Unraveling the potential of Giardia extracellular vesicles as a vaccine candidat

In this study, we investigated the role of Giardia EVs in cellular communication and their potential as vaccine candidates. Our findings revealed that Giardia EVs activate pro-inflammatory signalling cascades, including SAPK/JNK and ERK1/ERK2, as well as the NF-kB pathway, resulting in IκB-α degradation and p65 translocation to the nucleus, in mouse macrophages. Moreover, Giardia EVs increased the expression of genes encoding pro-inflammatory molecules, such as Il1β, Il6, Il4, Ptgs2, Nos2, and Tnf. Interestingly, Giardia EVs enhanced the maturation status of human Mo-DCs and significantly increased T-cell proliferation with a Th1 profile. Immunization studies demonstrated that Giardia EVs elicited antigen-specific antibodies, with IgG subclasses indicating a balance Th1/ Th2 response. Mass spectrometry analysis identified EV proteins (22 KDa and 50 KDa) that bind to serum antibodies of immunized mice including elongation factor 1-alpha, Alpha-7.3 giardin, tubulin, and Variant Surface Proteins (VSP), known antigenic proteins in Giardia infections. Overall, our results indicated that Giardia EVs modulate innate immune cells in vitro, induce antibody-based immune response in vivo, and contain conserved immunogenic proteins. Consequently, Giardia EVs hold promise as a cell-free vaccine candidate for giardiasis.