Secretion of heterologous proteins of therapeutical interest in Lactococcus lactis

The GRAS (for Generally Regarded As Safe) bacterium, Lactococcus lactis, is a good candidate to produce heterologous proteins of vaccinal, medical or technological interest. The secretion of such proteins would allow a direct contact between the protein and its target and therefore would be a better mode of production than intracellular production. To develop heterologous protein export systems in L. lactis, we used the staphylococcal nuclease. W e combined these secretion tools to the Nisin-Inducible Controlled Expressi on system. We first developed two new expression vectors allowing the induc ible production of Nuc intra- and extracellularly. We then used them to pro duce in L. lactis two heterologous proteins of therapeutical interest: (i) the ovine omega interferon which possesses antiviral properties and which w ill be useful to enhance immune response in the case of the use of L. lacti s as antigen delivery vehicle and (ii) a fusion protein between the Blg41-6 0 epitope and the mature part of Nuc.