Jha Bijay Kumar, Varikuti Sanjay, Verma Chaitenya, Shivahare Rahul, Bishop Nicholas, Dos Santos Gregory P, McDonald Jacquelyn, Sur Aakash, Myler Peter J, Schenkman Sergio, Satoskar Abhay R, McGwire Bradford S
Division of Infectious Diseases, Department of Medicine, Wexner Medical Center, The Ohio State University, Columbus, OH, USA.
Departments of Pathology and Microbiology, Wexner Medical Center, The Ohio State University, Columbus, OH, USA.
NPJ Vaccines. 2023 Apr 25;8(1):63. doi: 10.1038/s41541-023-00647-5.
Human infection with the protozoan parasite Trypanosoma cruzi causes Chagas disease for which there are no prophylactic vaccines. Cyclophilin 19 is a secreted cis-trans peptidyl isomerase expressed in all life stages of Trypanosoma cruzi. This protein in the insect stage leads to the inactivation of insect anti-parasitic peptides and parasite transformation whereas in the intracellular amastigotes it participates in generating ROS promoting the growth of parasites. We have generated a parasite mutant with depleted expression of Cyp19 by removal of 2 of 3 genes encoding this protein using double allelic homologous recombination. The mutant parasite line failed to replicate when inoculated into host cells in vitro or in mice indicating that Cyp19 is critical for infectivity. The mutant parasite line also fails to replicate in or cause clinical disease in immuno-deficient mice further validating their lack of virulence. Repeated inoculation of mutant parasites into immuno-competent mice elicits parasite-specific trypanolytic antibodies and a Th-1 biased immune response and challenge of mutant immunized mice with virulent wild-type parasites is 100% effective at preventing death from acute disease. These results suggest that parasite Cyp19 may be candidate for small molecule drug targeting and that the mutant parasite line may warrant further immunization studies for prevention of Chagas disease.
人类感染原生动物寄生虫克氏锥虫会引发恰加斯病，目前尚无预防性疫苗。亲环蛋白19是一种分泌型顺反肽基异构酶，在克氏锥虫的所有生命阶段均有表达。该蛋白在昆虫阶段会导致昆虫抗寄生虫肽失活并促进寄生虫转化，而在细胞内无鞭毛体中，它参与产生活性氧，促进寄生虫生长。我们通过双等位基因同源重组去除了编码该蛋白的3个基因中的2个，从而构建了一个亲环蛋白19表达缺失的寄生虫突变体。该突变寄生虫系在体外接种到宿主细胞中或接种到小鼠体内时均无法复制，这表明亲环蛋白19对感染性至关重要。该突变寄生虫系在免疫缺陷小鼠中也无法复制或引发临床疾病，进一步证实了它们缺乏毒力。将突变寄生虫反复接种到免疫健全的小鼠体内会引发寄生虫特异性溶锥虫抗体和以Th-1为主的免疫反应，用强毒野生型寄生虫攻击突变免疫小鼠可100%有效预防急性疾病导致的死亡。这些结果表明，寄生虫亲环蛋白19可能是小分子药物靶向治疗的候选靶点，并且该突变寄生虫系可能值得进一步开展免疫研究以预防恰加斯病。
