Mathews J H, Vorndam A V
J Gen Virol. 1982 Aug;61 (Pt 2):177-86. doi: 10.1099/0022-1317-61-2-177.
A persistent infection with Saint Louis encephalitis (SLE) virus in a poikilothermic cell line TH-1 (turtle heart cells) was studied. Infected TH-1 cells were subcultured weekly at 31 degrees C for 1 year and continued to produce low levels (10(2) to 10(3) p.f.u./ml) of virus without obvious cytopathic effects or marked cyclic events. Indirect fluorescent antibody and infectious centre assays indicated that less than 1% of the cells were producing detectable virus proteins or infectious virus. Defective-interfering particles, temperature-sensitive mutants and DNA provirus were not detected. Interferon (IFN) mediation of the persistent infection as considered since the persistently infected cells (PIC) and normal TH-1 cells were resistant to heterologous virus challenge after treatment with virus-free culture fluid from PIC. A direct relationship was found between the m.o.i. and the amount of IFN produced, plateauing at an m.o.i. of approx. 10. The reptilian IFN was physically and chemically similar to mammalian and avian IFN. Certain biological markers of the SLE virus changed during the persistent infection. It was less virulent for mice, showed distinct differences in cell culture host range and had increased thermal lability.
对圣路易斯脑炎（SLE）病毒在变温细胞系TH - 1（龟心脏细胞）中的持续性感染进行了研究。感染的TH - 1细胞每周在31摄氏度传代培养1年，持续产生低水平（10²至10³ 蚀斑形成单位/毫升）的病毒，无明显细胞病变效应或显著的周期性事件。间接荧光抗体和感染中心检测表明，不到1%的细胞产生可检测到的病毒蛋白或感染性病毒。未检测到缺陷干扰颗粒、温度敏感突变体和DNA前病毒。考虑到持续性感染细胞（PIC）和正常TH - 1细胞在用来自PIC的无病毒培养液处理后对异源病毒攻击具有抗性，因此探讨了干扰素（IFN）对持续性感染的介导作用。发现感染复数（m.o.i.）与产生的IFN量之间存在直接关系，在m.o.i.约为10时达到平稳。爬行动物IFN在物理和化学性质上与哺乳动物和鸟类IFN相似。SLE病毒的某些生物学特性在持续性感染期间发生了变化。它对小鼠的毒性降低，在细胞培养宿主范围上表现出明显差异，并且热稳定性增加。
