Virus-Like Particle Vaccine for SARS-CoV

描述(申请人提供)：严重急性呼吸系统综合症(SARS)大流行，由致病冠状病毒(CoV)从动物宿主中重新出现而引起，是一个严重的威胁。通过接种疫苗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被称为病毒样颗粒(VLP)的空衣壳。VLP在免疫学上类似于天然病毒粒子。作为候选疫苗，VLP具有非复制性和非致病性，以及以颗粒状和多聚体形式呈现宿主保护性表位的优势。我们通过在杆状病毒/昆虫细胞系统中表达S蛋白(S)、膜蛋白(M)和小囊膜蛋白(E)来产生SARS-CoV VLP，并证明VLP在兔体内具有免疫原性。我们现在建议：(1)从昆虫细胞培养中制备高纯度的SARS-CoV M+E和M+E+S VLP；(2)鉴定SARS-CoV VLP疫苗在BALB/c小鼠中的免疫原性；(3)确定VLP疫苗保护SARS-CoV活病毒攻击BALB/c小鼠和雪貂的效力。最近的研究表明，S体内氨基酸的变化可以介导对S假型病毒中和能力的增强和进入的增强。冠状病毒保守的C末端含有有助于增强的表位。因此，我们的最终特异性目标(4)是确定小鼠抗血清对SARS冠状病毒株VLP和人类冠状病毒OC43和229E的交叉中和/增强能力。拟议研究的成功实施将为未来以VLP为基础的SARS-CoV疫苗的临床试验提供垫脚石。

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.