鉴定恶性疟原虫 Pf51 蛋白作为一种疟疾疫苗候选抗原，其靶向作用于红内期无性体增殖和传播。
Characterization of Pb51 in Plasmodium berghei as a malaria vaccine candidate targeting both asexual erythrocytic proliferation and transmission.
机构信息
Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, 110001, Liaoning, China.
Laboratory of Surgery, The Affiliated Hospital, Inner Mongolia Medical University, Hohhot, 010050, China.
出版信息
Malar J. 2017 Nov 13;16(1):458. doi: 10.1186/s12936-017-2107-2.
BACKGROUND
A vaccine that targets multiple developmental stages of malaria parasites would be an effective tool for malaria control and elimination.
METHODS
A conserved gene in Plasmodium, the Plasmodium berghei gene (PBANKA_020570) encoding a 51 kDa protein (pb51 gene), was identified through search of the PlasmoDB database using a combination of expression and protein localization criteria. A partial domain of the Pb51 protein was expressed in a prokaryotic expression system (rPb51) and used for immunization in mice. The protein expression profile and localization were studied by Western blot and indirect immunofluorescence assay (IFA), respectively. The inhibitory effect of the anti-rPb51 antibodies on parasite proliferation was evaluated in erythrocytes in vivo. The transmission-blocking activity of the immune sera was determined by in vitro ookinete conversion assay and by direct mosquito feeding assay (DFA).
RESULTS
The rPb51 elicited specific antibodies in mice. Western blot confirmed Pb51 expression in schizonts, gametocytes and ookinetes. IFA showed localization of Pb51 on the outer membranes of schizonts, gametocytes, zygotes, retorts, ookinetes and sporozoites of P. berghei. Mice immunized with the rPb51 protein significantly reduced parasite proliferation and gametocyte conversion in vivo. Moreover, the rPb51 antisera also significantly reduced the in vitro ookinete conversion when added into the ookinete culture medium. In DFA, mice immunized with the rPb51 reduced the prevalence of mosquito infection by 21.3% and oocyst density by 54.8%.
CONCLUSIONS
In P. berghei, P51 was expressed in both asexual erythrocytic and sexual stages and localized on the surface of these stages with the exception of the ring stage. The anti-rPb51 antibodies inhibited both P. berghei proliferation in mice and transmission of the parasite to mosquitoes.
背景
针对疟原虫多个发育阶段的疫苗将是控制和消除疟疾的有效工具。
方法
通过使用表达和蛋白质定位标准的组合，在 PlasmoDB 数据库中搜索，鉴定出疟原虫中的保守基因，即疟原虫伯氏虫基因（PBANKA_020570）编码的 51kDa 蛋白（pb51 基因）。使用原核表达系统（rPb51）表达 Pb51 蛋白的一部分结构域，并用于小鼠免疫。通过 Western blot 和间接免疫荧光测定（IFA）分别研究蛋白质表达谱和定位。通过体内红细胞评估抗 rPb51 抗体对寄生虫增殖的抑制作用。通过体外配子体转化试验和直接蚊虫喂养试验（DFA）确定免疫血清的阻断传播活性。
结果
rPb51 在小鼠中引发特异性抗体。Western blot 证实 Pb51 在裂殖体、配子体和配子体中表达。IFA 显示 Pb51 定位于疟原虫裂殖体、配子体、合子、配子、配子体和孢子体的外膜上。用 rPb51 蛋白免疫的小鼠体内寄生虫增殖和配子体转化明显减少。此外，当添加到配子体培养物中时，rPb51 抗血清还显著降低了体外配子体转化。在 DFA 中，用 rPb51 免疫的小鼠将蚊子感染的流行率降低了 21.3%，卵囊密度降低了 54.8%。
结论
在 P. berghei 中，P51 在无性红细胞期和有性期均有表达，并定位于这些阶段的表面，除了环状期。抗 rPb51 抗体抑制了 P. berghei 在小鼠中的增殖和寄生虫向蚊子的传播。
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