Marek's disease in turkeys: The induction of lesions and the establishment of lymphoid cell lines

Marek's Disease Virus in Commercial Turkey Flocks, Iran

Marek's disease is a significant illness in chickens and a potential threat to the poultry industry worldwide. Marek's disease virus (MDV) causes immunosuppression and lymphoproliferative disease in chickens, but the turkey is an unusual host for the virus, and tumors caused by MDV in turkeys are unique. This study sampled 15 asymptomatic commercial turkey flocks (five spleens from each flock) at slaughter. Gallid alphaherpesvirus 2 (GaHV-2) was identified by PCR of spleen samples of two flocks. A phylogenetic analysis of the Meq gene was also performed. Sequencing and phylogenetic analysis revealed that the turkey GaHV-2 had genetic similarity with GaHV-2 strains recently detected in the Iranian commercial layer and breeder turkey flocks. This is the first time MDV has been detected in turkey flocks of Iran, and therefore, further assays including experimental inoculation to demonstrate pathotype characteristics in vivo are needed.

Molecular characterization of a Marek's disease virus strain detected in tumour-bearing turkeys

Marek's disease (MD) is a lymphoproliferative disease caused by Gallid alphaherpesvirus 2 (GaHV-2), which primarily affects chickens. However, the virus is also able to induce tumours in turkeys, albeit less frequently than in chickens. This study reports the molecular characterization of a GaHV-2 strain detected in a flock of Italian meat-type turkeys exhibiting visceral lymphomas. Sequencing and phylogenetic analysis of the meq gene revealed that the turkey GaHV-2 has molecular features of high virulence and genetic similarity with GaHV-2 strains recently detected in Italian commercial and backyard chickens. GaHV-2 is ubiquitous among chickens despite vaccination, and chicken-to-turkey transmission is hypothesized due to the presence of broilers in neighbouring pens.RESEARCH HIGHLIGHTS A GaHV-2 strain from Italian turkeys was molecularly characterized.The turkey strain presented molecular characteristics of high virulence in its meq gene.The turkey strain was closely related to previously detected chicken strains.

Marek's disease in turkeys. I. A seven-year survey of commercial flocks and experimental infection using two field isolates

Marek's disease virus (MDV) causes immunosuppression and tumors in chickens, but the turkey is an unusual host for the virus, and tumors caused by MDV in turkeys are unique. We describe the prevalence of turkey tumors in Israel between 1993 and 2000, their molecular diagnosis by polymerase chain reaction (PCR), and the natural distribution of herpesvirus of turkeys (HVT). Most clinical cases with tumors in commercial turkeys were diagnosed as MDV. The reproduction of Marek's disease (MD) in turkeys by two turkey MDV strains, Ar and La, was analyzed, and it was shown that these strains can induce tumors in experimental trials. The severity of experimental disease differed from those features of the original outbreak, since a less severe disease was recorded.

Antibody directed against Marek's disease-associated tumor surface antigen can be eluted from Marek's disease tumor cells

Antibody directed against Marek's disease-associated tumor surface antigen (MATSA) was eluted from tumor cells of lymphomas and peripheral blood lymphocytes that were isolated from Marek's disease virus-infected chickens. Feather follicular Marek's disease virus (MDV) antigen could not be demonstrated with this antibody by indirect immunofluorescent (IF) staining. Monoclonal antibody directed against MATSA could completely block the activity of eluted antibody and vice versa. By indirect IF staining using eluted antibody and fluorescein isothiocyanate (FITC) labelled antichicken globulin conjugate. MATSA-bearing cells were detected in MDV infected and herpes virus of turkey (HVT) vaccinated birds. Blocking of immunoglobulin molecules present on B-cells by anti-chicken globulin is critical in this test.