Reversion to subgroup J avian leukosis virus viremia in seroconverted adult meat-type chickens exposed to chronic stress by adrenocorticotrophin treatment.

Chickens infected with subgroup J avian leukosis virus (ALV J) early in posthatch life develop viremia followed by a neutralizing antibody (Nab) response that may or may not be able to clear the viremia. Occasionally, chickens that do clear viremia by developing an efficient Nab response revert to viremia, and the factors responsible for this reversion are not clear. In this study, it was hypothesized that stress can cause seroconverted viremia-free chickens to revert to viremia. Adult (52-wk-old) male commercial meat-type chickens that were exposed to ALV J at hatch and had since cleared viremia and remained viremia-free for up to 40 wk, when subjected to chronic stress (for 14 days) induced by porcine adrenocorticotrophin (ACTH), reverted to viremia and cloacal shedding (2/6 [33%]). However, chickens that were contact-exposed to ALV J at 32 wk of age and had seroconverted failed to revert to viremia when subjected to similar chronic stress. Stress did not increase the susceptibility of adult meat-type chickens to ALV J infection by contact exposure. The lack of statistical significance due to the small sample size is a limitation of this study. However, in general, the results suggest that treatment of chickens with ACTH can cause reversion of viremia and cloacal shedding in ALV J-seroconverted adult male chickens that had been exposed to the virus at hatch, but not in chickens that were contact-exposed at 32 wk of age. The results warrant further studies with greater sample size to examine the role of stress in ALV J epidemiology.