Theileria annulata sporozoite targets

Area of Science:

• Immunology
• Parasitology
• Cell Biology

Background:

• Bovine peripheral blood mononuclear cells (PBMC) infected with Theileria annulata sporozoites are characterized as MHC class II+ mature macrophages.
• Theileria annulata is an important protozoan parasite causing tropical theileriosis in cattle.

Purpose of the Study:

• To investigate the infectivity of Theileria annulata sporozoites in different subpopulations of bovine monocytes.
• To understand the phenotypic alterations in monocytes following infection.

Main Methods:

• Monocyte subpopulations were isolated using magnetic cell sorting (MACS) after labeling with specific monoclonal antibodies (MoAb).
• Infection efficiency of sporozoites in elastin receptor positive and negative monocyte populations was assessed.
• Flow cytometry was used to analyze changes in cell surface markers like MHC class II, elastin receptor, immature/mature markers, and CD14.

Main Results:

• Theileria annulata sporozoites infected both immature and mature bovine monocytes, with a higher preference for mature cells.
• Sporozoites infected elastin receptor positive and negative cells equally, suggesting elastin receptor is not a primary entry ligand.
• Infected immature monocytes downregulated elastin receptor and immature markers, acquiring mature characteristics.
• All infected monocytes lost CD14 expression.

Conclusions:

• Theileria annulata sporozoites exhibit tropism for specific monocyte subpopulations, particularly mature ones.
• Monocyte infection by T. annulata leads to significant phenotypic modulation, including loss of CD14 and changes in maturation markers.
• These alterations in monocyte phenotype following infection may play a crucial role in the pathogenesis of theileriosis.