Cloning of the IPNV VP2 gene into pNZ8150/Lactococcus lactis expression system: A preliminary phase for the development of IPN vaccines for fish

Infectious pancreatic necrosis virus (IPNV) is one of the major worldwide leading causes of losses among different fish species, especially in salmonidae. In order to develop a vaccine (First stage), the VP2 gene from an Iranian IPNV isolate was amplified using polymerase chain reaction (PCR), inserted between SpeI and ScaI restriction sites of pNZ8150 expression vector under the control of NICE promoter, and transformed into electrocompetent Lactococcus lactis cells using electroporation method regarding production of a recombinant live vector vaccine in fish. The transformed L. lactis cells containing the highest copy of the recombinant plasmid, pNZVP2, were selected using high antibiotic concentration (100 μg/mL of chloramphenicol). These cells are expected to express high level of VP2 protein and consequently will be the best candidates for vaccine formulation. Restriction enzyme digestion using SpeI, colony PCR using gene specific primers and boiling method, and DNA sequencing confirmed construction of the recombinant expression vector, pNZVP2. The present research will pave the way for expression and oral delivery of not only IPNV antigens, but also, any other infectious agents via pNZ8150/L. lactis expression system, potentially as a novel platform for the development of oral delivery vaccines in fish.