Fadly A M, Okazaki W, Crittenden L B
Avian Dis. 1983 Jul-Sep;27(3):584-93.
Two lines (D and E) of three breeder lines of chickens that had resisted selection for reduced avian leukosis virus (ALV) congenital transmission on the breeder's premises did not resist the same selection procedures (tests for gs-antigen in albumen) under laboratory conditions. The incidence of ALV congenital transmission in the remaining third line (F) was spontaneously reduced from 13% to 0.9%. Environmental ALV exposure of uninfected chicks after hatching induced 7-10% of the progeny from lines E and F to become congenital transmitters but had negligible effects on line D. Neither errors in identifying dams nor horizontal transmission leading to congenital transmission were great enough to explain the lack of improvements in the three lines on the breeder's premises. Conditions of environmental exposure on the breeder's farm seem most likely to account for the resistance to reduced shedding. These findings suggest that the effectiveness of testing and selection procedures used to reduce ALV may be greatly influenced by the environment.
在种鸡场对三个种鸡品系进行选育以降低禽白血病病毒（ALV）先天性传播时，其中两个品系（D和E）未在种鸡场成功，但在实验室条件下对相同的选育程序（检测蛋清中的gs抗原）却没有抗性。第三个品系（F）中，ALV先天性传播的发生率从13%自发降至0.9%。未感染的雏鸡在孵化后暴露于环境中的ALV，导致E和F品系7%-10%的后代成为先天性传播者，但对D品系影响可忽略不计。无论是确定母鸡时的误差，还是导致先天性传播的水平传播，都不足以解释种鸡场这三个品系选育未取得进展的原因。种鸡场的环境暴露条件似乎最有可能是导致对降低排毒有抗性的原因。这些发现表明，用于降低ALV的检测和选育程序的有效性可能会受到环境的极大影响。
