Recombinant Lactococcus lactis expressing haemagglutinin from a polish avian H5N1 isolate and its immunological effect in preliminary animal trials.

Abstract

Lactic acid bacteria (LAB) are Gram-positive, non-pathogenic microorganisms that are gaining much interest as antigen producers for development of live vaccine vectors. Heterologous proteins of different origin have been successfully expressed in such LAB species as Lactococcus lactis. Recombinant L. lactis strains have been shown to induce specific local and systemic immune responses against various antigens. Our study aimed at constructing a L. lactis strain expressing haemagglutinin of the Polish avian H5H1 influenza isolate and examining its effect on animals. Expression of the cloned H5 gene was achieved using the nisin-controlled gene expression system. Detection of the intracellular H5 antigen produced in L. lactis was performed by Western blot analysis and confirmed using Mass Spectrometry. The potential of L. lactis recombinant cells to induce an immune response was examined by setting up preliminary immunization trials on mice and chicken. Obtained sera were tested for specific antibodies by ELISA assays. The results of these preliminary studies are a promising step toward developing a vaccine against the avian bird flu using Lactococcus lactis cells as bioreactors for efficient antigen production and delivery to the mucosal surface.