Evaluation of Flavivirus Live Attenuated Vaccine Recombination Potential

说明(申请人提供)：黄病毒是人类发病和死亡的重要原因，这些病原体通过节肢动物传播，每年导致数千人死亡。传统的病媒控制一直是防治蚊媒疾病的主要战略；然而，蚊媒种群的扩大，加上缺乏抗病毒疗法，强调了疫苗开发的迫切需要。黄热病(YF)17D疫苗被认为是有史以来最安全和最有效的疫苗之一，因此成为开发异源黄病毒减毒活疫苗的平台。由于这些减毒病毒具有复制能力，可在脊椎动物中引起病毒血症，并能够轻微感染节肢动物，因此建议谨慎使用它们，因为疫苗和野生型毒株之间存在理论上的重组潜力。这项建议的目的是评估这些基于17D的病毒的安全性，特别是关于重组的可能性。我们假设，由于体内疫苗复制动力学的减弱和产生有效重组所需的严格的分子约束，减毒黄病毒活疫苗重组可能是一个极其低效的过程。实验旨在评估带有序列标签的17D病毒在细胞培养中进行重组的可能性，并评估在蚊子媒介中发生重组的可能性。拟议的研究对黄病毒流行地区疫苗的开发和公共卫生的改善具有非常重要的意义，因为它们通过评估黄病毒疫苗重组体出现的可能性直接解决了这一主要安全问题。 公共卫生相关性：项目说明：蚊媒病毒是人类疾病的主要原因，节肢动物传播这些病原体每年导致数千人死亡。减毒活疫苗是控制这些病原体的一种有吸引力的策略；然而，人们对这些疫苗病毒在自然界中进化的可能性提出了担忧。这项提案中包含的研究对蚊媒病毒传播地区疫苗的开发和改善公共卫生具有非常重要的意义，因为它们直接解决了这一安全问题。

DESCRIPTION (provided by applicant): Flaviviruses are a significant cause of human morbidity and mortality with arthropod-borne transmission of these agents resulting in thousands of deaths per annum. Classical vector control has been the primary strategy to combat mosquito-borne diseases; however, population expansion of mosquito vectors, coupled with a lack of anti-viral therapeutics serves to emphasize the urgent need for vaccine development. The yellow fever (YF) 17D vaccine has been regarded as one of the safest and most efficacious vaccines ever developed and as such has become a platform for the development of live attenuated flavivirus vaccines for heterologous flaviviruses. Since these attenuated viruses are replication competent, inducing viremia in vertebrates and capable of mild arthropod infectivity caution has been recommended in their use due to the theoretical potential for recombination between vaccine and wild type strains. The purpose of this proposal is to evaluate the safety of these 17D based viruses with specific regard to the potential for recombination. We hypothesize that live attenuated flavivirus vaccine recombination is likely an extremely inefficient process due to attenuated in vivo vaccine replication kinetics and stringent molecular constraints required for generation of a viable recombinant. Experiments have been designed to evaluate the potential for sequence tagged 17D viruses to undergo recombination in cell culture and to assess the potential for recombination to occur in the mosquito vector. The proposed studies are highly significant to the development of vaccines and improvement of public health, in flavivirus endemic regions, because they directly address this major safety concern, by evaluating the potential for emergence of flavivirus vaccine recombinants. PUBLIC HEALTH RELEVANCE: Project Narrative: Mosquito-borne viruses are a major cause of human illness with arthropod-borne transmission of these agents resulting in thousands of deaths annually. Live attenuated vaccines are an attractive strategy for control of these agents; however concerns have been raised about the potential for these vaccine viruses to evolve in nature. The studies contained in this proposal are highly significant to the development of vaccines and improvement of public health in regions of mosquito-borne virus transmission, because they directly address this safety concern.