Heinz F X, Stiasny K, Püschner-Auer G, Holzmann H, Allison S L, Mandl C W, Kunz C
Institute of Virology, University of Vienna, Austria.
Virology. 1994 Jan;198(1):109-17. doi: 10.1006/viro.1994.1013.
We have used tick-borne encephalitis virus to study the involvement of acidic compartments during the entry and release phases of flavivirus infection and to elucidate the role of protein prM in immature virions. Elevation of the pH in acidic intracellular compartments by either bafilyomycin A1, a specific inhibitor of the vacuolar type H(+)-ATPase or by NH4Cl had a strong inhibitory effect during virus penetration and also prevented the cleavage of prM when added in the late phase of the viral life cycle. In the latter case the release of virus particles was not impaired. These immature (prM-containing) virions exhibited a 20- to 50-fold lower specific infectivity and HA activity than mature virions and in contrast to these did not undergo low pH-triggered aggregation. The presence of prM also affected the binding of monoclonal antibodies to protein E, especially at sites which have been shown to undergo acid pH-induced conformational changes in mature virions. Crosslinking, solubilization, and sedimentation analyses revealed the existence of prM-E heterooligomeric complexes, suggesting that the function of prM is to protect protein E from undergoing the irreversible conformational changes in acidic compartments of the secretory pathway that are necessary for triggering fusion activity in the endosome during virus entry.
我们利用蜱传脑炎病毒来研究黄病毒感染的进入和释放阶段酸性区室的参与情况，并阐明蛋白prM在未成熟病毒粒子中的作用。通过液泡型H(+)-ATP酶的特异性抑制剂巴弗洛霉素A1或氯化铵提高酸性细胞内区室的pH值，在病毒穿透过程中具有很强的抑制作用，并且在病毒生命周期后期添加时也能阻止prM的切割。在后一种情况下，病毒粒子的释放不受影响。这些未成熟（含prM）病毒粒子的比感染性和血凝素（HA）活性比成熟病毒粒子低20至50倍，并且与成熟病毒粒子不同，它们不会发生低pH值触发的聚集。prM的存在还影响单克隆抗体与蛋白E的结合，特别是在已显示在成熟病毒粒子中会发生酸pH诱导的构象变化的位点。交联、溶解和沉降分析揭示了prM-E异源寡聚复合物的存在，这表明prM的功能是保护蛋白E在分泌途径的酸性区室中不发生不可逆的构象变化，而这种构象变化是病毒进入期间触发内体融合活性所必需的。
