Becker D, Kurth R, Critchley D, Friis R, Bauer H
J Virol. 1977 Mar;21(3):1042-55. doi: 10.1128/JVI.21.3.1042-1055.1977.
Eight transformation-defective, temperature-sensitive (ts) mutants of the Prague strain of Rous sarcoma virus, subgroup A, have been isolated after mutagenesis with 5-bromodeoxyuridine followed by selection on the basis of focus tests. Five of these mutants, ts GI201, GI202, GI203, GI204, and GI205, exhibit properties like most previously reported isolates in that they show a temperature-sensitive response to each of a variety of transformation-specific parameters tested. Interestingly, GI201, in addition to the temperature-sensitive defect, carries a lesion that was observed as a nonconditional loss of expression of plasminogen activator protease. Three mutants, ts GI251, GI252, and GI253 have been disignated partial transformation-defective (PTD) mutants since they behave as ts mutants according to some tests for transformation and as wild type according to others. These three mutants fail to form foci at the nonpermissive temperature (41 degrees C) and art nontumorigenic in 3-week-old chickens (body temperature, 42 degrees C). The agglutinability by concanavalin A of cells infected with these mutants shows a definite temperature sensitivity, as do the rate of 2-deoxyglucose uptake and the disappearance of the 250, 000-dalton normal cell glycoprotein (large, external, transformation sensitive [LETS]). Although the PTD mutant-infected cells, unlike cells infected with other transformation mutants, exhibit a cell-bound plasminogen activator protease at the nonpermissive temperature, this activator is not detectable as a free protease in the medium, as it is with wild-type, virus-infected cells. The PTD mutants behave like the wild-type parent in their ability to induce transformed growth properties in the infected cells, i.e., growth beyond normal cell saturation density with or without serum-supplemented medium and growth leading to colony formation in soft-agar- or methyl cellulose-containing suspension media.
用5-溴脱氧尿苷诱变后，通过病灶试验进行筛选，已分离出罗氏肉瘤病毒布拉格株A亚群的8个转化缺陷型温度敏感（ts）突变体。其中5个突变体，ts GI201、GI202、GI203、GI204和GI205，表现出与大多数先前报道的分离株相似的特性，即它们对所测试的各种转化特异性参数均呈现温度敏感反应。有趣的是，GI201除了存在温度敏感缺陷外，还带有一个损伤，表现为纤溶酶原激活物蛋白酶表达的非条件性缺失。三个突变体，ts GI251、GI252和GI253，被指定为部分转化缺陷（PTD）突变体，因为根据某些转化试验它们表现为ts突变体，而根据其他试验则表现为野生型。这三个突变体在非允许温度（41℃）下不能形成病灶，并且在3周龄鸡（体温42℃）中不具有致瘤性。用这些突变体感染的细胞对刀豆球蛋白A的凝集性表现出明确的温度敏感性，2-脱氧葡萄糖摄取速率以及250,000道尔顿正常细胞糖蛋白（大的、外部的、转化敏感[LETS]）的消失也表现出温度敏感性。尽管与感染其他转化突变体的细胞不同，感染PTD突变体的细胞在非允许温度下表现出细胞结合的纤溶酶原激活物蛋白酶，但与野生型病毒感染的细胞不同，这种激活物在培养基中不能作为游离蛋白酶被检测到。PTD突变体在诱导感染细胞的转化生长特性方面表现得与野生型亲本相似，即在有或无血清补充培养基的情况下，生长超过正常细胞饱和密度，并在含软琼脂或甲基纤维素的悬浮培养基中生长导致集落形成。
