不同免疫途径对chitosan-DNA疫苗诱导CVB3特异性免疫应答的影响及其意义

In vivo delivery approaches influence immune responses induced by chitosan-DNA vaccination

目的 确定新型chitosan DNA疫苗的有效免疫途径。方法 将chitosan pcDNA3 VP1疫分别苗以肌注、口服、滴鼻 3种免疫方式免疫Balb c小鼠 ;以ELISA检测免疫小鼠血清中IgG、IgM、IgA ,评估其特异性体液免疫应答 ;以特异性淋巴细胞增殖反应和CTL活性反映其诱导细胞免疫 ;以 5LD50 致死剂量CVB3攻击免疫小鼠 ,评价不同免疫途径的免疫保护效果。结果 ①在诱导CVB3特异性体液免疫方面 :chitosan pcDNA3 VP1疫苗肌注组诱生了高水平IgM和IgG ,但未能诱生黏膜IgA ;口服免疫组仅诱生低水平的黏膜IgA ,未能诱生特异性IgM和IgG ;滴鼻组可诱生低水平的IgM及高水平的IgG和黏膜IgA。②在诱导CVB3特异性细胞免疫方面 :仅滴鼻组诱导了较高水平的淋巴细胞特异性增殖反应和CTL活性 ;口服组的淋巴细胞增殖活性和CTL活性稍弱 ;肌注组几乎不能诱导特异性细胞免疫应答。③免疫保护作用 :滴鼻组可保护 33.3%小鼠长期存活 ;口服组仅达到 16 .7%的保护率 ;肌注组无保护作用。结论 滴鼻免疫途径可能是chitosan pcDNA3

Objective To characterize the specific immune responses induced by chitosan embedded pcDNA3-VP1 gene vaccine via intramuscular, oral and intranasal routes so as to find an effective immunization approach for this novel chitosan-DNA vaccine.Methods Balb/c mice were immunized with chitosan-pcDNA3-VP1 vaccine containing CVB3 VP1 encoding sequences intramuscularly, orally and intranasally, three times with 50 μg DNA each time, CVB3 specific IgM, IgG and IgA were detected by ELISA to evaluate the humoral immune response induced by chitosan-DNA vaccine and specific lymphoproliferation to VP1 peptide and CTL activity were also examined representing cellular immune responses induced. Finally, mice were challenged with 5LD 50 CVB3 four weeks after the last immunization.Results In terms of CVB3-specific humoral immune responses, intramuscular immunization with chitosan-pcDNA3-VP1 generated high levels of CVB3 specific IgM and IgG but not mucosal IgA; intranasal immunization elicited high levels of both IgG and mucosal IgA while oral immunization induced only low level of mucosal IgA. As to the cellular immune responses induced by chitosan-DNA vaccine, only splenocytes from mice immunized intranasally responsed to VP1 peptide and showed high CTL activity. Cellular immune response induced by oral immunization was a little weaker while those by intramuscular immunization were too low to be detected. 33.3% mice following intranasal immunization with chitosan-pcDNA3-VP1 survived from lethal CVB3 challenge, while the survival rate of oral and intramuscular immunization groups was 16.7% and 0 separately.Conclusion Intranasal delivery of chitosan-pcDNA3-VP1 vaccine could be the most effective administration route to induce stronger immune responses and immunoprotection against CVB3.