Detection of Pathogenic Marek's Disease Virus by Dot Blot Hybridization and PCR in Commercial Chickens in China

Marek's Disease Virus (MDV) is an oncogenic herpesvirus that causes various clinical syndromes in chickens which lead to huge economic losses for poultry industry. Compared with virulent MDV (vMDV) strains it was found that the vaccine strain CVI988 had a 5 bp deletion in the bi-directional promoter region in the genome of MD V. Based on the deletion, researchers developed a Polymerase Chain. Reaction (PCR) for the rapid identification of vMDV strains from vaccine CVI988 strain. In the present study, the sensitivity and specificity of different methods including PCR, virus isolation and dot blot hybridization for detecting MDV were compared. The results showed that PCR and dot blot hybridization assays were comparable in sensitivity to virus isolation and there were good correlations in positive results among the three techniques. In addition, the PCR assay similar with virus isolation was specific enough to identify CVI988 vaccine strain from vMDV. In company with PCR, the dot blot hybridization with the probe of pp38 gene labeled with digoxigenin were used to monitor the vMDV infection in commercial chicken flocks in China. The data demonstrated that MDV were widespread in. commercial chickens in China and the combination of dot blot hybridization and PCR assay was useful for screening for wild vMDV strains infection in chickens.