Evans L H, Malik F G
J Virol. 1987 Jun;61(6):1882-92. doi: 10.1128/JVI.61.6.1882-1892.1987.
We examined the frequency of occurrence of polytropic murine leukemia viruses (MuLVs) in the spleens and thymuses of preleukemic AKR/J mice from 1 week to 6 months of age and analyzed the genomic RNAs of several polytropic isolates by RNase T1 oligonucleotide fingerprinting. Polytropic MuLVs were first detected in the spleens of 3-week-old mice and preceded the appearance of polytropic MuLVs in the thymus by over 1 month. At 4 months of age and older, nearly all mice expressed polytropic MuLVs in both organs. In contrast to previous studies which have identified class I polytropic MuLVs in AKR/J mice, fingerprint analysis of polytropic MuLVs from both young (3- to 4-week-old) and older (5- to 6-month-old) preleukemic mice indicated that a large proportion of viruses at both ages were class II polytropic MuLVs. All polytropic viruses (five isolates) analyzed from 3- to 4-week-old mice were recovered from spleen cells and were class II polytropic MuLVs. In older preleukemic mice, five of seven isolates were class II polytropic MuLVs and two were class I polytropic viruses. Class I and class II polytropic MuLVs were recovered from both the spleens and thymuses of older preleukemic mice. A detailed comparison of the class I and class II polytropic MuLVs from 5- to 6-month-old mice revealed that the nonecotropic gp70 sequences of most of the class I and class II MuLVs were identical, consistent with a common origin for these sequences. In contrast, the nonecotropic p15E sequences of class I MuLVs were clearly derived from different endogenous sequences than the nonecotropic p15E sequences of the class II MuLVs. The in vitro host ranges of class I and class II polytropic viruses were clearly distinguishable. Examination of the in vitro host range of several isolates suggested that the predominant polytropic viruses initially identified in the thymus (2 to 3 months of age) were class II polytropic viruses. The order of appearance of the class I and class II polytropic MuLVs and the identity of the gp70 oligonucleotides of these MuLVs suggested a model for the stepwise generation of class I polytropic MuLVs involving a class II polytropic MuLV intermediate.
我们检测了白血病前期AKR/J小鼠从1周龄到6月龄时脾脏和胸腺中多嗜性鼠白血病病毒（MuLVs）的出现频率，并通过核糖核酸酶T1寡核苷酸指纹图谱分析了几种多嗜性分离株的基因组RNA。多嗜性MuLVs首先在3周龄小鼠的脾脏中被检测到，比在胸腺中出现多嗜性MuLVs早1个多月。在4月龄及以上的小鼠中，几乎所有小鼠的两个器官中都表达了多嗜性MuLVs。与之前在AKR/J小鼠中鉴定出I类多嗜性MuLVs的研究不同，对幼年（3至4周龄）和老年（5至6月龄）白血病前期小鼠的多嗜性MuLVs进行指纹分析表明，两个年龄段的病毒中很大一部分是II类多嗜性MuLVs。从3至4周龄小鼠中分析的所有多嗜性病毒（五个分离株）均从脾细胞中分离得到，且为II类多嗜性MuLVs。在老年白血病前期小鼠中，七个分离株中有五个是II类多嗜性MuLVs，两个是I类多嗜性病毒。I类和II类多嗜性MuLVs均从老年白血病前期小鼠的脾脏和胸腺中分离得到。对5至6月龄小鼠的I类和II类多嗜性MuLVs进行详细比较发现，大多数I类和II类MuLVs的非嗜异性gp70序列相同，这与这些序列的共同起源一致。相比之下，I类MuLVs的非嗜异性p15E序列与II类MuLVs的非嗜异性p15E序列明显源自不同的内源性序列。I类和II类多嗜性病毒的体外宿主范围明显不同。对几种分离株的体外宿主范围进行检测表明，最初在胸腺（2至3月龄）中鉴定出的主要多嗜性病毒是II类多嗜性病毒。I类和II类多嗜性MuLVs的出现顺序以及这些MuLVs的gp70寡核苷酸的一致性提示了一个涉及II类多嗜性MuLV中间体的I类多嗜性MuLV逐步产生的模型。
