Virus-Like Particle Vaccine for SARS-CoV

描述（由申请人提供）：严重急性呼吸系统综合症（SARS）大流行是一种严重的威胁，由病原体冠状病毒（CoV）从动物宿主重新出现引起。通过疫苗接种诱导保护性抗体已被证明是对高传染性病毒病原体最有效的干预措施。病毒的衣壳蛋白通常自组装成称为病毒样颗粒（vlp）的空衣壳。VLPs在免疫学上类似于天然病毒粒子。作为候选疫苗，VLPs具有非复制性和非致病性的优势，并且以颗粒和多聚体形式呈现宿主保护性表位。我们通过杆状病毒/昆虫细胞系统中刺突蛋白(S)、膜蛋白(M)和小包膜蛋白(E)的表达生成了SARS-CoV VLP，并证明VLP在家兔中具有免疫原性。我们现在建议：(1)开发从昆虫细胞培养中生产高纯度SARS-CoV M+E和M+E+S VLP的有效方法；(2)表征SARS-CoV VLP疫苗在BALB/c小鼠中的免疫原性；(3)确定VLP疫苗对感染SARS-CoV的BALB/c小鼠和雪貂的保护效力。最近的研究表明，S中氨基酸的变化可以介导对S伪病毒侵入的中和和增强抗性。冠状病毒保守的C端含有有助于增强的表位。因此，我们最终的具体目的(4)是确定小鼠培养的抗血清对SARS-CoV毒株和人类冠状病毒OC43和229E的VLPs的交叉中和/增强能力。拟议研究的成功实施将为未来基于vlp的sars冠状病毒疫苗的临床试验奠定基础。

DESCRIPTION (provided by applicant): A Severe Acute Respiratory Syndrome (SARS) pandemic, caused by re-emergence of the causative coronavirus (CoV) from an animal reservoir, is a serious threat. Induction of protective antibody by vaccination has proven the most effective intervention for highly contagious viral pathogens. The capsid proteins of viruses typically self-assemble into empty capsids known as virus-like particles (VLPs). VLPs resemble native virions immunologically. As vaccine candidates, VLPs have the advantage of being non-replicating and non-pathogenic, and of presenting host protective epitopes in a particulate and multimeric form. We have generated SARS-CoV VLPs by expression of the spike (S), membrane (M) and small envelope (E) proteins in the baculovirus/insect cell system and shown that VLP are immunogenic in rabbits. We now propose: (1) to develop efficient methods for production of highly purified SARS-CoV M+E and M+E+S VLPs from insect cell cultures, (2) to characterize the immunogenicity of SARS-CoV VLP vaccines in BALB/c mice; and (3) to determine the potency of a VLP vaccine to protect BALB/c mice and ferrets challenged with live SARS-CoV. Recent studies have shown that amino acids changes in S can mediate increased resistance to neutralization and enhancement of S pseudotype virus entry. The conserved C terminus of coronaviruses contains epitopes that contribute to enhancement. Thus, our final specific aim (4) is to determine the cross neutralizing/enhancing capacity of antisera raised in mice against VLPs of SARS-CoV strains and the human coronaviruses, OC43 and 229E. The successful implementation of the proposed studies would provide a stepping-stone toward future clinical trials with a VLP-based SARS-CoV vaccine.