基于PTC病毒技术的高致病性禽流感病毒应急疫苗研究

Highly pathogenic avian influenza virus (HPAIV) can spread across species isolated from poultry to human directly with high mortality, poses a serious threat to human health. The antiviral resistance of those virus to the main antiviral drugs had been detected recently and the continued sporadic human infection led to an increasing risk of interpersonal transmission，which exacerbated the possibility of avian influenza pandemic. At the same time, HPAIV has been classified as a potential biological warfare agent due to the high mortality rate after human infection. There is no effective strategy for rapid construction of emergency vaccines at present. Recently, a research on new type vaccine based on premature termination codon-harboring (PTC) virus was reported, which provides us a new strategy for rapid live-attenuated vaccine development of HPAIV. During the preliminary work, we jointly established the PTC virus system based on H1N1 virus with collaborating laboratory in Peking university, and verified its effectiveness and safety in the cell line with orthogonal translation system. The gene sequences encoding H5 and H7 subtype protein were synthesized completely, which given the basis to the construction of highly pathogenic avian influenza PTC virus. Based on the novel PTC virus strategy, this project explores the rapid development of HPAIV attenuated vaccine. We aim to obtain a safe and efficient HPAIV PTC vaccine candidate. This project will pave the way for the rapid development of highly pathogenic avian influenza emergency vaccine, and also explore the new strategy for epidemic prevention and control of highly pathogenic avian influenza with frequent reassortment and antigen drift in China.

高致病性禽流感病毒（HPAIV）能够跨越种间隔离从禽类直接传染给人类，感染后致死率高。目前，HPAIV已表现出对一线抗流感药物的耐药趋势，且持续散发疫情导致人际传播风险不断加剧。同时，由于感染后死亡率高，HPAIV已被列为潜在生物战剂。基于PTC（提前终止密码子）病毒的新型疫苗研发策略为应急疫苗快速研发提供了新的思路。前期工作中，我们联合合作实验室基于H1N1流感病毒构建了PTC疫苗系统，在稳转正交翻译系统的细胞系中验证了其有效性及安全性，并对HPAIV H5和H7基因进行了全合成，为高致病性禽流感PTC病毒的构建奠定了基础。本项目基于前沿PTC病毒策略，探索HPAIV减毒疫苗的快速研发技术，最终希望获得安全高效的HPAIV PTC疫苗候选株。本研究的开展，将为高致病性禽流感应急疫苗的快速研发奠定基础，在流感频繁发生基因重配、抗原漂移的背景下，为我国高致病性禽流感疫情应急防控探索新的策略。

高致病性禽流感病毒属于正粘病毒科流感病毒属，其基因组为分节段的负链RNA病毒，能够跨越种间隔离从禽类直接传染给人类，感染后致死率高。目前，HPAIV已表现出对一线抗流感药物的耐药趋势，且持续散发疫情导致人际传播风险不断加剧。基于PTC病毒的新型疫苗研发策略为应急疫苗快速研发提供了新的思路。本课题利用流感反向遗传学技术，基于H7N9和H5N1流行株构建得到全长型和嵌合型高致病性禽流感病毒株、低致病性禽流感病毒株以及假病毒体系。进一步结合PTC技术对特定位点进行突变，拯救获得PTC病毒，优选基于嵌合型H5N1毒株构建的PTC-2作为候选株，并考察了其在小鼠模型中对病毒感染的保护效果。结果表明PTC-2病毒疫苗对H5N1病毒感染具有较好的保护效果。基于嵌合型毒株构建的PTC病毒策略可能更适合于流感病毒应急疫苗研发。

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