Kohl T, Hitzeroth I I, Stewart D, Varsani A, Govan V A, Christensen N D, Williamson A-L, Rybicki E P
Department of Molecular and Cell Biology, University of Cape Town, Rondebosch, Cape Town 7701, South Africa.
Clin Vaccine Immunol. 2006 Aug;13(8):845-53. doi: 10.1128/CVI.00072-06.
The native cottontail rabbit papillomavirus (CRPV) L1 capsid protein gene was expressed transgenically via Agrobacterium tumefaciens transformation and transiently via a tobacco mosaic virus (TMV) vector in Nicotiana spp. L1 protein was detected in concentrated plant extracts at concentrations up to 1.0 mg/kg in transgenic plants and up to 0.4 mg/kg in TMV-infected plants. The protein did not detectably assemble into viruslike particles; however, immunoelectron microscopy showed presumptive pentamer aggregates, and extracted protein reacted with conformation-specific and neutralizing monoclonal antibodies. Rabbits were injected with concentrated protein extract with Freund's incomplete adjuvant. All sera reacted with baculovirus-produced CRPV L1; however, they did not detectably neutralize infectivity in an in vitro assay. Vaccinated rabbits were, however, protected against wart development on subsequent challenge with live virus. This is the first evidence that a plant-derived papillomavirus vaccine is protective in an animal model and is a proof of concept for human papillomavirus vaccines produced in plants.
通过根癌农杆菌转化法在转基因烟草中表达了天然棉尾兔乳头瘤病毒（CRPV）L1衣壳蛋白基因，并通过烟草花叶病毒（TMV）载体在烟草属植物中进行了瞬时表达。在转基因植物的浓缩植物提取物中检测到L1蛋白，浓度高达1.0毫克/千克，在TMV感染的植物中浓度高达0.4毫克/千克。该蛋白未检测到明显组装成病毒样颗粒；然而，免疫电子显微镜显示有假定的五聚体聚集体，并且提取的蛋白与构象特异性和中和性单克隆抗体发生反应。用含有弗氏不完全佐剂的浓缩蛋白提取物注射兔子。所有血清都与杆状病毒产生的CRPV L1发生反应；然而，在体外试验中它们未检测到可中和感染性。然而，接种疫苗的兔子在随后用活病毒攻击时受到保护，不会出现疣。这是植物源乳头瘤病毒疫苗在动物模型中具有保护作用的首个证据，也是植物生产人乳头瘤病毒疫苗概念验证的证据。
