Graham Kate L, Takada Yoshikazu, Coulson Barbara S
Department of Microbiology and Immunology, The University of Melbourne, Victoria 3010, Australia.
The University of California, Davis, UC Davis Medical Center, 4645 2nd Avenue, Sacramento, CA 95817, USA.
J Gen Virol. 2006 May;87(Pt 5):1275-1283. doi: 10.1099/vir.0.81580-0.
Rotaviruses recognize several cell-surface molecules, including the alpha2beta1 integrin, and the processes of rotavirus cell attachment and entry appear to be multifactorial. The VP5* subunit of the rotavirus spike protein VP4 contains the alpha2beta1 ligand sequence Asp-Gly-Glu at residues 308-310. Binding to alpha2beta1 and infectivity of monkey rotavirus strain RRV and human rotavirus strain Wa, but not porcine rotavirus strain CRW-8, are inhibited by peptides containing Asp-Gly-Glu. Asp308 and Gly309 are necessary for the binding of RRV VP5* (aa 248-474) to expressed I domain of the alpha2 integrin subunit. Here, the ability of RRV VP5* to bind cells and affect rotavirus-integrin interactions was determined. Interestingly, VP5* bound to cells at 4 and 37 degrees C, both via alpha2beta1 and independently of this integrin. Prior VP5* binding at 37 degrees C eliminated RRV binding to cellular alpha2beta1 and reduced RRV and Wa infectivity in MA104 cells by 38-46 %. VP5* binding did not affect the infectivity of CRW-8. VP5* binding at 4 degrees C did not affect permissive-cell infection by RRV, indicating an energy requirement for VP5* competition with virus for infectivity. Mutagenesis of VP5* Asp308 and Gly309 eliminated VP5* binding to alpha2beta1 and the VP5* inhibition of rotavirus cell binding and infection, but not alpha2beta1-independent cell binding by VP5*. These studies show for the first time that expressed VP5* binds cell-surface alpha2beta1 using Asp308 and Gly309 and inhibits the infection of homologous and heterologous rotaviruses that use alpha2beta1 as a receptor.
轮状病毒可识别多种细胞表面分子，包括α2β1整合素，并且轮状病毒的细胞附着和进入过程似乎是多因素的。轮状病毒刺突蛋白VP4的VP5亚基在308 - 310位残基处含有α2β1配体序列天冬氨酸-甘氨酸-谷氨酸。含有天冬氨酸-甘氨酸-谷氨酸的肽可抑制猴轮状病毒株RRV和人轮状病毒株Wa与α2β1的结合及感染性，但对猪轮状病毒株CRW - 8无此作用。天冬氨酸308和甘氨酸309是RRV VP5（氨基酸248 - 474）与α整合素亚基的表达I结构域结合所必需的。在此，测定了RRV VP5结合细胞以及影响轮状病毒 - 整合素相互作用的能力。有趣的是，VP5在4℃和37℃均可与细胞结合，既通过α2β1，也独立于该整合素。37℃下预先存在的VP5结合消除了RRV与细胞α2β1的结合，并使MA104细胞中RRV和Wa的感染性降低38 - 46%。VP5结合不影响CRW - 8的感染性。4℃下VP5结合不影响RRV对允许性细胞的感染，这表明VP5与病毒竞争感染性存在能量需求。VP5天冬氨酸308和甘氨酸309的诱变消除了VP5与α2β1的结合以及VP5对轮状病毒细胞结合和感染的抑制作用，但未消除VP5独立于α2β1的细胞结合。这些研究首次表明，表达的VP5*利用天冬氨酸308和甘氨酸309结合细胞表面的α2β1，并抑制以α2β1作为受体的同源和异源轮状病毒的感染。
