Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/26/2008
Publication Date: 12/15/2008
Citation: Abdul-Careem, M.F., Hunter, D.B., Shanmuganathan, S., Haghighi, H.R., Read, L., Heidari, M., Sharif, S. 2008. Cellular and Cytokine Responses in Feathers of Chickens Vaccinated Against Marek's Disease. Veterinary Immunology and Immunopathology. 126(3-4):362-366. Available: http://www.sciencedirect.com/science/journal/01652427. Interpretive Summary: Marek’s disease (MD) causes enormous economical losses to the poultry industry. Marek’s disease virus (MDV), the etiological agent of MD, is a herpesvirus that causes the suppression of immune system and evasion of immune responses in infected chickens. Cytokines are secreted proteins, which are important mediators and regulators of both innate and adaptive type of host responses. The main function of cytokines is orchestrating the functional activities of the cells of the immune system. The objective of this study was to investigate the cellular and cytokine responses in the feathers of chickens vaccinated against MDV, as feathers are the only anatomical site for replication and dissemination of virus particles. Evaluation of feather samples collected at various time post-vaccination revealed that both of MDV vaccines used termed, CVI988 and HVT replicated beginning from 7 dpi and peaked by 21 dpi and, subsequently, showed a declining trend. This pattern of viral replication leading to viral genome accumulation in feathers was associated with infiltration of immune cells known as T cell subsets into the feather pulp area and the expression of cytokine genes such as interferon-gamma. This study sheds light on the mechanism of immune responses induced by vaccination in the feather pulp and provides groundwork for future studies in immunomodulatory efforts for prevention and control of this important viral infection of chickens.
Technical Abstract: The objective of the study was to characterize cellular and cytokine responses as indicators of cell-mediated immune response in feathers of chickens vaccinated against Marek’s disease (MD). Feathers constitute the site of virus shedding in the case of Marek’s disease virus (MDV). The feather samples collected on 4, 7, 10, 14, 21 and 28 days post immunization (d.p.i.) in chicken vaccinated with CVI988/Rispens or with herpesvirus of turkeys (HVT) on day 1 post-hatch revealed that CVI988 and HVT vaccine viruses replicated beginning from 7 d.p.i. and peaked by 21 dp.i. and, subsequently, showed a declining trend. This pattern of viral replication leading to viral genome accumulation in feathers was associated with infiltration of T cell subsets particularly CD8+ T cells into the feather pulp area and the expression of cytokine genes such as interferon (IFN)-gamma. In conclusion, both CVI988 and HVT vaccine viruses replicated in feathers and stimulated local cell-mediated immune responses.