Smith Jason G, Mothes Walther, Blacklow Stephen C, Cunningham James M
Department of Medicine. Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.
J Virol. 2004 Feb;78(3):1403-10. doi: 10.1128/jvi.78.3.1403-1410.2004.
The spring-loaded model stipulates that influenza virus infection is coupled to the transition of the virus hemagglutinin (HA) from a metastable conformation to a highly stable conformation at low pH. The properties of retrovirus envelope glycoproteins indicate that infection is coupled to an analogous conformational change. As a test of this hypothesis, the requirements for avian leukosis virus A (ALV-A) infection were examined. These studies indicate that, like HA, the conformation of the mature ALV-A envelope glycoprotein is metastable and that infection is linked to refolding at low pH. However, unlike HA, low-pH activation is only observed after priming by receptor. Therefore, ALV-A infection is dependent on the synergistic effects of receptor binding and low pH, suggesting that receptor binding superimposes an additional constraint on activation of ALV-A fusion that proceeds by a mechanism comparable to that of influenza virus.
弹簧加载模型规定，流感病毒感染与病毒血凝素（HA）在低pH值下从亚稳态构象转变为高度稳定构象相关联。逆转录病毒包膜糖蛋白的特性表明，感染与类似的构象变化相关联。作为对这一假设的检验，研究了禽白血病病毒A（ALV-A）感染的条件。这些研究表明，与HA一样，成熟的ALV-A包膜糖蛋白的构象是亚稳态的，并且感染与低pH值下的重折叠有关。然而，与HA不同的是，低pH激活仅在受体引发后才观察到。因此，ALV-A感染依赖于受体结合和低pH的协同作用，这表明受体结合对ALV-A融合激活施加了额外的限制，其激活机制与流感病毒的机制类似。
