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United States Department of Agriculture

Agricultural Research Service


item Shaw, Gillian
item Gimeno, Isabel
item Witter, Richard
item Lee, Lucy
item Silva, Robert
item Fadly, Aly

Submitted to: Annual Merck Merial Veterinary Scholars Symposium
Publication Type: Proceedings
Publication Acceptance Date: 7/31/2003
Publication Date: 7/31/2003
Citation: Shaw, G., Gimeno, I.M., Witter, R.L., Lee, L.F., Silva, R.F., Fadly, A.M. 2003. New techniques for diagnosis of Marek's disease in chickens. Annual Merck Merial Veterinary Scholars Symposium. p. 105.

Interpretive Summary:

Technical Abstract: Avian lymphomas can be caused by different viruses such as herpesvirus (Marek's Disease Virus - MDV) and retroviruses (Reticuloendotheliosis Virus - REV and Avian Leukosis Virus - ALV). Economically, these viruses can be devastating by causing decreased production and loss of profit for the poultry industry. The gross lesions induced by the three viruses can appear similar making a definite diagnosis difficult. Currently, diagnosis is made based on histological aspects of the tumors, but the existence of mixed infections can mislead the diagnosis. The goal of this project is to establish a procedure to differentiate lymphomas caused by MDV from those caused by retroviruses (REV and ALV). A collection of tumor samples obtained within the last ten years was used in this study. Tumors included those from birds with single infections (MDV, ALV or REV) and multiple infections (MDV+ALV+REV). Control samples included tissues of MDV infected chickens with no tumors and those from uninfected chickens. The expression of one viral oncogene (meq) and two cellular markers (AV37 and MATSA), which have been associated with MDV tumors, were studied using immunohistochemistry. Real time PCR was used to quantify the MDV DNA load. Our results show that meq is consistently expressed in tumors caused by MDV but it is lacking in tumors caused by other etiological agents even when serotype 1 MDV vaccines were present. AV37 and MATSA were expressed at a higher level in MDV tumors than in other lymphomas, but expression was detected in most of the groups especially in the case of MATSA. A threshold was established for real time PCRs to differentiate between load of MDV DNA in tumors and infected tissues and between tumors caused by MDV and those induced by retroviruses (when mixed infections were present). This work thus presents useful criteria for a more accurate diagnosis of MDV. [Supported by NIH T35 Grant]

Last Modified: 10/15/2017
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