Zhou Bei-Bei, Dong Hong-Jie, Sun Hang, Xie Xiao-Man, Xie Huan-Huan, Zhu Wen-Ju, Li Ya-Nan, Xu Chao, Cao Jian-Ping, Zhao Gui-Hua, Yin Kun
National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); Shandong Institute of Parasitic Diseases, Jining, 272033, China.
Key Laboratory of Parasite and Vector Biology, National Health Commission of the People's Republic of China, Shanghai, 200025, China.
Parasit Vectors. 2025 May 26;18(1):190. doi: 10.1186/s13071-025-06819-7.
Toxoplasma gondii can cause severe damage to immunodeficient hosts, and also compromise brain structure and function in immunocompetent hosts during latent infection. In China, the two different isolates, Chinese I (ToxoDB#9) and Chinese III are dominant epidemic strains widely spreading in humans and domestic animals and can lead to latent infection in host brain tissues, but the comparison of their manipulation patterns and mechanisms remains unclear.
Tachyzoites of the TgWh6 (Wh6) strain and the TgCtLHG (LHG) strain were used for establishing in vitro infection models within mouse microglia BV2 cells, and the differences in their invasion and proliferation patterns were observed. C57BL/6 J mice were used to establish in vivo latent infection models. After behavioral tests, the differential expressed transcripts (DETs) of the infected and control animals' cerebral cortex were sequenced by Nanopore RNA-seq. Functional differences of DETs were analyzed by Gene Ontology enrichment analysis (GO), Kyoto Encyclopedia of Genes and Genomes enrichment analysis (KEGG), and protein-protein interaction (PPI) and cluster analysis. Expression of the key candidates were verified by quantitative polymerase chain reaction (qPCR).
In our infection models, we found that Wh6 had more vigorous invasion and proliferation abilities in vitro, while LHG had a greater ability to form cysts in vivo. In the latent infection phase, behavioral changes, including spatial working memory, cognitive and motor abilities, and anxiety, were observed in both Wh6 and LHG infected mice; however, the LHG group showed more serious anxiety. Among DETs, genes related to major histocompatibility complex (MHC) class II molecules were significantly upregulated in the infected mice, while genes related to synaptic transmission and neurodegenerative diseases were downregulated in the infected groups. The downregulated DETs of Sept4, Kcng4, Unc13c, and Prkcg in the WH6 group, which are related to synaptic transmission, and Ndrg2 and Arc in the LHG group, which are related to neurodegenerative diseases, were selected to be the key candidates in the latent infection phase.
Compared with WH6, although LHG has a milder invasion ability, it can cause increased behavioral disorders in hosts. Genes related to synaptic transmission and neurodegenerative diseases may be the main causes of host mental and behavioral disorders.
弓形虫可对免疫缺陷宿主造成严重损害，在潜伏感染期间也会损害免疫健全宿主的脑结构和功能。在中国，两种不同的分离株，即中国I株（ToxoDB#9）和中国III株，是在人类和家畜中广泛传播的优势流行株，可导致宿主脑组织潜伏感染，但其操控模式和机制的比较仍不清楚。
使用TgWh6（Wh6）株和TgCtLHG（LHG）株的速殖子在小鼠小胶质细胞BV2中建立体外感染模型，观察它们侵袭和增殖模式的差异。使用C57BL/6 J小鼠建立体内潜伏感染模型。行为测试后，通过纳米孔RNA测序对感染和对照动物大脑皮层的差异表达转录本（DET）进行测序。通过基因本体富集分析（GO）、京都基因与基因组百科全书富集分析（KEGG）、蛋白质-蛋白质相互作用（PPI）和聚类分析来分析DET的功能差异。通过定量聚合酶链反应（qPCR）验证关键候选基因的表达。
在我们的感染模型中，我们发现Wh6在体外具有更强的侵袭和增殖能力，而LHG在体内具有更强的形成包囊的能力。在潜伏感染阶段，Wh6和LHG感染的小鼠均出现行为变化，包括空间工作记忆、认知和运动能力以及焦虑；然而，LHG组的焦虑更为严重。在DET中，与主要组织相容性复合体（MHC）II类分子相关的基因在感染小鼠中显著上调，而与突触传递和神经退行性疾病相关的基因在感染组中下调。选择与突触传递相关的WH6组中的Sept4、Kcng4、Unc13c和Prkcg以及与神经退行性疾病相关的LHG组中的Ndrg2和Arc的下调DET作为潜伏感染阶段的关键候选基因。
与Wh6相比，LHG虽然侵袭能力较弱，但可导致宿主行为障碍增加。与突触传递和神经退行性疾病相关的基因可能是宿主精神和行为障碍的主要原因。
