香港大学9日表示，该校李嘉诚医学院研究人员连同海外合作伙伴的一项研究发现，如果两个H1N1流感病毒的表面蛋白（血凝素以及神经氨酸酶）达到活性的微妙平衡，可使病毒变得有能力经飞沫传播。
据介绍，由于流感病毒在雪貂间传播情况与人类最为相似，因此研究选取其作为动物模型。研究人员选择全球多种主要且具代表性的H1N1流感病毒放于雪貂间进行传播试验，以评估这些病毒株经由飞沫传播的可能性。结果显示，这些代表性的病毒中，唯有一种含欧亚型H1N1流感基质蛋白基因的北美型流感重组病毒株具有少许的飞沫传播能力。
研究人员利用流感病毒反向遗传学（一种基因工程方法，用于控制流感病毒基因的组合），将2009年流行的H1N1流感病毒的神经氨酸酶基因，加入这一株流感病毒，所得出的新病毒株，具有经由飞沫传播的能力。
研究人员最终得出结论，流感病毒要经由飞沫传播，病毒中的两个病毒表面蛋白，须达到活性的微妙平衡。
该研究报告已在美国国家科学院官方科学刊物《美国国家科学院院刊》中发表。
生物探索推荐英文摘要：
Hemagglutinin–neuraminidase balance confers respiratory-droplet transmissibility of the pandemic H1N1 influenza virus in ferrets
Abstract
A novel reassortant derived from North American triple-reassortant (TRsw) and Eurasian swine (EAsw) influenza viruses acquired sustained human-to-human transmissibility and caused the 2009 influenza pandemic. To identify molecular determinants that allowed efficient transmission of the pandemic H1N1 virus among humans, we evaluated the direct-contact and respiratory-droplet transmissibility in ferrets of representative swine influenza viruses of different lineages obtained through a 13-y surveillance program in southern China. Whereas all viruses studied were transmitted by direct contact with varying efficiency, respiratory-droplet transmissibility (albeit inefficient) was observed only in the TRsw-like A/swine/Hong Kong/915/04 (sw915) (H1N2) virus. The sw915 virus had acquired the M gene derived from EAsw and differed from the gene constellation of the pandemic H1N1 virus by the neuraminidase (NA) gene alone. Glycan array analysis showed that pandemic H1N1 virus A/HK/415742/09 (HK415742) and sw915 possess similar receptor-binding specificity and affinity for α2,6-linked sialosides. Sw915 titers in differentiated normal human bronchial epithelial cells and in ferret nasal washes were lower than those of HK415742. Introducing the NA from pandemic HK415742 into sw915 did not increase viral replication efficiency but increased respiratory-droplet transmissibility, despite a substantial amino acid difference between the two viruses. The NA of the pandemic HK415742 virus possessed significantly higher enzyme activity than that of sw915 or other swine influenza viruses. Our results suggest that a unique gene constellation and hemagglutinin–neuraminidase balance play a critical role in acquisition of efficient and sustained human-to-human transmissibility.
