The non-pathogenic ciliate Tetrahymena thermophila is one of the best-characterized
unicellular eucaryotes used in various research fields. Previous work has shown that this unicellular
organism provides many biological features to become a high-quality expression system, like
multiplying to high cell densities with short generation times in bioreactors. In addition, the
expression of surface antigens from the malaria parasite Plasmodium falciparum and the ciliate
Ichthyophthirius multifiliis suggests that T. thermophila might play an important role in vaccine
development. However, the expression of functional mammalian or human enzymes remains so far
to be seen.