Detection of MDV Very Virulent Strain by Polymerase Chain Reaction and Analysis of its Meq Gene

Detection of MDV Very Virulent Strain by Polymerase Chain Reaction and Analysis of its Meq Gene

In this study, virus isolation, polymerase chain reaction (PCR) detection, sequencing and animal test were used to detect the clinical case of chickens infected with Marek's disease (MD). Pathologic changes with tumor lesions could be found on the liver, kidney and spleen of the infected chickens. Results of the virus isolation, PCR detection and Meq gene sequencing showed that the clinical case was caused by Marek's disease virus (MDV). The MDV isolate JZ2014 had Meq amino acid homology at 96.8-99.1% with 11 MDV reference strains. None of the vaccination with seven types of vaccines could completely protect the immunized chickens against JZ2014. The highest mortality was 70.3% in sham vaccine group. The lowest mortality was 23.0% in CVI988+SB1+HVT immunized group. The results indicated that the detected MDV JZ2014 could be a vvMDV strain, and the emergence of vv MDV was a significant problem for the poultry industry in China.