Lowy D R, Rands E, Scolnick E M
J Virol. 1978 May;26(2):291-8. doi: 10.1128/JVI.26.2.291-298.1978.
We have studied the unintegrated infectious DNA of Harvey sarcoma virus (Ha-SV) and Moloney leukemia virus (Mo-MuLV). The source of infectious viral DNA was the Hirt supernatant fraction from cells acutely infected with Ha-SV and Mo-MuLV. To obtain a direct quantitative assay for infectious viral DNA, recipient mouse cells were first exposed to calcium phosphate-precipitated viral DNA and then treated with dimethyl sulfoxide. Infectivity was monitored by focus formation for Ha-SV and XC plaque formation for Mo-MuLV. The viral DNA titration pattern followed single-hit kinetics for both foci and plaques, indicating that a single molecule carried information for each function. Focus-forming and plaque-forming activity were present in different molecules, since these two biological activities could be separated from each other by agarose gel electrophoresis. The focus-forming molecule was linear DNA with a molecular weight of about 4 x 10(6) daltons. The focus-forming activity of the viral DNA was sensitive to EcoRI and resistant to XhoI restriction endonucleases, whereas the plaque-forming activity was resistant to EcoRI and sensitive to XhoI. The generation of helper-independent foci indicates that Ha-SV DNA can transform mouse cells in the absence of helper virus or its proteins.
我们研究了哈维肉瘤病毒（Ha-SV）和莫洛尼白血病病毒（Mo-MuLV）的未整合感染性DNA。感染性病毒DNA的来源是急性感染Ha-SV和Mo-MuLV的细胞的赫特上清液部分。为了获得感染性病毒DNA的直接定量测定方法，首先将受体小鼠细胞暴露于磷酸钙沉淀的病毒DNA，然后用二甲基亚砜处理。通过Ha-SV的灶形成和Mo-MuLV的XC噬斑形成来监测感染性。病毒DNA滴定模式对灶和噬斑均遵循单 hit 动力学，表明单个分子携带每种功能的信息。灶形成活性和噬斑形成活性存在于不同分子中，因为这两种生物学活性可以通过琼脂糖凝胶电泳彼此分离。灶形成分子是分子量约为4×10⁶道尔顿的线性DNA。病毒DNA的灶形成活性对EcoRI敏感，对XhoI限制性内切酶有抗性，而噬斑形成活性对EcoRI有抗性，对XhoI敏感。非依赖辅助病毒的灶的产生表明，Ha-SV DNA可以在没有辅助病毒或其蛋白质的情况下转化小鼠细胞。
