Malaria, caused by Plasmodium species, remains a major global health burden. The spleen is the central organ for clearance of infected red blood cells and regulation of immunity, yet paradoxically also serves as a site of parasite sequestration. Splenic fibroblasts may contribute to this process through adhesion mechanisms, but their role remains poorly defined. This study investigated P. yoelii tryptophan-rich antigen 7 (PyTRAg7), a member of the TRAg protein family, in splenic parasite–host interactions. TRAgs constitute a conserved protein family present in multiple Plasmodium species, including human malaria parasites, suggesting the relevance of PyTRAg7-associated mechanisms to human infection. Using protein binding assays and gene-edited parasites, PyTRAg7 was shown to interact with vimentin on mouse splenic fibroblasts, activating NF-κB p65 signaling and increasing ICAM-1 and integrin β1 expression. Deletion of PyTRAg7 reduced infected red blood cells adhesion to mouse splenic fibroblasts, lowered splenic parasite burden, delayed parasitemia onset, and prolonged host survival. Histological analysis showed preserved splenic architecture and reduced hemozoin deposition in the absence of PyTRAg7. The murine P. yoelii model was used due to its genetic tractability and its suitability for dissecting spleen-dependent sequestration mechanisms not easily studied in human malaria parasites. These findings identify PyTRAg7 as a key mediator of fibroblast–parasite interactions that promote cytoadherence and splenic remodeling, offering a potential target for malaria intervention.
Members of genus Acanthamoeba are widely distributed in the environment. Some are pathogenic and cause keratitis and fatal granulomatous amoebic encephalitis. In this study, we isolated an Acanthamoeba CJW/W1 strain from tap water in Wuxi, Jiangsu Province, China. Its 18S rDNA was sequenced and a phylogenetic tree was constructed. The isolated cysts belonged to morphologic group II. Comparison of 18S rDNA sequences of CJW/W1 strain and other isolates showed high similarity (99.7%) to a clinical isolate Asp, KA/E28. A phylogeny analysis confirmed this isolate belonged to the pathogenic genotype T4, the most common strain associated with Acanthamoeba-related diseases. This is the first report of an Acanthamoeba strain isolated from tap water in Wuxi, China. Acanthamoeba could be a public health threat to the contact lens wearers and, therefore, its prevalence should be monitored.
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