Human Coronaviruses as Multigene Mucosal Vaccine Vectors for HIV

描述（由申请人提供）：一种有效的HIV-1疫苗方法不仅需要在全身和粘膜部位诱导广泛反应性中和抗体和细胞免疫反应，而且疫苗还必须在安全性、制造成本、接种次数和给药方便性方面能够可行地分发到世界上最需要它的部分地区。普通感冒人类冠状病毒（HCoV） OC43作为艾滋病毒的疫苗载体很有吸引力，最近冠状病毒反向遗传学的突破使其作为疫苗载体的开发成为可能。冠状病毒基因组是自然界中最大的RNA基因组（约30kb），包含多个对病毒复制不必需的基因，理论上允许将多个异源基因插入单个病毒中，其包装能力远远大于大多数其他载体系统。由于HCoV OC43仅引起轻度上呼吸道感染，因此预计作为疫苗载体相对安全，允许使用具有复制能力的病毒在粘膜表面呈递异源抗原进行多轮载体复制，就像减毒活疫苗一样。冠状病毒基因组也可以经过改造，与自然循环的病毒株重组后产生死病毒。我们最近完成了HCoV OC43的反向遗传系统的开发，这使得开发基于HCoV OC43的疫苗载体在技术上是可行的。在这个分阶段的创新R21/R33项目中，我们建议将HCoV OC43基因组作为SIV的多异源基因表达载体，我们将使用SIVsmE660/猕猴模型对其进行评估。在R21概念验证阶段，我们将：(i)设计HCoV OC43，从载体基因组的不同区域表达SIVsmH4基质/衣壳（MA/CA）基因，（ii）评估表达MA/CA的HCoV OC43载体在小鼠体内的全身、粘膜和细胞免疫原性。在R33阶段，我们将：(i)表征HCoV OC43在猕猴中的感染性，（ii）设计并验证重组抗性HCoV OC43结构，以表达多达四种SIVsmH4蛋白- gag， Env， Nef和Vif，以及（iii）用多基因HCoV OC43载体接种猕猴，并通过SIVsm E660粘膜攻击评估疫苗效果。该项目将首次对普通感冒人类冠状病毒作为艾滋病毒活粘膜疫苗载体的潜在用途进行批判性评估。公共卫生相关性：在拟议的研究中，我们将开发人类冠状病毒，它导致约三分之一的普通感冒，作为传递HIV抗原的疫苗载体。冠状病毒载体作为艾滋病毒疫苗有几个潜在的吸引人的特点，如安全性、制造简单、能够在艾滋病毒传播部位诱导免疫反应，以及能够在有限的接种次数下诱导免疫反应。我们将利用SIV/猕猴模型评估冠状病毒作为HIV疫苗载体的潜在用途。

DESCRIPTION (provided by applicant): An effective HIV-1 vaccine approach not only will need to induce broadly reactive neutralizing antibody and cellular immune responses at systemic and mucosal sites, but the vaccine also will have to be feasible for distribution to parts of the world that need it most in terms of safety, manufacturing cost, number of inoculations, and ease of administration. The common cold human coronavirus (HCoV) OC43 is attractive as a vaccine vector for HIV, and recent breakthroughs in coronavirus reverse genetics have now made it feasible for their exploitation as vaccine vectors. Coronavirus genomes are the largest RNA genomes in nature (~30kb), and contain multiple genes that are not essential for viral replication, theoretically allowing the insertion of multiple heterologous genes into a single virus with a packaging capacity much larger than most other vector systems. Because HCoV OC43 causes only a mild upper respiratory tract infection, it is anticipated to be relatively safe as a vaccine vector, allowing for replication competent viruses to be used to present heterologous antigen at mucosal surfaces for multiple rounds of vector replication, much like a live attenuated vaccine. Coronavirus genomes also can be engineered such that recombination with naturally circulating strains yields a dead virus. We recently completed the development of a reverse genetics system for HCoV OC43, which now makes it technically feasible to develop a HCoV OC43-based vaccine vector. In this phased innovation R21/R33 project we propose to engineer the HCoV OC43 genome as a multiple heterologous gene expression vector for SIV, which we will assess using the SIVsmE660/macaque model. In the R21 proof-of-concept phase we will: (i) engineer HCoV OC43 to express the SIVsmH4 matrix/capsid (MA/CA) gene from different regions of the vector genome, and (ii) evaluate the systemic, mucosal, and cellular immunogenicity of MA/CA-expressing HCoV OC43 vectors in mice. In the R33 phase we will: (i) characterize infectivity of HCoV OC43 in macaques, (ii) engineer and validate a recombination-resistant HCoV OC43 construct to express up to four SIVsmH4 proteins-Gag, Env, Nef and Vif, and (iii) vaccinate macaques with the multigene HCoV OC43 vector and assess vaccine efficacy by mucosal challenge with SIVsm E660. This project will provide the first critical evaluation of the potential use of common cold human coronaviruses as live mucosal vaccine vectors for HIV. PUBLIC HEALTH RELEVANCE: In the proposed study we will develop human coronaviruses, which cause about one- third of all common colds, as vaccine vectors to deliver HIV antigens. There are several potential attractive features of coronavirus vectors as vaccines for HIV, such as safety, simplicity in manufacturing, the ability to induce immune responses in sites of HIV transmission, and the ability to induce immune responses with a limited number of inoculations. We will evaluate the potential use of coronaviruses as HIV vaccine vectors using the SIV/macaque model.