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

高致病性禽流感（HPAI）H5 N1病毒具有对禽类和哺乳动物的高致病性和独特的器官嗜性。 在这里，我们显示了一个新的内化途径的高致病性禽流感H5 N1病毒没有2-3连接的唾液酸的细胞表面。结果表明，经神经氨酸酶去除细胞表面唾液酸后，高致病性禽流感病毒H5 N1能感染细胞，而低致病性禽流感病毒H5 N1不能感染细胞，感染细胞产生的病毒颗粒具有完整的感染性。然后，我们确定了HPAI H5 N1的多碱基序列（MBS）是一种细胞穿透肽（CPP），已知其具有穿透细胞膜的能力。GFP与MBS融合蛋白可被多种细胞内化，MBS特异性抗体可阻止融合蛋白的内化。

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.