Cloning of EprA1 gene of Aeromonas hydrophila in Lactococcus lactis

Bacterial-based systems as live vectors for the delivery of heterologous antigens offer a number of advantages as vaccination strategies. Developments in genetic engineering have given Gram-positive lacticacid bacteria (LAB) the advantage of being used as a host expression system for antigen delivery to inducethe immune response. A fragment containing the full length of the “eprA1” gene, encoding a temperaturestable metalloprotease of Aeromonas hydrophila isolated from fish was amplified by polymerase chain reaction (PCR) using the genomic DNA of this bacterium as template. The amplified 1038 bp fragment was digested by PstI and HindIII, followed by ligation into the corresponding site on the pNZ8048 plasmid. The ligated DNA was then transformed into Lactococcus lactis NZ9000 cells by electroporation method.Verification of cloning was carried out using restriction enzyme digestion and DNA sequencing. Gel electrpophoresis technique also detected the expression of the recombinant protease protein. The successfulcloning and expression of the eprA1 gene into L. lactis can be developed as a useful and safe system to control A. hydrophila infections in fish.