Astrin S M, Buss E G, Haywards W S
Nature. 1979 Nov 15;282(5736):339-41. doi: 10.1038/282339a0.
DNA sequences homologous to the genomes of type C retroviruses are widespread among vertebrates. Ten genetic loci containing endogenous viral DNA sequences have been documented in the white Leghorn chicken alone. Six of these genetic loci are associated with the production of virus or of viral proteins in embryonic fibroblasts (refs 2--4, and S.M.A., L, B. Crittenden and E.G.B., in preparation) and one of the loci may be expressed in the erythroblasts of 5-day-old embryos. The abiquitous presence of endogenous viral genes among vertebrate species and the association of their expression with development of the haematopoietic system in the mouse have led to the proposal that these genes are involved in ontogeny. In addition, the genes may be implicated in oncogenesis as in the case of the AKR mouse in which a high incidence of spontaneous leukaemia is associated with the expression of endogenous murine laukaemia virus genomes. We report here the production of a fertile rooster which lacks avian leukosis virus-related endogenous viral genes and which seems to be completely normal and healthy. Thus, endogenous viral genes are apparently not essential for the normal development of the chicken. An endogenous virus-free state has also been reported for three species of jungle fowl and for the B-type viral genes of the mouse.
与C型逆转录病毒基因组同源的DNA序列在脊椎动物中广泛存在。仅在白来航鸡中就已记录到10个含有内源性病毒DNA序列的基因位点。其中6个基因位点与胚胎成纤维细胞中病毒或病毒蛋白的产生有关（参考文献2 - 4，以及S.M.A.、L、B.克里滕登和E.G.B.正在准备的研究），并且其中一个位点可能在5日龄胚胎的成红细胞中表达。脊椎动物物种中内源性病毒基因的普遍存在以及它们的表达与小鼠造血系统发育的关联，引发了这些基因参与个体发育的提议。此外，这些基因可能与肿瘤发生有关，就像AKR小鼠的情况一样，其自发白血病的高发病率与内源性鼠白血病病毒基因组的表达相关。我们在此报告了一只可育公鸡的产生，它缺乏与禽白血病病毒相关的内源性病毒基因，并且看起来完全正常健康。因此，内源性病毒基因显然对于鸡的正常发育并非必不可少。对于三种原鸡以及小鼠的B型病毒基因，也报道了无内源性病毒的状态。
