title: A Chinese Variant Marek's Disease Virus Strain with Divergence between Virulence and Vaccine Resistance.
abstract: Marek's disease (MD) virus (MDV) has been evolving continuously, leading to increasing vaccination failure. Here, the MDV field strain BS/15 was isolated from a severely diseased Chinese chicken flock previously vaccinated with CVI988. To explore the causes of vaccination failure, specific-pathogen free (SPF) chickens vaccinated with CVI988 or 814 and unvaccinated controls were challenged with either BS/15 or the reference strain Md5. Both strains induced MD lesions in unvaccinated chickens with similar mortality rates of 85.7% and 80.0% during the experimental period, respectively. However, unvaccinated chickens inoculated with BS/15 exhibited a higher tumor development rate (64.3% vs. 40.0%), but prolonged survival and diminished immune defects compared to Md5-challenged counterparts. These results suggest that BS/15 and Md5 show a similar virulence but manifest with different pathogenic characteristics. Moreover, the protective indices of CVI988 and 814 were 33.3 and 66.7 for BS/15, and 92.9 and 100 for Md5, respectively, indicating that neither vaccine could provide efficient protection against BS/15. Taken together, these data suggest that MD vaccination failure is probably due to the existence of variant MDV strains with known virulence and unexpected vaccine resistance. Our findings should be helpful for understanding the pathogenicity and evolution of MDV strains prevalent in China.
authors.affiliation: Division of Avian Immunosuppressive Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China. sgrshenhua@hotmail.com.
authors.forename: Guo-Rong
authors.initials: GR
authors.lastname: Sun
authors.affiliation: Division of Avian Immunosuppressive Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China. zhyp_77@hvri.ac.cn.
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Zhang
authors.affiliation: Division of Avian Immunosuppressive Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China. lv6739533@163.com.
authors.forename: Hong-Chao
authors.initials: HC
authors.lastname: Lv
authors.affiliation: Division of Avian Immunosuppressive Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China. 1105296187@qq.com.
authors.forename: Lin-Yi
authors.initials: LY
authors.lastname: Zhou
authors.affiliation: Division of Avian Immunosuppressive Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China. cuihy@hvri.ac.cn.
authors.forename: Hong-Yu
authors.initials: HY
authors.lastname: Cui
authors.affiliation: Division of Avian Immunosuppressive Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China. ylg@hvri.ac.cn.
authors.forename: Yu-Long
authors.initials: YL
authors.lastname: Gao
authors.affiliation: Division of Avian Immunosuppressive Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China. qxl@hvri.ac.cn.
authors.forename: Xiao-le
authors.initials: XL
authors.lastname: Qi
authors.affiliation: Division of Avian Immunosuppressive Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China. yqw@hvri.ac.cn.
authors.forename: Yong-Qiang
authors.initials: YQ
authors.lastname: Wang
authors.affiliation: Division of Avian Immunosuppressive Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China. likaihvri@163.com.
authors.forename: Kai
authors.initials: K
authors.lastname: Li
authors.affiliation: Division of Avian Immunosuppressive Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China. gaoli0820@163.com.
authors.forename: Li
authors.initials: L
authors.lastname: Gao
authors.affiliation: Division of Avian Immunosuppressive Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China. panqing20050101@126.com.
authors.forename: Qing
authors.initials: Q
authors.lastname: Pan
authors.affiliation: Division of Avian Immunosuppressive Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China. xmw@hvri.ac.cn.
authors.forename: Xiao-Mei
authors.initials: XM
authors.lastname: Wang
authors.affiliation: Division of Avian Immunosuppressive Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China. liucj93711@hvri.ac.cn.
authors.forename: Chang-Jun
authors.initials: CJ
authors.lastname: Liu
mesh_terms: D000818:Animals; D002645:Chickens; D002681:China; D025922:Mardivirus / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification* / Q000472:pathogenicity; D008380:Marek Disease / Q000276:immunology* / Q000517:prevention & control / Q000821:virology*; D017211:Treatment Failure; D014765:Viral Vaccines / Q000276:immunology*; D014774:Virulence
chemical_list: D014765:Viral Vaccines
keywords: Marek’s disease virus; evolution; pathogenicity; vaccination failure; vaccine efficacy; virulence