Walter Reed Army Institute of Research, Military Malaria Research Program, Malaria Vaccine Branch, Silver Spring, MD, USA.
Biotechnol J. 2012 Jan;7(1):133-47. doi: 10.1002/biot.201100331. Epub 2011 Dec 28.
Inclusion of affinity tags has greatly facilitated process development for protein antigens, primarily for their recovery from complex mixtures. Although generally viewed as supportive of product development, affinity tags may have unintended consequences on protein solubility, susceptibility to aggregation, and immunogenicity. Merozoite surface protein 1 (MSP1), an erythrocytic stage protein of Plasmodium falciparum and a candidate malaria vaccine, was used to evaluate the impact of a metal ion affinity-tag on both protein structure and the induction of immunity. To this end, codon harmonized gene sequences from the P. falciparum MSP1(42) of FVO and 3D7 parasites were cloned and purified with and without a histidine (His) tag. We report on the influence of His-affinity tags on protein expression levels, solubility, secondary structure, thermal denaturation, aggregation and the impact on humoral and cellular immune responses in mice. While the overall immunogenicity induced by His-tagged MSP1(42) proteins is greater, the fine specificity of the humoral and cellular immune responses is altered relative to anti-parasitic antibody activity and the breadth of T-cell responses. Thus, the usefulness of protein tags may be outweighed by their potential impact on structure and function, stressing the need for caution in their use. See accompanying commentary by Randolph DOI: 10.1002/biot.201100459.
亲和标签的加入极大地促进了蛋白抗原的工艺开发，主要用于从复杂混合物中回收它们。尽管亲和标签通常被认为对产品开发有支持作用，但它们可能会对蛋白的溶解度、聚集倾向和免疫原性产生意想不到的影响。裂殖子表面蛋白 1（MSP1）是恶性疟原虫红细胞阶段的一种蛋白，也是候选疟疾疫苗，被用来评估金属离子亲和标签对蛋白结构和免疫诱导的影响。为此，从恶性疟原虫 FVO 和 3D7 寄生虫的 MSP1（42）克隆并纯化了密码子协调的基因序列，有和没有组氨酸（His）标签。我们报告了 His-亲和标签对蛋白表达水平、溶解度、二级结构、热变性、聚集以及对小鼠体液和细胞免疫应答的影响。虽然 His 标记的 MSP1（42）蛋白诱导的总体免疫原性更高，但体液和细胞免疫应答的精细特异性相对于抗寄生虫抗体活性和 T 细胞反应的广度发生了改变。因此，蛋白标签的有用性可能被其对结构和功能的潜在影响所抵消，这强调了在使用它们时需要谨慎。请参阅伴随的评论文章，DOI：10.1002/biot.201100459。
