Elongation factor 1-alpha is released into the culture medium during growth of Giardia intestinalis trophozoites

► We identified two secreted Giardia proteins; elongation factor-1 alpha (EF-1α) and arginine deiminase (ADI). ► Two genes in the Giardia genome encode EF-1α. Promoter luciferase-fusions showed that both genes are transcribed in trophozoites. ► The EF-1α protein localizes to the nuclear region but it re-localizes to the cytoplasm during host-cell interaction. ► Recombinant EF-1α is recognized by serum from giardiasis patients.