Immunocompetence And Immunoprotection Of A Dna Vaccine NMB0315 Against Neisseria Meningitidis Serogroup B In Mice

[Objective] To construct NMB0315 eukaryotic expression recombinant vector, detect specific humoral and cellular immune response induced by the recombint DNA vaccine inoculated intramuscularly or abdominally in female BALB/c mice, evaluate the immunocompetence and immunoprotection of the vaccine, so as to provide experimental basis for the development of a novel nucleic acid vaccine against N.meningitides serogroup B. [Methods] The whole NMB0315 gene was amplified by PCR from the standard strains MC58 genomic DNA, cloned into a plasmid pc DNA3.1(+), identified by double digestion of the recombinant plasmid with restriction enzymes Bam H I and Xho I and sequencing. The recombinant vector pc DNA3.1(+) /NMB0315 was transfected into eukaryotic COS-7 cells and RAW264.7 cells, the expressed NMB0315 protein was identified by immunocytochemical method and Western blot respectively. The levels of specific humoral and cellular immune response were detected after inoculating intramuscularly or abdominally in female BALB/c mice with the recombinant plasmid. The immune protective effect was investigated with the DNA vaccine and the bactericidal titer of the immune serum was determined by serum bactericidal assay(SBA) in vitro.[Results] The recombinant pc DNA3.1(+)/NMB0315 was effectively transcripted and expressed in eukaryotic cells and the specific humoral and cellular immune responses were induced in the inoculated mice.In the recombinant pc DNA3.1(+)/NMB0315 group,the levels of serum Ig G, Ig G1, Ig G2 a, Ig G2 b and Ig G3 and genital tract s Ig A were significantly higher than in controls( P<0.001). The levels of IL-4, IFN-γ andstimulation index in the culture supernatant of the spleen lymphocytes of the vaccine group were higher than those of the control groups(P<0.05). The ratios of serum Ig G2a/Ig G1 in the DNA vaccine group were less than 1. The bactericidal titer of the pc DNA3.1(+)/NMB0315+Cp G group reached 1:128 following three immunizations, the protection rate of the vaccine group was 70% against the N. meningitidis strain MC58. [Conclusion]1. The recombinant pc DNA3.1(+) /NMB0315 vaccine could induce high levels of humoral immunity and cellular immunity, especially mucosal immune responses.2. The recombinant pc DNA3.1(+) /NMB0315 vaccine showed effective immunoprotection against N.meningitidis serogroup B in BALB/c mice, the immune serum showed strong bactericidal activity in vitro.