Powell R M, Ward T, Evans D J, Almond J W
School of Animal and Microbial Sciences, University of Reading, Whiteknights, United Kingdom.
J Virol. 1997 Dec;71(12):9306-12. doi: 10.1128/JVI.71.12.9306-9312.1997.
Soluble forms of decay-accelerating factor (DAF) (CD55), the receptor for echovirus 7, were synthesized in the yeast Pichia pastoris. Purified recombinant protein containing SCR domains 2, 3, and 4, but lacking the serine/threonine rich region, was shown to block infection of susceptible cells by echovirus 7. In contrast to the situation with poliovirus and its receptor, the neutralization of echovirus 7 by soluble DAF was completely reversible and did not lead to the formation of 135S A-particles. Binding of virus to susceptible cells, by contrast, did lead to the formation of A particles, mainly from virus that had been internalized. The data suggest that a secondary factor(s) may contribute to A-particle formation and uncoating of echovirus 7.
衰变加速因子(DAF,即CD55)的可溶性形式,作为埃可病毒7的受体,在毕赤酵母中合成。纯化后的重组蛋白包含第2、3和4个短共识重复序列(SCR)结构域,但缺少富含丝氨酸/苏氨酸的区域,该蛋白可阻断埃可病毒7对易感细胞的感染。与脊髓灰质炎病毒及其受体的情况不同,可溶性DAF对埃可病毒7的中和作用是完全可逆的,且不会导致135S A颗粒的形成。相比之下,病毒与易感细胞的结合确实会导致A颗粒的形成,主要来自内化的病毒。数据表明,可能有第二个因素促成了埃可病毒7的A颗粒形成和解衣壳过程。