State Key Laboratory for Zoonotic Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Institute of Zoonosis, and College of Veterinary Medicine, Jilin University, Changchun 130062, China.
State Key Laboratory for Zoonotic Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Institute of Zoonosis, and College of Veterinary Medicine, Jilin University, Changchun 130062, China.
Vet Parasitol. 2024 Apr;327:110117. doi: 10.1016/j.vetpar.2024.110117. Epub 2024 Jan 17.
Neospora caninum, an obligate intracellular parasitic protozoan discovered by Dubey in 1988, is the pathogen of neosporosis, which causes neurological symptoms in dogs and abortions in cows. Since there is no effective drug or vaccine against N. caninum, a deeper understanding of the molecules critical to parasite survival inside host cells is necessary. This study aimed to determine the role of N. caninum peroxiredoxin 1 (NcPrx1) in maintaining redox homeostasis and virulence of N. caninum. By determining the localization of NcPrx1 protein and establishing NcPrx1 gene knockout strain (ΔNcPrx1), the roles of NcPrx1 in N. caninum for invasion, replication, growth, oxidative stress, as well as pathogenicity were investigated. Our results showed that a predicted Alkyl Hydroperoxide1 (AHP1) domain was found in the amino acid sequence of NcPrx1, which displayed a high degree of similarity to homologs of several protozoa. Immunofluorescence assay (IFA) indicated that NcPrx1 was a cytoplasmic protein in N. caninum tachyzoites. Compared to wild type (WT) strain, ΔNcPrx1 strain showed reduced plaque area, invasion and egress rates. Reactive oxygen species (ROS) and malondialdehyde (MDA) were accumulated, and total antioxidant capacity (T-AOC) was attenuated in ΔNcPrx1 tachyzoites, which indicated that ΔNcPrx1 strain was more sensitive to oxidative stress. Furthermore, ΔNcPrx1 strain-infected C57BL/6 mice showed improved survival rate, reduced parasite burden, alleviated pathological changes in tissues, and decreased secretions of IL-6, IL-12, TNF-α, and IFN-γ in serum compared to the WT strain group. These findings suggested that NcPrx1 was a virulence factor of N. caninum which played an important role in maintaining the redox homeostasis of the parasite.
刚地弓形虫是 1988 年由 Dubey 发现的一种专性细胞内寄生的原生动物，是引起犬神经症状和牛流产的弓形体病的病原体。由于目前尚无有效的药物或疫苗来对抗刚地弓形虫，因此深入了解寄生虫在宿主细胞内生存所必需的分子是必要的。本研究旨在确定刚地弓形虫过氧化物酶 1（NcPrx1）在维持刚地弓形虫的氧化还原平衡和毒力中的作用。通过确定 NcPrx1 蛋白的定位并建立 NcPrx1 基因敲除株（ΔNcPrx1），研究了 NcPrx1 在刚地弓形虫入侵、复制、生长、氧化应激以及致病性中的作用。我们的结果表明，在 NcPrx1 的氨基酸序列中发现了一个预测的烷基过氧化氢酶 1（AHP1）结构域，该结构域与几种原生动物的同源物具有高度相似性。免疫荧光分析（IFA）表明 NcPrx1 是刚地弓形虫速殖子中的细胞质蛋白。与野生型（WT）株相比，ΔNcPrx1 株的蚀斑面积、入侵和逸出率降低。ΔNcPrx1 速殖子中活性氧（ROS）和丙二醛（MDA）积累，总抗氧化能力（T-AOC）减弱，表明ΔNcPrx1 株对氧化应激更敏感。此外，与 WT 株感染组相比，ΔNcPrx1 株感染的 C57BL/6 小鼠的存活率提高，寄生虫负荷降低，组织病理变化减轻，血清中白细胞介素-6（IL-6）、白细胞介素-12（IL-12）、肿瘤坏死因子-α（TNF-α）和干扰素-γ（IFN-γ）的分泌减少。这些发现表明 NcPrx1 是刚地弓形虫的毒力因子，在维持寄生虫的氧化还原平衡中发挥重要作用。
