Molecular detection of Marek's disease virus antigen A in fowls infected with Marek’s disease

Marek’s disease (MD) is an important cause of lymphoproliferative lesions in chickens and is caused by a virus belonging to herpesvirus[1,2]. This virus consists of three serotypes. Serotype 1 is oncogenic MD virus (MDV), serotype 2 is nononcogenic of MDV while serotype 3 is herpesvirus of turkeys (HVT) virus[3]. All poultry races being farmed are sensitive to this disease[4]. The disease is spread via inhalation of aerosol droplets in poultry farm. Infection starts by the phagocytes in respiratory system and then the virus spreads to lymphatic tissues[5]. Within some weeks, B lymphocytes appear as tumor in the body[2]. MD can occur in 4 different forms: neural (nerve), cutaneous (skin), visceral (internal-organ) and ocular (eye) forms[6]. Even after vaccination, infection in the flock results in considerable damages. Diagnosis of MD disease is based on clinical signs and pathological changes (gross and microscopic observation). Early detection of Marek’s infection is crucial for devising strategies for control of possible outbreaks. In most of the studies, disease lesions are reported at older age. Under field conditions, determination of the exact incubation period under farm conditions is difficult. Chronic symptoms have also been reported in 3-4 week-old pullets, and in acute disease, the disease symptoms is observed after 8-9 weeks. In these cases, determining the time and infection conditions is very difficult[1]. In 1991, some researchers associated the factor of the disease with infectious multiple sclerosis or neural sclerosis in human beings[7]. The pathogen is a cell-associated herpesvirus and there is evidence regarding the isolation of this virus from feather follicle epithelium of infected chicks and this herpesvirus is spread via feather follicle epithelium[4]. The global vaccination of commercial bird flocks in the past 30 years reduced MD disease considerably all over the world however, dispersed epidemics have been reported in commercial flocks[2]. Therefore, rapid and exact diagnosis methods of MD and detection of pathogenic MDV strains are of great importance. Diagnosis of MD disease has been based on viral isolation, serological and molecular techniques. PCR is showed to be a valuable and rapid tool for diagnosis of animal and human diseases[8-14]. The present study aimed to detect MDV in ARTICLE INFO ABSTRACT