Crittenden L B, Witter R L, Okazaki W, Neiman P E
J Natl Cancer Inst. 1979 Jul;63(1):191-200.
More than 4,500 breeding female chickens of nine inbred lines maintained under specific-pathogen-free conditions to approximately 500 days of age were studied. Routine monitoring and special assays indicated that they were free of infection by exogenous viruses of the leukosis-sarcoma and the reticuloendotheliosis groups. Some birds were maintained free of Marek's disease (MD) virus infection in plastic isolators, and others were maintained in conventional chicken houses and vaccinated with the herpesvirus of turkeys to prevent the lesions of MD. Ten birds bearing lymphoid tumors were observed in two sublines of one line of chickens known to produce embryos that spontaneously produce Rous-associated virus, type 0 (RAV-O), an endogenous virus of the chicken. Four tumors were found in chickens of one subline maintained free of MD virus infection in isolators. These tumors did not involve the bursa and had some histologic features different from those typical of lymphoid leukosis. Six tumors were found in chickens of the other subline that were vaccinated to prevent MD; these tumors involved the bursa and were typical of lymphoid leukosis but not MD. These results suggest that two types of tumors may have been observed. The fact that DNA extracted from both types of tumors did not contain exogenous lymphoid leukosis virus sequences confirms the virologic evidence that exogenous viruses were not involved. The fact that endogenous viral sequences were not increased in copy number suggests that the endogenous virus RAV-O did not directly induce the tumors. Two birds with tumors not involving the bursa were found alive, and transplantable lymphoid tumors were developed. These tumors were of T-cell origin rather than of bursa cell origin as would be expected of lymphoid leukosis. These are the first reported lymphoid tumors that have been observed in the absence of known exogenous tumor virus infection in chickens. Our evidence suggests that the endogenous virus RAV-O did not play a primary role in the induction of these tumors.
对9个近交系的4500多只种母鸡进行了研究，这些母鸡在无特定病原体条件下饲养至约500日龄。常规监测和特殊检测表明，它们未感染白血病 - 肉瘤组和网状内皮增生症组的外源病毒。一些鸡在塑料隔离器中饲养，未感染马立克氏病（MD）病毒，另一些鸡饲养在传统鸡舍中，并用火鸡疱疹病毒疫苗接种以预防MD病变。在已知能产生自发产生罗氏相关病毒0型（RAV - O，一种鸡内源性病毒）胚胎的一个品系的两个亚系中，观察到10只患有淋巴肿瘤的鸡。在隔离器中饲养且未感染MD病毒的一个亚系的鸡中发现了4个肿瘤。这些肿瘤未累及法氏囊，并且具有一些与典型淋巴白血病不同的组织学特征。在接种疫苗以预防MD的另一个亚系的鸡中发现了6个肿瘤；这些肿瘤累及法氏囊，是典型的淋巴白血病而非MD。这些结果表明可能观察到了两种类型的肿瘤。从两种类型的肿瘤中提取的DNA均不包含外源淋巴白血病病毒序列，这一事实证实了病毒学证据，即外源病毒未参与其中。内源性病毒序列拷贝数未增加这一事实表明内源性病毒RAV - O未直接诱导肿瘤。发现两只肿瘤未累及法氏囊的鸡存活，并形成了可移植的淋巴肿瘤。这些肿瘤起源于T细胞，而不是如淋巴白血病所预期的起源于法氏囊细胞。这些是首次报道的在鸡中未发现已知外源肿瘤病毒感染的情况下观察到的淋巴肿瘤。我们的证据表明内源性病毒RAV - O在这些肿瘤的诱导中未起主要作用。
