Vaccine Of Serogroup B Neisseria Meningitides Surface Protein A And Its Immunoprotection In Mice

Objective: To explore the specific humoral and cellular immune responseinduced by the prokaryotic recombinant protein NspA,and evaluateimmunoprotection of the recombinant NspA in mice, and provide some experimentalbasis for the serogroup B Neisseria meningitides vaccine.Method: The prokaryotic recombinant plasmid pGEX-6P-1/NspA wasconstructed, and identified by PCR and the double-enzymes digestion, and finallytransformed into E.coli BL21to express the recombinant protein.The humoral andcellular immune responses induced by the recombinant protein were detected infemale BALB/c mice; the bactericidal titers in vitro were calculated by mixing theimmune serum, MC58and complement of rabbit.The animal model was built inorder to evaluate immunoprotection of the recombinant NspA in mice.Results: The recombinant NspA proteins were expressed in supernatant. Thelevels of NspA-specific sIgA in murine genital tract and kinds of IgG in serumshowed upward trend along with the weeks post inoculation in rNspA group. Thetiters of sIgA,IgG,IgG1,IgG2a and IgG2b at the week6,were1:2800,1:8800,1:7000,1:5120and1:2800respectively,which were significantly higher than the control group;and the ratio of IgG2a/IgG1was less than1.The levels of INF-γand IL-4were300.0pg/mL and229.0pg/mL.The stimulation index(1.61) of the splenic lymphocytewas significantly higher than those of the GST and PBS controls (P<0.05). Thebactericidal titers of50%meningococcal strain MC58in vitro was1:64,the ratio ofimmunoprotection of the recombinant NspA in mice was100%in72hours.Conclusion:1. The prokaryotic recombinant plasmid pGEX-6P-1/NspA was constructed successfully.2. Both humoral and cellular immunologic responses, especially for atendentious Th2humoral immunological response,could be induced by therecombinant protein NspA in BALB/c mice, and the recombinant NspA could inducehigher level of mucosal immune response in the gentital tract mucosa of mice.3.The recombinant NspA showed strong immunoprotection for the mice infectedby the serogroup B Neisseria meningitides,the serum from the vaccinated micepossessed a definite bactericidal effect in vitro.