Viruses, Vol. 12, Pages 1048: The Emergence of a vv + MDV Can Break through the Protections Provided by the Current Vaccines

Viruses, Vol. 12, Pages 1048: The Emergence of a vv + MDV Can Break through the Protections Provided by the Current Vaccines Viruses doi: 10.3390/v12091048 Authors: Meng-ya Shi Min Li Wei-wei Wang Qiao-mu Deng Qiu-hong Li Yan-li Gao Pei-kun Wang Teng Huang Ping Wei Marek’s disease (MD) is an infectious malignant T-cell lymphoma proliferative disease caused by Marek’s disease virus (MDV). In recent years, the emergence of very virulent (vv) and/or very virulent plus (vv +) strains of MDV in the field has been suggested as one of the causes of vaccination failure. The pathogenicity of the MDV strain GX18NNM4, isolated from a clinical outbreak in a broiler breeder flock that was vaccinated with CVI988/Rispens, was investigated. In the vaccination-challenge test, GX18NNM4 was able to break through the protections provided by the vaccines CVI988 and 814. It also significantly reduced body weight gain and caused marked gross lesions and a large area of infiltration of neoplastic lymphocyte cells in the heart, liver, pancreas, etc. of the infected birds. In addition, the expressions of programmed death 1 (PD-1) and its ligand, programmed death ligand 1 (PD-L1), in the spleens and cecal tonsils (CTs) of the unvaccinated challenged birds were significantly increased compared to those in the vaccinated challenged birds, indicating that the PD-1/PD-L1 pathway is related to immune evasion mechanisms. The results showed that the GX18NNM4...
Source: Viruses - Category: Virology Authors: Tags: Brief Report Source Type: research