CONICET | Buscador de Institutos y Recursos Humanos

Virus-like Particles (VLPs) vaccines show a strong ability to enhance adaptive immune responses. Since Giardia variant-surface proteins (VSPs) protect the parasite from the harsh environmental conditions of the gastrointestinal tract and have a remarkable intrinsic immunogenicity, we hypothesized that efficient oral vaccines can be generated by combining the benefits of Giardia VSPs with the advantages of particulate immunogens like VLPs. We thus developed VSP-pseudotyped VLPs and evaluated their ability to induce activation of dendritic cells (DCs). Enveloped VLPs comprising MLV GAG capside protein fused to GFP were produced in HEK cells and the recombinant extracellular domain of VSP1267 (rΔVSP) was produced in insect cells. Expression of different activation parameters were tested by incubation of BMDCs (from WT or TLR4-/- mice) with either rΔVSP, naked- or pseudotyped-VLPs. VSP1267-pseudotyped VLPs showed higher levels of expression of the co-stimulatory molecules CD40 and CD86, higher production of IL-4, IL-6, IL-10, TNF and nitric oxide, as well as higher VLP up-take by DCs when were compared to naked-VLPs, indicating that the presence of VSPs on the envelope of VLPs improved its immunogenicity. Conversely, even though rΔVSP was able to increase CD40 and CD86 levels, it only induced a slight increase of TNF. Therefore, despite VSPs per se show immunostimulating properties, these effects are significantly increased when they were covering VLPs.Since rΔVSP activated TLR4 in the HEK-blue reporter system and VSPs/VSP-VLPs effects were markedly reduced when BMDCs from TLR4-/- mice were used, this receptor should mediate the activity of these molecules.