Alga-Produced Cholera Toxin-Pfs25 Fusion Proteins as Oral Vaccines
Alga-Produced Cholera Toxin-Pfs25 Fusion Proteins as Oral Vaccines
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DOI：
10.1128/aem.00714-13
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发表时间：
2013-07-01
影响因子：
4.4
通讯作者：
Mayfield, Stephen
中科院分区：
文献类型：
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作者：
Gregory, James A.;Topol, Aaron B.;Mayfield, Stephen
传染病对贫困地区的影响不成比例，是发展中国家儿童死亡的最大原因。在这些国家使用实用、低成本的疫苗对于减少疾病负担和随之而来的贫困至关重要。藻类是一种有希望的低成本系统，用于生产可以口服递送的疫苗，从而避免昂贵的提纯和注射递送。我们利用真核生物莱茵衣藻的叶绿体生产恶性疟原虫表面蛋白(Pfs25)与霍乱毒素β亚基(CtxB)融合的嵌合蛋白，以研究以藻类为基础的全细胞口服疫苗。Pfs25是一种很有前途的疟疾传播阻断疫苗候选，由于其结构复杂的表皮生长因子样域的串联重复序列，在传统的重组系统中很难生产出来。霍乱全毒素的非催化CtxB结构域组装成五聚体结构，通过与肠上皮细胞上的GM1神经节苷脂受体结合而起到粘膜佐剂的作用。我们证明了CtxB-Pfs25在藻类叶绿体中以可溶的、正确折叠的和功能蛋白的形式积累，并且在常温下在冷冻干燥的藻细胞中是稳定的。在小鼠中，用产生CtxB-Pfs25的冻干藻类口服疫苗可产生CtxB特异性血清抗体以及CtxB和Pfs25特异性分泌型IgA抗体。这些数据表明，藻类是一种很有前途的疫苗抗原生产和口服递送系统，但作为一种口服佐剂，CtxB最适合于利用这一策略诱导针对入侵粘膜表面的病原体的疫苗抗原的分泌型IgA抗体。
Infectious diseases disproportionately affect indigent regions and are the greatest cause of childhood mortality in developing countries. Practical, low-cost vaccines for use in these countries are paramount to reducing disease burdens and concomitant poverty. Algae are a promising low-cost system for producing vaccines that can be orally delivered, thereby avoiding expensive purification and injectable delivery. We engineered the chloroplast of the eukaryotic alga Chlamydomonas reinhardtii to produce a chimeric protein consisting of the 25-kDa Plasmodium falciparum surface protein (Pfs25) fused to the beta subunit of the cholera toxin (CtxB) to investigate an alga-based whole-cell oral vaccine. Pfs25 is a promising malaria transmission-blocking vaccine candidate that has been difficult to produce in traditional recombinant systems due to its structurally complex tandem repeats of epidermal growth factor-like domains. The noncatalytic CtxB domain of the cholera holotoxin assembles into a pentameric structure and acts as a mucosal adjuvant by binding GM1 ganglioside receptors on gut epithelial cells. We demonstrate that CtxB-Pfs25 accumulates as a soluble, properly folded and functional protein within algal chloroplasts, and it is stable in freeze-dried alga cells at ambient temperatures. In mice, oral vaccination using freeze-dried algae that produce CtxB-Pfs25 elicited CtxB-specific serum IgG antibodies and both CtxB- and Pfs25-specific secretory IgA antibodies. These data suggest that algae are a promising system for production and oral delivery of vaccine antigens, but as an orally delivered adjuvant, CtxB is best suited for eliciting secretory IgA antibodies for vaccine antigens against pathogens that invade mucosal surfaces using this strategy.