广谱流感疫苗研究领域取得突破性进展

　　

　中山大学有害生物控制与资源利用国家重点实验室曹永长教授课题组与美国Firstline Biopharmaceuticals公司合作，在广谱流感疫苗研究取得突破性进展。

　　流感是一种人畜共患病，目前流感病毒的感染仍然是造成全球人类发病和死亡的重要原因之一。2013年2月开始的H7N9流感给我国禽业和社会经济造成了巨大损失。疫苗免疫是预防流感的主要方法。流感病毒的多宿主和高度变异性，使得现有流感疫苗的有效性受到限制。

   目前使用的疫苗只对特定的病毒株具有保护效力，一旦出现流感病毒新亚型或新毒株，现有疫苗就会失去其保护效力。WHO每年都会针对流感病毒的流行状况预测下一年的流行毒株，将其作为疫苗参考毒株。虽然每年的检测数据有助于选择这些毒株，但它仍旧很难进行准确的预测。当疫苗毒株与流行毒株不匹配时，会导致流感的发病率和死亡率增加，严重时甚至发生流感大流行。因此，研制广谱流感病毒疫苗具有迫切性。

　　近年来，中山大学曹永长教授领导的研究小组与美国Firstline Biopharmaceuticals公司开展合作研究。研究发现，与同属于A型流感病毒的其它所有十七种亚型流感病毒HA蛋白的跨膜区相比较， H3亚型流感病毒HA蛋白的跨膜区具有独特的结构，能形成分子间二硫键，从而使HA蛋白具有高稳定性以及亚型间的交叉免疫力。

    他们进一步将H3亚型HA跨膜区替换到其他亚型流感病毒如H1、H5和H9亚型HA蛋白上，增加了HA蛋白的稳定性。然后用改造过的HA蛋白免疫小鼠，用致死剂量的不同亚型病毒攻击小鼠，这些不同亚型的HA蛋白也获得了针对不同亚型流感病毒的交叉免疫力。令人鼓舞的是，用改造的H5亚型HA蛋白免疫小鼠，可以100%保护小鼠面对H1N1病毒的攻击。该研究成果可以和现有的人用流感疫苗无缝对接，一个具有交叉免疫力的广谱流感疫苗指日可待。

　　该研究成果于2014年4月2日在线发表在著名疫苗专业杂志Vaccine上，中山大学曹永长教授为通讯作者。该研究成果得到了国家自然科学基金—广东联合基金（U1131005）的资助。

原文摘要：

Recombinant influenza H1, H5 and H9 hemagglutinins containing replaced H3 hemagglutinin transmembrane domain showed enhanced heterosubtypic protection in mice.

Influenza A viruses cause annual epidemics and irregular pandemics. A vaccine with heterosubtypic protection (hetero-protection) has been needed. In the present study, various influenza H1, H3, H5, and H9 hemagglutinin (HA) proteins were expressed in insect cells, and then mice were subcutaneously immunized with the expressed HA proteins, and challenged by influenza A viruses (A/Puerto Rico/8/1934 (H1N1) or A/chicken/Guangdong/96 (H9N2)). The results first showed that wild-type H3 hemagglutinin (HA) (H3-WT), but not a transmembrane domain (TM) mutant, had hetero-protection against both H1N1 and H9N2 with survival rates of 17% and 33% respectively, and that wild-type H1 (H1-WT), H5 (H5-WT) and H9 (H9-WT) had no hetero-protection against H1N1 or H9N2 except for H5-WT against H1N1 with a survival rate of 17%. Then the H3-WT TM replaced the TMs of H1-WT, H5-WT and H9-WT to generate recombinant H1-TM, H5-TM and H9-TM respectively, and whether the H3-WT TM-dependent hetero-protection could be transferred to these TM mutants was investigated. The results showed that the H3-WT TM-dependent hetero-protection was transferable. H1-TM against H9N2 and H9-TM against H1N1 were with survival rates of 33% and 17% respectively, and H5-TM against both H1N1 and H9N2 with survival rates of 50% and 17% respectively. Furthermore, higher dosage H5-TM scored 100% hetero-protection against H1N1. These results demonstrated that replacement of the TMs of non-H3 HAs with H3-WT TM could enhance their hetero-protection. These findings would help the development of future influenza vaccines against pandemics such as the recently appeared H7N9 infection.