as an Antigen Delivery Platform: Dendritic Cell Maturation after Infection with a Clone Engineered to Express the SARS-CoV-2 Spike Protein.

BACKGROUND

Protozoa of the genus are characterized by their capacity to target macrophages and Dendritic Cells (DCs). These microorganisms could thus be exploited for the delivery of antigens to immune cells. is regarded as a non-pathogenic species; it was previously used as a biofactory for protein production and has been considered as a candidate vaccine or as an antigen delivery platform. However, results on the type of immune polarization determined by are still inconclusive.

METHODS

DCs were derived from human monocytes and exposed to live , using both the non-engineered P10 strain, and the same strain engineered for expression of the spike protein from SARS-CoV-2. We then determined: (i) parasite internalization in the DCs; and (ii) the capacity of the assayed strains to activate DCs and the type of immune polarization.

RESULTS

Protozoan parasites from both strains were effectively engulfed by DCs, which displayed a full pattern of maturation, in terms of MHC class II and costimulatory molecule expression. In addition, after parasite infection, a limited release of Th1 cytokines was observed.

CONCLUSIONS

Our results indicate that could be used as a vehicle for antigen delivery to DCs and to induce the maturation of these cells. The limited cytokine release suggests as a neutral vaccine vehicle that could be administered in association with appropriate immune-modulating molecules.