Aziz Mohammad Azhar, Sikriwal Deepa, Singh Samer, Jarugula Sridhar, Kumar P Anand, Bhatnagar Rakesh
Center for Biotechnology, Jawaharlal Nehru University, New Delhi, India.
FASEB J. 2005 Sep;19(11):1501-3. doi: 10.1096/fj.04-3215fje. Epub 2005 Jul 19.
Vaccination against anthrax is the most important strategy to combat the disease. This study describes a generation of edible transgenic crop expressing, functional protective antigen (PA). In vitro studies showed that the plant-expressed antigen is qualitatively similar to recombinant PA. Immunization studies in mouse animal models indicated the generation of PA-specific neutralizing antibodies and stressed the need for improving expression levels to generate higher antibody titers. Genetic engineering of a plant organelle offers immense scope for increasing levels of antigen expression. An AT-rich PA gene (pagA) coding for the 83-kDa PA molecule was thus cloned and expressed in tobacco chloroplasts. Biolistics was used for the transformation of a chloroplast genome under a set of optimized conditions. The expression of the pagA gene with 69% AT content was highly favored by an AT-rich chloroplast genome. A multifold expression level of functional PA was obtained as compared with the nuclear transgenic tobacco plants. This report describes for the first time a comprehensive study on generating transgenic plants expressing PA, which may serve as a source of an edible vaccine against anthrax. Two important achievements of expressing PA in an edible crop and use of chloroplast technology to enhance the expression levels are discussed here.
炭疽疫苗接种是对抗该疾病的最重要策略。本研究描述了一代表达功能性保护性抗原（PA）的可食用转基因作物。体外研究表明，植物表达的抗原在质量上与重组PA相似。在小鼠动物模型中的免疫研究表明产生了PA特异性中和抗体，并强调需要提高表达水平以产生更高的抗体滴度。植物细胞器的基因工程为提高抗原表达水平提供了广阔空间。因此，克隆了编码83 kDa PA分子的富含AT的PA基因（pagA）并在烟草叶绿体中表达。在一组优化条件下，使用生物弹道法转化叶绿体基因组。富含AT的叶绿体基因组非常有利于表达AT含量为69%的pagA基因。与核转基因烟草植物相比，获得了功能性PA的多重表达水平。本报告首次描述了关于生成表达PA的转基因植物的全面研究，这些植物可作为抗炭疽可食用疫苗的来源。本文讨论了在可食用作物中表达PA以及利用叶绿体技术提高表达水平的两项重要成果。
