CEA, iBiTecS, SPI, Laboratory of Antibody Engineering for Health, Gif sur Yvette, France.
DNA Cell Biol. 2010 Mar;29(3):121-31. doi: 10.1089/dna.2009.0940.
Prion diseases (e.g., Creutzfeldt-Jakob disease in humans) are always fatal neurodegenerative disorders characterized by conversion of the ubiquitous cellular prion protein (PrP(c)) into a pathological conformer. Immunological strategies are considered as promising prophylactic or therapeutic approaches but, unfortunately, vaccination attempts until now have been very disappointing in wild-type animals because of immune tolerance to self PrP(c). Encouraging results have come from recent experiments carried out through genetic immunization (i.e., injection in mice of cDNA coding for murine prion protein [PrP]) or heterologous protein immunization (i.e., injection in mice of PrP from another species), albeit the levels of autoantibodies in wild-type animals remained generally low. Here we investigated whether combining the potential benefits of these two last approaches, namely using genetic immunization with the cDNA coding for a heterologous PrP, could more efficiently break immune tolerance. Wild-type mice were thus vaccinated with cDNA coding for human PrP(c), fused or unfused to a stimulatory T-cell epitope, using or not using electrotransfer of DNA. After three DNA injections, mice receiving electrotransferred DNA developed a strong immune response, oriented toward the humoral Th2 type, characterized not only by high IgG1 and IgG2a antibody titers against the heterologous human PrP(c), but also, as expected, by significant amounts of autoantibodies recognizing the native conformation of murine PrP(c) expressed on cell membranes as revealed by flow cytometry and immunofluorescence. These results hence open the way for investigation of the possible protective effects of anti-PrP(c) autoantibodies in infected mouse models. More generally, our results suggest that this original immunization strategy could be of value for circumventing tolerance to poorly immunogenic proteins.
朊病毒疾病（例如人类的克雅氏病）是始终致命的神经退行性疾病，其特征在于普遍存在的细胞朊病毒蛋白（PrP(c)）转化为病理性构象。免疫策略被认为是有前途的预防或治疗方法，但不幸的是，迄今为止，在野生型动物中，疫苗接种尝试由于对自身 PrP(c) 的免疫耐受而非常令人失望。最近通过基因免疫（即向小鼠中注射编码鼠朊病毒蛋白[PrP]的 cDNA）或异源蛋白免疫（即向小鼠中注射来自另一种物种的 PrP）进行的实验取得了令人鼓舞的结果，尽管野生型动物中的自身抗体水平通常仍然较低。在这里，我们研究了结合这两种最后方法的潜在益处，即使用编码异源 PrP 的 cDNA 进行基因免疫，是否可以更有效地打破免疫耐受。因此，用编码人 PrP(c) 的 cDNA 对野生型小鼠进行了疫苗接种，该 cDNA 融合或未融合有刺激 T 细胞表位，使用或不使用 DNA 电转移。在进行了三次 DNA 注射后，接受电转移 DNA 的小鼠产生了强烈的免疫反应，偏向于体液 Th2 型，不仅表现出针对异源人 PrP(c)的高 IgG1 和 IgG2a 抗体滴度，而且如预期的那样，还产生了大量的自身抗体，这些抗体可识别细胞膜上表达的天然构象的鼠 PrP(c)，这是通过流式细胞术和免疫荧光法揭示的。这些结果为研究抗-PrP(c)自身抗体在感染小鼠模型中的可能保护作用开辟了道路。更一般地说，我们的结果表明，这种原始免疫策略对于规避对低免疫原性蛋白的耐受可能具有价值。
