Fish source Lactobacillus plantarum expressing IPNV VP2-VP3 recombinant protein and its oral immunization program

Comparison of the expression of fish-derived lactic acid bacteria expression system in oral vaccines was made under different immune process, to determine fish source Lactobacillus expression system immune program for immunization of juvenile rainbow trout. In this study, we constructed L. plantarum L1212 in recombinant protein expression IPNV VP2-VP3, then the recombinant strain pPG612-VP2-VP3 / L1212 was coated with pellet feed and immune Oncorhynchus mykiss juvenile fish. Immunization program was divided into continuous immunization group: the group that is immune for a single day after immunization for 1 day; the group that strengthens the immune 1 times after 4 days of continuous immunization 32 d and the group that strengthens the immune 1 times after interval immunization 32 d. After immunization, tail artery blood collection is carried out, and the serum antibody titers are measured by indirect ELISA. After immunization for 66 days, IPNV is injected abdominal cavity and the relative immune protection rates were calculated for each group. To determine the pellet feed in accordance with 1 mL/g ratio and 108 CFU/mL recombinant bacteria pPG612-VP2-VP3 / L1212 and 2.5% sodium alginate mixed 20 °C drying preparation of oral vaccine; the titer and challenge protection rate of serum antibody in interval immunization group were significantly higher than those of other groups, and the serum antibody titer and challenge protection rate in the twice-immunization group were significantly higher than those of the group immunized once. The immunization program and the immunoprotection rate of the juvenile O. mykiss were collected by the recombinant bacteria. The immunization program was superior to the immunization program for continuous immunization and protected the invasion of IPNV.