McCombs R M, Rawls W E
J Virol. 1968 May;2(5):409-14. doi: 10.1128/JVI.2.5.409-414.1968.
Rubella virus was centrifuged in sucrose density gradients. One of two densities could be ascribed to the virus, depending upon the suspending medium used. The virus was found at a density of 1.16 g/cm(3) after centrifugation for 18 hr in sucrose gradients prepared in distilled water. By contrast, when the sucrose gradients were prepared in tris(hydroxymethyl)aminomethane (Tris)buffer containing ethylenediaminetetraacetic acid (EDTA), the virus was found at a density of 1.18 g/cm(3) after 18 hr of centrifugation. The virus banded at this higher density after only 2 hr of centrifugation when pretreated by overnight incubation in the Tris-EDTA buffer. A kinetic study showed that, in sucrose gradients containing this buffer, the virus gradually migrated as a single peak of infectivity from a density of 1.16 g/cm(3) after 2 hr of centrifugation to the higher 1.18 g/cm(3) density after 18 hr. The density change was shown to be reversible; after the removal of the Tris-EDTA buffer, rebanding of virus harvested at the heavy density resulted in its banding at the lower 1.16 g/cm(3) density. The data indicate that density change could not be explained on the basis of the loss of some component from the virus or on the basis of the failure of the virus to reach equilibrium. However, it is possible that the two densities observed were a reflection of the existence of rubella virus in different hydration states in the presence and absence of Tris buffer containing EDTA.
风疹病毒在蔗糖密度梯度中进行离心。根据所使用的悬浮介质，病毒可呈现两种密度中的一种。在蒸馏水中制备的蔗糖梯度中离心18小时后，发现病毒的密度为1.16 g/cm³。相比之下，当在含有乙二胺四乙酸（EDTA）的三（羟甲基）氨基甲烷（Tris）缓冲液中制备蔗糖梯度时，离心18小时后发现病毒的密度为1.18 g/cm³。当在Tris-EDTA缓冲液中过夜孵育预处理后，病毒仅离心2小时就会在这个较高密度处形成条带。动力学研究表明，在含有这种缓冲液的蔗糖梯度中，病毒作为单一感染性峰逐渐迁移，离心2小时后密度为1.16 g/cm³，18小时后密度升至较高的1.18 g/cm³。密度变化被证明是可逆的；去除Tris-EDTA缓冲液后，在高密度处收获的病毒重新条带化，结果其条带位于较低的1.16 g/cm³密度处。数据表明，密度变化不能基于病毒某些成分的丢失或病毒未能达到平衡来解释。然而，有可能观察到的两种密度反映了在存在和不存在含EDTA的Tris缓冲液时风疹病毒处于不同水合状态的情况。
