Submitted to: Avian Diseases
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/27/2012
Publication Date: 9/30/2012
Citation: Pandiri, A.R., Gimeno, I.M., Mays, J.K., Reed, W.M., Fadly, A.M. 2012. Reversion to subgroup J avian leukosis virus viremia in seroconverted adult meat-type chickens exposed to chronic stress by adrenocorticotrophin treatment. Avian Diseases. 56:578-582. Interpretive Summary: Avian leukosis virus (ALV) can cause cancer-like disease and other production problems in affected chicken flocks. Most if not all of primary chicken breeders have adopted programs for reduction or eradication of ALV infection in their breeding stocks. Such programs are primarily based on testing breeders and the elimination of those that are positive. Occasionally, chickens that clear ALV from their blood (viremia-free) by developing an efficient antibody response revert to ALV viremia; factors responsible for such reversion are not clear. In this study, we found that artificially induced stress may result in reversion to ALV viremia in chickens originally exposed to virus at hatch, but not in those that were contact-exposed at 32 weeks of age. The information suggests that stress can lead to reversion to ALV viremia in chickens that already cleared the virus from their blood; this information should be important to chicken breeders and growers who are interested in elimination of ALV infection from their flocks.
Technical Abstract: Chickens infected with Subgroup J avian leukosis virus (ALV J) early in post-hatch life develop viremia followed by a neutralizing antibody (NAb) response that may or may not be able to clear 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 have since cleared viremia and remained viremia-free for up to 40 weeks, 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 weeks 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 weeks of age. The results warrant further studies with greater sample size to examine the role of stress in ALV J epidemiology.