Foo Chwan Hong, Lou Huan, Whitbeck J Charles, Ponce-de-León Manuel, Atanasiu Doina, Eisenberg Roselyn J, Cohen Gary H
Department of Microbiology, School of Dental Medicine, University of Pennsylvania, 240 S. 40th St, Levy Rm 233, Philadelphia, PA 19104, USA.
Virology. 2009 Mar 15;385(2):368-82. doi: 10.1016/j.virol.2008.12.019. Epub 2009 Jan 21.
L1 and A28 are vaccinia virus (VACV) envelope proteins which are essential for cellular entry. However, their specific roles during entry are unknown. We tested whether one or both of these proteins might serve as receptor binding proteins (RBP). We found that a soluble, truncated form of L1, but not A28, bound to cell surfaces independently of glycosaminoglycans (GAGs). Hence, VACV A28 is not likely to be a RBP and functions after attachment during entry. Importantly, soluble L1 inhibited both binding and entry of VACV in GAG-deficient cells, suggesting that soluble L1 blocks entry at the binding step by competing with the virions for non-GAG receptors on cells. In contrast, soluble A27, a VACV protein which attaches to GAGs but is non-essential for virus entry, inhibited binding and entry of VACV in a GAG-dependent manner. To our knowledge, this is the first report of a VACV envelope protein that blocks virus binding and entry independently of GAGs.
L1和A28是痘苗病毒（VACV）包膜蛋白，对病毒进入细胞至关重要。然而，它们在病毒进入过程中的具体作用尚不清楚。我们测试了这两种蛋白中的一种或两种是否可能作为受体结合蛋白（RBP）。我们发现，一种可溶性的、截短形式的L1能独立于糖胺聚糖（GAGs）与细胞表面结合，而A28则不能。因此，VACV A28不太可能是一种RBP，其在病毒附着后发挥作用。重要的是，可溶性L1抑制了VACV在缺乏GAG的细胞中的结合和进入，这表明可溶性L1通过与病毒粒子竞争细胞上的非GAG受体，在结合步骤阻断了病毒进入。相比之下，可溶性A27是一种与GAGs结合但对病毒进入非必需的VACV蛋白，它以依赖GAG的方式抑制VACV的结合和进入。据我们所知，这是关于一种VACV包膜蛋白独立于GAGs阻断病毒结合和进入的首次报道。
