DefinePK

Abstract

ABSTRACT Marek’s disease (MD), one of the most important avian immunosuppressive and neoplastic diseases, causes enormous economic losses in China. In 2023, seven 3-month-old chickens were determined to be infected with Marek’s disease virus (MDV) by histopathological examination, polymerase chain reaction (PCR), and gene sequencing. All of them originated from chicken flocks in JuRong (Jiangsu, China) and were immunized with the CVI988/Rispens (CVI988) vaccine. The novel MDV strain identified in these chickens was named JuRong 2023 and was isolated from feather follicle samples. Sequence analysis revealed that the Meq gene was most closely related to the SD-2012 strain, which was detected in Shandong Province. Furthermore, compared with the reference strain CVI988, the amino acid sequence of JuRong 2023 had mutations at positions 71, 80, 115, 176, 217 and 326, which may affect the function of the virus. Constant surveillance of newly isolated field strains in China is essential to evaluate the immune protection efficacy of different MD vaccines.