Puckette Michael, Clark Benjamin A, Barrera José, Neilan John G, Rasmussen Max V
U.S. Department of Homeland Security Science and Technology Directorate, Plum Island Animal Disease Center, P.O. Box 848, Greenport, NY 11944, USA.
Oak Ridge Institute for Science and Education, Plum Island Animal Disease Center Research Participation Program, P.O. Box 848, Greenport, NY 11944, USA.
Vaccines (Basel). 2023 Feb 7;11(2):386. doi: 10.3390/vaccines11020386.
We evaluated four DNA vaccine candidates for their ability to produce virus-like particles (VLPs) and elicit a protective immune response against Foot-and-mouth disease virus (FMDV) in cattle. Two traditional DNA plasmids and two DNA minicircle constructs were evaluated. Both the pTarget O1P1-3C plasmid and O1P1-3C minicircle encoded a wild-type FMDV 3C protease to process the P1-2A polypeptide, whereas the O1P1-HIV-3C minicircle used an HIV-1 ribosomal frameshift to down-regulate expression of a mutant 3C protease. A modified pTarget plasmid with a reduced backbone size, mpTarget O1P1-3C, used a 3C protease containing two mutations reported to enhance expression. All constructs produced mature FMDV P1 cleavage products in transfected cells, as seen by western blot analysis. Three constructs, O1P1-3C minicircles, pTarget O1P1-3C, and mpTarget O1P1-3C plasmids, produced intracellular VLP crystalline arrays detected by electron microscopy. Despite VLP formation in vitro, none of the DNA vaccine candidates elicited protection from clinical disease when administered independently. Administration of pTarget O1P1-3C plasmid enhanced neutralizing antibody titers when used as a priming dose prior to administration of a conditionally licensed adenovirus-vectored FMD vaccine. Further work is needed to develop these DNA plasmid-based constructs into standalone FMD vaccines in cattle.
我们评估了四种DNA疫苗候选物产生病毒样颗粒（VLP）的能力以及引发牛对口蹄疫病毒（FMDV）的保护性免疫反应的能力。对两种传统DNA质粒和两种DNA微环构建体进行了评估。pTarget O1P1 - 3C质粒和O1P1 - 3C微环均编码野生型FMDV 3C蛋白酶以加工P1 - 2A多肽，而O1P1 - HIV - 3C微环利用HIV - 1核糖体移码来下调突变3C蛋白酶的表达。一种具有减小骨架大小的修饰pTarget质粒，mpTarget O1P1 - 3C，使用了一种含有据报道可增强表达的两个突变的3C蛋白酶。如蛋白质印迹分析所见，所有构建体在转染细胞中均产生成熟的FMDV P1切割产物。三种构建体，O1P1 - 3C微环、pTarget O1P1 - 3C和mpTarget O1P1 - 3C质粒，产生了通过电子显微镜检测到的细胞内VLP晶体阵列。尽管在体外形成了VLP，但没有一种DNA疫苗候选物单独给药时能引发对临床疾病的保护作用。当用作有条件许可的腺病毒载体FMD疫苗给药前的初免剂量时，pTarget O1P1 - 3C质粒的给药可提高中和抗体滴度。需要进一步开展工作，将这些基于DNA质粒的构建体开发成牛用的独立FMD疫苗。
