of protein two weeks apart and 4 weeks after the third injection, mice were infected with 10 F. hepatica metacercariae by oral route. The percentages of protection induced by FhSAP2-IBs were estimated to be between 60.0–62.5% when compared with adjuvant-vaccinated, infected controls. By determining the levels of IgG1 and IgG2a antibodies and IL-4 and IFNγ cytokines in the serum of experimental animals, it was found that both Th1 and Th2 immune responses were significantly increased in the FhSAP2-IBs vaccinated groups compared with the adjuvant-vaccinated, infected control groups. The adjuvant-vaccinated groups had significantly lower IgG1 to IgG2a ratios and lower IL-4 to IFNγ ratios than the FhSAP2-IBs vaccinated animals, which is indicative of higher levels of Th2 immune responses. Irrespective to the adjuvant used, animals vaccinated with FhSAP2-IBs exhibited significantly higher survival percentage and less liver damage than the adjuvant-control groups. This study suggests that FhSAP2 has potential as vaccine against F. hepatica and that the protection elicited by this molecule could be linked to a mechanism driven by the CD4-Th1 cells.