Caracterização molecular e funcional da proteína micronema 10 de Neospora caninum

Abstract

Neospora caninum is an obligate intracellular protozoan of the phylum Apicomplexa and the etiological agent of neosporosis, a disease of worldwide distribution that primarily affects dogs and cattle, causing significant economic losses. Parasites of this phylum possess a specialized apical complex composed of secretory organelles such as micronemes, which are essential for host cell adhesion and invasion. Microneme proteins (MICs) play a central role in the early stages of infection by mediating specific interactions between the parasite and the host. Among them, MIC10 stands out as a protein located in the apical region and is potentially involved in parasite adhesion and invasion; however, its function in N. caninum remains poorly characterized. This study aimed to evaluate the role of microneme protein 10 (MIC10) during N. caninum infection. Using CRISPR-Cas9-mediated genome editing, we fused an epitope tag to the C-terminal region of the protein, which allowed us to confirm the predicted subcellular localization of MIC10. We also generated a MIC10-deficient parasite line (Δmic10) and observed a reduction in host cell invasion, associated with a significant decrease in intracellular replication capacity. In vivo assays using a murine experimental model demonstrated that animals infected with Δmic10 knockout parasites exhibited a higher parasite burden during the acute phase of infection (24 hours), whereas parasite load was significantly reduced in brain tissue during the chronic phase (30 days) compared to mice infected with the parental strain. In conclusion, this study describes the molecular and functional characteristics of MIC10 in N. caninum and highlights its relevance in the host cell invasion process, making it a potential target for studies aimed at the prophylaxis and control of infection.