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Title: Marek's disease virus induced transient paralysis--a closer look

Author
item Heidari, Mohammad
item XU, MING - Michigan State University

Submitted to: American Association of Avian Pathologists
Publication Type: Abstract Only
Publication Acceptance Date: 3/4/2011
Publication Date: 7/16/2011
Citation: Heidari, M., Xu, M. 2011. Marek's disease virus induced transient paralysis--a closer look [CD-ROM]. American Veterinary Medical Association (AVMA) Convention, July 16-19, 2011, St. Louis, Missouri. Paper No. 11068.

Interpretive Summary:

Technical Abstract: Marek’s Disease (MD) is a lymphoproliferative disease of domestic chickens caused by a highly cell-associated alpha herpesvirus, Marek’s disease virus (MDV). Clinical signs of MD include depression, crippling, weight loss, and transient paralysis (TP). TP is a disease of the central nervous system, which affects the MD-susceptible chickens 8-11 days post inoculation (dpi), normally resulting in death 1-3 days after the onset of clinical sign. Chickens from lines 7-2 (MD-susceptible) and 6-3 (MD-resistant) were inoculated with a highly pathogenic strain of MDV at one week of age and brain samples from birds with and without TP were collected at 5, 11, and 21 dpi for cytokine and other immune-related gene expression analysis and computation of viral genome copy number. Data revealed that chickens inoculated with MDV had higher levels of IL-6, IL-10, IL-18, IFN-alpha, IFN-beta, IFN-gamma, MHC I, and CD-18 in their brain tissues at 11 dpi compared to the uninfected control birds. In addition, the expression levels of IL-6, IL-10, IFN-alpha, IFN-beta, and IFN-gamma were significantly higher in the brain tissues of the birds showing clinical signs of TP in comparison to MDV-infected chickens with no TP. The genome copy number of MDV was also significantly higher in the brain tissues of the infected birds with clinical TP than those without TP. Comparative analysis between the two chicken lines showed that the expression levels of IL-6, IL-10, IFN-beta, IFN-gamma, IFN-lambda, IL-18, CD-18, and MHC I were significantly higher in the brain tissues of the birds from line 6-3 with TP than those of line 7-2 exhibiting clinical signs of TP. The expression pattern of these immune related genes suggests a possible immunological mechanism for the differential responses of the two chicken lines to MDV infection and exhibition of MDV-induced TP.