Carr J K, Traina-Dorge V L, Cohen J C
Virology. 1985 Nov;147(1):210-3. doi: 10.1016/0042-6822(85)90241-7.
Expression of mouse mammary tumor virus (MMTV) in the lactating mammary glands of uninfected mice varies between strains of mice in a manner largely independent of the proviral content. Previous linkage analysis in the mouse suggested that the Lps locus was associated with steady-state levels of MMTV RNA. The Lps locus mediates the mouse's response to the injection of lipopolysaccharide (LPS) in the responder mouse while mice with the deficient allele are incapable of responding. Injecting LPS-responder mice, C3HfB/HeN, and nonresponder mice, C3Hf/HeJ, with LPS resulted in a threefold increase in the level of MMTV RNA in responder mice but had no effect on nonresponders. The increased level was due to only one of the possible MMTV transcripts: the 1.7-kb transcript containing the open reading frame (orf) of the long terminal repeat (LTR). The level of MMTV-specific transcripts, then, is regulated by the Lps locus, a cellular gene which is not linked to any viral coding sequences and therefore must act in trans.
未感染小鼠的泌乳乳腺中，小鼠乳腺肿瘤病毒（MMTV）的表达在不同品系小鼠之间存在差异，这种差异在很大程度上与前病毒含量无关。此前在小鼠中的连锁分析表明，Lps基因座与MMTV RNA的稳态水平相关。Lps基因座介导了应答型小鼠对注射脂多糖（LPS）的反应，而具有缺陷等位基因的小鼠则无反应能力。给LPS应答型小鼠C3HfB/HeN和无反应能力小鼠C3Hf/HeJ注射LPS后，应答型小鼠体内MMTV RNA水平增加了三倍，但对无反应能力小鼠没有影响。增加的水平仅归因于MMTV可能的转录本之一：包含长末端重复序列（LTR）开放阅读框（orf）的1.7kb转录本。因此，MMTV特异性转录本的水平受Lps基因座调控，Lps是一个细胞基因，与任何病毒编码序列均无关联，因此必定以反式作用发挥作用。
