Isolation of highly fusogenic variants of simian virus 5 from persistently infected cells that produce and respond to interferon
Isolation of highly fusogenic variants of simian virus 5 from persistently infected cells that produce and respond to interferon
复制标题
从产生干扰素并对其作出反应的持续感染细胞中分离出猿猴病毒 5 号的高度融合变种
作者：
D. Young;L. Didcock;R. Randall
进行了一系列实验来研究干扰素和中和抗体如何影响猿病毒 5 (SV5)（W3 株）在小鼠细胞中建立和维持持续感染的能力。与在产生干扰素并对其作出反应的小鼠 BALB/c 成纤维细胞（BF 细胞）中观察到的 SV5 蛋白合成迅速下降相反，在感染后 24 至 48 小时之间，MSFI-细胞（源自 α/β-干扰素受体敲除 BALB/c 小鼠的皮肤成纤维细胞）中的病毒蛋白合成没有受到抑制。此外，在受感染的 BF 细胞的培养基中添加抗干扰素抗体可显着减少观察到的病毒蛋白合成下降。感染未经处理的 BF 细胞后，大多数病毒会复制，但在感染后存活下来，并最终在 8 至 15 天后清除病毒。然而，并非所有细胞都被治愈，培养物持续受到感染。在持续感染的培养物传代后，由于干扰素的产生，病毒在活跃状态和抑制状态之间流动。这导致达到一种平衡，即任何时候只有 5% 到 20% 的细胞被感染。持续感染的细胞传代 30 代后，出现了高度融合的病毒变体（其中一种被分离出来，称为 W3-f）。 W3-f 仍然与亲本 W3 分离株一样对干扰素敏感，但在没有干扰素的情况下，通过 BF 细胞单层传播的速度比亲本 W3 菌株快得多。序列分析显示W3和W3-f的F蛋白之间没有推断出的氨基酸差异。通过向培养基中添加病毒中和抗体，可快速清除持续感染 W3-f 的 BF 细胞培养物中的病毒。相比之下，中和抗体对在数代中持续感染W3的细胞数量几乎没有影响。这些结果表明，副粘病毒引起细胞-细胞融合的能力可能是在体内被选择的，因为它们适应了干扰素反应，而不是它们需要逃避中和抗体。进一步讨论了这些观察结果对于体内持续性副流感病毒感染的意义。
A series of experiments were undertaken to examine how interferon and neutralizing antibodies influence the ability of simian virus 5 (SV5) (strain W3) to establish and maintain persistent infections in murine cells. In contrast to the rapid decline in SV5 protein synthesis observed in murine BALB/c fibroblasts (BF cells), which produce and respond to interferon, between 24 and 48 h postinfection there was no inhibition of virus protein synthesis in MSFI- cells, skin fibroblasts derived from alpha/beta-interferon receptor knockout BALB/c mice. Furthermore, the addition of anti-interferon antibodies to the culture medium of infected BF cells significantly reduced the observed decline in virus protein synthesis. Following infection of untreated BF cells, the majority replicated virus but survived the infection and eventually cleared the virus after 8 to 15 days. However, not all the cells were cured, and the cultures became persistently infected. Upon passage of persistently infected cultures, the virus fluxed between active and repressed states as a consequence of interferon production. This resulted in a balance being reached in which only 5 to 20% of the cells were infected at any one time. After 30 passages of the persistently infected cells, highly fusogenic virus variants arose (one of which was isolated and termed W3-f). W3-f remained as sensitive to interferon as the parental W3 isolate but, in the absence of interferon, spread much more rapidly than the parental W3 strain through BF cell monolayers. Sequence analysis revealed no deduced amino acid differences between the F proteins of W3 and W3-f. BF cell cultures persistently infected with W3-f were rapidly cleared of virus by the addition of virus-neutralizing antibodies to the culture medium. In contrast, neutralizing antibodies had little effect on the numbers of cells persistently infected with W3 over several passages. These results suggest that the ability of paramyxoviruses to cause cell-cell fusion may be selected for in vivo as a consequence of their adaptation to the interferon response rather than their need to escape from neutralizing antibodies. The significance of these observations with regard to persistent parainfluenza virus infections in vivo is further discussed.