Immunocompetence and Immunoprotection of a DNA vaccine NMB0315 against N.meningitidis serogroup B in mice / 中国免疫学杂志

ABSTRACT

Objective:To construct NMB0315 eukaryotic expression recombinant vector ,detect specific humoral and cellular immune response induced by the recombint DNA vaccine intramuscularly 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.meningitidis serogroup B .Methods: The whole NMB0315 gene was amplified by PCR from the standard strains MC 58 genomic DNA,cloned into a plasmid pcDNA3.1(+),identified by double digestion of the recombinant plasmid with restriction enzymes and se -quencing.The recombinant vector pcDNA 3.1 (+)/NMB0315 was transfected into eukaryotic COS-7 cells and RAW264.7 cells, the NMB0315 protein was detected by immunocytochemical method and Western blot respectively .The levels of specific humoral and cellular immune response were detected after inoculating in female BALB /c mice intramuscularly with the recombinant plasmid .The immune protective effect was investigated with the DNA vaccine and the bactericidal titer of the immune serum was deter mined by serum bactericidal assay ( SBA ) in vitro.Results: The recombinant pcDNA3.1 (+)/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 re-combinant pcDNA3.1(+)/NMB0315 group ,the levels of serum IgG,IgG1,IgG2a,IgG2b and IgG3 and genital tract sIgA were significantly higher than in controls ( P<0.001 ) .The stimulation index in the culture supernatant of the spleen lymphocytes of the vaccine group was higher than that of the control group (P<0.05).The ratios of serum IgG2a/IgG1 in the DNA vaccine group were less than 1.The bactericidal titer of the NMB 0315+CpG group reached 1128 following three immunizations , the protection rate of the vaccine group was 70%against the N.meningitidis strain MC58.Conclusion:The NMB0315 nucleic acid vaccine could induce higher levels of humoral immunity and cellular immunity and showed effective protection against N .meningitidis serogroup B , the immune serum had strong bactericidal activity in vitro .