RecombinantLactococcus lactisExpressing Haemagglutinin from a Polish Avian H5N1 Isolate and Its Immunological Effect in Preliminary Animal Trials

Abstract

Lactic acid bacteria (LAB) are Gram-positive, nonpathogenic 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 various LAB species, includingLactococcus lactis. RecombinantL. lactisstrains have been shown to induce specific local and systemic immune responses against various antigens. Our study aimed at constructing aL. lactisstrain expressing haemagglutinin of a Polish avian H5H1 influenza isolate and examining its effect on animals. Expression of the clonedH5gene was achieved using the nisin-controlled gene expression system. Detection of the intracellular H5 antigen produced inL. lactiswas performed by Western blot analysis and confirmed using mass spectrometry. The potential ofL. lactisrecombinant cells to induce an immune response was examined by setting up preliminary immunization trials on chickens and mice. Obtained sera were tested for specific antibodies by ELISA assays. The results of these studies are a promising step toward developing a vaccine against the bird flu usingLactococcus lactiscells as bioreactors for efficient antigen production and delivery to the mucosal surface.