New entry pathway of highly pathogenic avian influenza virus without sialic acid .

高致病性禽流感(HPAI)H5N1病毒对感染的禽类和哺乳动物具有高致病性和独特的器官嗜性。在这里，我们展示了HPAI H5N1病毒的一种新的内化途径，细胞表面没有2-3个连接的唾液酸。我们发现HPAI H5N1病毒不能感染低致病性禽流感(LPAI)H5N1病毒在神经氨酸酶去除细胞表面唾液酸的细胞中感染，感染的细胞产生具有完整感染力的病毒颗粒。HPAI H5N1的多碱基序列(MBS)是一种细胞穿透肽(CPPs)，具有穿透细胞膜的能力。GFP与MBS融合后可内化到多种细胞中，而针对MBS的特异性抗体可阻止融合蛋白内化。

Highly pathogenic avian influenza (HPAI) H5N1 virus was characterized by the high pathogenicity and unique organ tropism for infected avian and mammalian. Here we show a new internalized pathway of HPAI H5N1 virus without 2-3 linked sialic acids on the cell surface. We revealed that HPAI H5N1 virus but not low pathogenic avian influenza (LPAI) H5N1 virus could infect in cells treated with neuraminidase for removing sialic acid on the cell surface, and the infected cells generated viral particles with intact infectivity. We then identified the multi-basic sequence (MBS) of HPAI H5N1 as a kind of cell penetrating peptides (CPPs) which is known to have an ability of penetrating cellular membrane. GFP fused with MBS could internalize into several kinds of cells, and specific antibody against MBS prevented the fusion protein from internalizing.