Cloning and expression of Listeria monocytogenes hly in Lactococcus lactis

The hly gene is one of the most important virulence factors of Listeria monocytogenes encoding listeriolysin O (LLO). LLO is a potent immunogenic protein eliciting both cellular and humoral immunity and has manyother functions besides hemolytic activity. This protein mediates the bacterial escape to the cytoplasm by disruption of phagosomal membrane leading to intracellular survival and proliferation of L. monocytogenes. On the other hand, Lactococcus lactis is a lactic acid bacterium which has many applications in expression of recombinant proteins. Our aim in this study was expression of recombinant LLO in L. lactis strain. Initially, the pTG19-T plasmid which is a T/A cloning vectorwas employed and then pNZ8110 was used as a Lactococcal secretional expression plasmid to clone L. monocytogenese hly gene by restriction enzymes cutting and ligation method. After cloning and propagation in E. coli MC1061 intermediate host, it was electro-transformed into L. lactis. Expression of LLO was confirmed by SDS-PAGE and western blot.