Molecular detection of Marek,s virus in backyard fowl with nodular lesions in visceral organs

Marek,s disease (MD) is one of the major immunosuppressive diseases in the poultry breeding industry, which can cause lymphoproliferative lesions in various visceral organs. Early identification of the disease in laying farms will prevent the cost of treatment and allows prompt decision-making on control measures and bio-security against the disease. In this respect, for detection of Marek,s disease virus (MDV) in nodular lesions of visceral organs of backyard fowls and tissue tropism of MDV, 50 samples were collected from suspected cases of Marek,s disease (MD). The samples were prepared from various tissues with and without gross nodular lesions. After DNA extraction from tissue samples, a 314-bp fragment with specific primers was amplified using PCR test to identify the infected cases and the tissue distribution of the antigen-A gene. In addition, 434 bp fragment of tandem repeat were also amplified by the use of a specific primer for the purpose of differentiation of pathogenic strains from non-pathogens. The results showed that in all cases infected with the MDV, in the tumorigenic stage, the gene that codes for antigen A can be detected in tissues with and without lesions. In addition, all positive samples belong to pathogenic strains. Therefore, in the tumorigenic stage of the MD, in spite of the presence or absence of macroscopic symptoms in the carcass of birds, the antigen-A gene of MDV can be detectd in all tissues.