Ability of inducing immune response of the inactivated Nervous Necrosis Virus (NNV), E. coIi BL21/NNV expression of T4 gene, encoding NNV antigen and T4 gene recombinant protein, encoding NNV antigen in rabbit and grouper fry was evaluated. The studied result indicated that: In rabbit serum, by using an in vitro assay system, neutralized antibody reached the highest level at the days: 35th - 45th after immunization. The level of inducing immune response of the inactivated NNV and E. coli BL21/NNV was equal, neutralized antibody diluting serum reached 1:800 - 1:1600 at the days: 35th - 45th. Until the day 60th, this concentration reduced to 1:400. In the rabbit group vaccinated with T4 recombinant protein, level of immune response was lower, neutralized antibody with diluting serum concentration reached 1:200 and 1:100 at the days: 35th - 45th. By using an in vivo assay system, the diluting serum concentrations having neutralized antibody in the day 60th were 1:100, 1:50, 1:10, respectively to the vaccinated groups with the inactivated NNV, E. coli BL21/NNV and T4 gene recombinant protein. For grouper fry, neutralized antibody was still found at the day 90th with 3 experimental groups (although gene encoding antigen of NNV was identified in the experimental fish group with E. coli BL21/NNV and T4 gene recombinant protein). The highest level of creating immune response was at the days: 30th-45th. Of which, the specific immune response in fish vaccinated with inactivated NNV was higher than that of T4 gene recombinant antigen and similar with E. coIi BL21/NNV, expression of T4 gene, encoding NNV antigen. The creation of NNV neutralized antigen in grouper fry until the day 90th was a basis for producing vaccine against NNV disease in marine fish culture.