Giardiavirus rewires host translation and glycolytic metabolism to support its replication in Giardia duodenalis

Giardia duodenalis is a prevalent intestinal pathogens known to cause giardiasis, a condition characterized by diarrhea and frequently linked to malnutrition and growth impairments in children. The presence of Giardiavirus (GLV) in Giardia strains has been associated with heightened immune cytokine responses in the host compared to the GLV-free strains. However, the transmission mode and biological significance of GLV remain unclear. In this study, by using G. duodenalis DH (GLV-containing) and WBC6 (GLV-free) strains, we demonstrated that the DH strain produced extracellular vesicles (EVs), which originated from unique peripheral vesicle and bead-like structures in the ventrolateral flange. Nanoparticle tracking analysis revealed that GLV infected-G. duodenalis DH strain secreted fewer EVs than the GLV-free WBC6 strain. Biochemical and electron microscopy demonstrated that GLV virions can exploit the Giardia EVs pathway to facilitate their spread among parasites. Giardia uptake of GLV-containing EVs occured through clathrin-mediated endocytosis, leading to rapid infection of trophozoites by GLV. Furthermore, GLV infection enhanced messenger RNA translation efficiency, influencing protein abundance in Giardia trophozoites. The presence of GLV also upregulated the glycolytic pathway, with Giardia enolase closely associated with GLV replication. Importantly, Giardia infected with GLV alleviated the pathogenicity of parasite compared to the GLV-freeGiardia strain. These findings highlight the pivotal role of GLV in regulating Giardia biology, suggesting its potential for informing the development of novel intervention strategies against Giardia infections. Comparative genes translation efficiency on the three species by Monosomes RNA-seq and polysomes RNA-seq analyses

贾第鞭毛虫（Giardia duodenalis）是一种广泛流行的肠道病原体，可引发贾第虫病（giardiasis），该病以腹泻为典型特征，且常与儿童营养不良及生长发育障碍密切相关。研究显示，携带贾第虫病毒（Giardiavirus，GLV）的贾第虫菌株，其宿主的免疫细胞因子反应相较于无GLV菌株更为强烈。然而，GLV的传播途径及其生物学意义目前仍不明确。本研究利用携带GLV的十二指肠贾第虫DH菌株与无GLV的WBC6菌株，证实DH菌株可产生细胞外囊泡（extracellular vesicles，EVs），这类囊泡源自腹侧鞭毛上独特的外周囊泡与珠状结构。纳米颗粒追踪分析表明，感染GLV的十二指肠贾第虫DH菌株分泌的细胞外囊泡数量少于无GLV的WBC6菌株。生化实验与电子显微镜观察结果显示，GLV病毒粒子可借助贾第虫的细胞外囊泡通路，促进其在寄生虫群体内的传播。贾第虫通过网格蛋白介导的内吞作用摄取携带GLV的细胞外囊泡，从而实现GLV对滋养体的快速感染。此外，GLV感染可提升信使RNA（messenger RNA，mRNA）的翻译效率，影响贾第虫滋养体的蛋白丰度。GLV的存在还会上调糖酵解通路，而贾第虫烯醇化酶与GLV的复制过程密切相关。值得注意的是，相较于无GLV的贾第虫菌株，感染GLV的贾第虫可减轻寄生虫的致病力。上述研究结果凸显了GLV在调控贾第虫生物学特性中的关键作用，为开发针对贾第虫感染的新型干预策略提供了潜在可能。本研究通过单核糖体RNA测序（Monosomes RNA-seq）与多核糖体RNA测序（polysomes RNA-seq）分析，对三种物种的基因翻译效率进行了比较研究。