α-甘露糖肽作为佐剂对恶性疟原虫多表位蛋白疫苗M.RCAg-1免疫原性的影响

Effect of α-mannatide as an adjuvant on immunogenicity of M.RCAg-1,a multiepitope protein vaccine against Plasmodium falciparum

目的探讨α-甘露糖肽(α-mannatide)作为佐剂对恶性疟原虫多表位蛋白疫苗M.RCAg-1免疫原性的影响。方法将小鼠随机分为4组:疫苗组(M.RCAg-1)、疫苗佐剂组(M.RCAg-1+α-mannatide)、佐剂对照组(α-mannatide)、弗氏佐剂对照组(M.RCAg-1+Freund’s),分别于第0、14、28天经背部皮下免疫小鼠,0.1 ml/只。采用ELISA法检测3次免疫后小鼠血清Ig G抗体水平、抗体亚型以及血清抗体对单表位的识别,间接免疫荧光反应(IFA)检测抗体对恶性疟原虫天然蛋白的识别,ELISPOT检测其细胞因子的分泌水平。结果 3次免疫后,疫苗佐剂组GMT明显高于疫苗组(P<0.05);疫苗佐剂组GMT与弗氏佐剂对照组持平(P>0.05)。疫苗佐剂组产生的高水平Ig G主要以Ig G1为主。疫苗佐剂组抗体对单表位和天然虫体的识别效果显著。免疫小鼠各表位和蛋白诱发分泌IL-4的特异性淋巴细胞克隆数高于分泌IFNγ的特异性淋巴细胞克隆数(P<0.05)。结论α-mannatide作为恶性疟原虫多表位蛋白疫苗M.RCAg-1的佐剂能诱导其产生高水平的体液免疫和细胞免疫应答,具有一定的抗疟原虫感染保护作用。

Objective To investigate the effect of α-mannatide as an adjuvant on immunogenicity of M. RCAg-1, a multi- epitope protein vaccine against Plasmodiumfalciparum. Methods Mice were randomly divided into four groups, and im- munized s.c. with M. RCAg-1, M. RCAg-1 ＋ α-mannatide, α-mannatide and M. RCAg-1 ＋ Freund＇s adjuvant respectively on days 0, 14 and 28, 0. 1 ml for each. The serum IgG level, antibody subtype and recognition of single epitopes by serum antibody were determined by ELISA after the third immunization, while the recognition of natural P. fcdciparum protein with antibody by IFA, and the secretion level of cytokines by ELISPOT. Results After the third immunization, the GMT in M. RCAg-1 ＋ α-mannatide group was significantly higher than that in M. RCAg-1 group （P 〈 0. 05）, while was equivalent to that in M. RCAg-1 ＋ Freund＇s adjuvant group （P 〉 0. 05）. The high titer IgGs induced in M. RCAg-1 ＋ α-mannatide group were mainly IgG1. The antibodies in M. RCAg-1 ＋ α-mannatide group recognized single epitopes and natural P. falciparum significantly. The number of specific lymphocyte clones secreting IL-4 induced by various epitopes and proteins of immunized mice was larger than that secreting interferon γ （P 〈 0. 05）. Conclusion As an adjuvant of M. RCAg-1, α-mannatide induced high humoral and cellular immune responses and showed a certain protective effect against plasmodium infection.