Analysis of the evolution and transmission dynamics of the field MDV in China during the years 1995-2020, indicating the emergence of a unique cluster with the molecular characteristics of vv plus MDV that has become endemic in southern China
Analysis of the evolution and transmission dynamics of the field MDV in China during the years 1995-2020, indicating the emergence of a unique cluster with the molecular characteristics of vv plus MDV that has become endemic in southern China
复制标题
DOI：
10.1111/tbed.13965
复制
发表时间：
2021-04-27
影响因子：
4.3
通讯作者：
Wei, Ping
中科院分区：
文献类型：
--
作者：
Deng, Qiaomu;Shi, Mengya;Wei, Ping
马立克氏病（MD）继续威胁着世界家禽业的可持续性。本研究分析了1964-2020年间分离的220株MDV的meq基因序列，其中50株来自本组，170株来自GenBank。利用系统发育树、氨基酸突变筛选、进化研究和传播动力学进行了分析。所有菌株分为2个聚类（聚类1和聚类2），聚类1包括轻度毒株、疫苗毒株和外源毒力毒株，聚类2以中国野毒株为主。研究发现，1995-2020年聚类2中的中国田间菌株可能起源于20世纪80年代，这些菌株的遗传多样性估计经历了2005-2007.5和2015-2017两个生长阶段。病毒系统地理学鉴定出中国第2群田间菌株的3个主要地理省区：东北地区（吉林、辽宁和黑龙江）、中东部地区（河南、山东和江苏）和南部地区（广西、广东和云南）。东北菌株向中东部鸡群传播，并进一步由广西向广东传播。南方菌株在2017-2020年间同时出现A88T和Q93R突变，具有vv+ MDV的分子特征，也比北方菌株晚。总体而言，近年来中国南方第2群的中国田间菌株发展迅速。广西省已成为这些病毒的中心，南部地区的鸡群一直面临着新出现的vv+ MDV的不利影响。
Marek's disease (MD) continues to threaten the sustainability of the world poultry industry. In this study, the sequences of the meq gene of 220 MDV strains isolated during the years 1964-2020 were analysed, including 50 from our group plus 170 isolates from the GenBank. Analyses, using phylogenetic trees, amino acid (aa)-mutation screening, evolutionary studies and transmission dynamics were all performed. All strains were divided into two clusters (Clusters 1 and 2), and Cluster 1 includes the mild strains, the vaccine strains and the foreign virulent strains, while Cluster 2 was dominated by the Chinese field strains. Our study identified that the Chinese field strains in Cluster 2 during the years 1995-2020 likely originated in the 1980s from abroad, and the estimated genetic diversity of these strains experienced two growth phases in the years 2005-2007.5 and 2015-2017. Viral phylogeography identified 3 major geographic provincial regions for the Chinese field strains of Cluster 2: the Northeastern Region (Jilin, Liaoning and Heilongjiang), the East-central Region (Henan, Shandong and Jiangsu) and the Southern Region (Guangxi, Guangdong and Yunnan). The spread of Northeastern strains to East-central chicken flocks and the further spread from Guangxi to Guangdong are strongly indicated. The emergence of the mutations A88T and Q93R together in the Southern strains during the years 2017-2020 with molecular characteristics of vv+ MDV were also found later than those in the Northern strains. Overall, the Chinese field strains in Cluster 2 in southern China in recent years have been rapidly evolving. Guangxi Province has become an epicentre for these viruses and the chicken flocks in the Southern region have been facing the adverse effects of the emerging vv+ MDV.