title: Deletion of the Meq gene significantly decreases immunosuppression in chickens caused by pathogenic Marek's disease virus.
abstract: BACKGROUND
  Marek's disease virus (MDV) causes an acute lymphoproliferative disease in chickens, resulting in immunosuppression, which is considered to be an integral aspect of the pathogenesis of Marek's disease (MD). A recent study showed that deletion of the Meq gene resulted in loss of transformation of T-cells in chickens and a Meq-null virus, rMd5ΔMeq, could provide protection superior to CVI988/Rispens.
  
  
  RESULTS
  In the present study, to investigate whether the Meq-null virus could be a safe vaccine candidate, we constructed a Meq deletion strain, GX0101ΔMeq, by deleting both copies of the Meq gene from a pathogenic MDV, GX0101 strain, which was isolated in China. Pathogenesis experiments showed that the GX0101ΔMeq virus was fully attenuated in specific pathogen-free chickens because none of the infected chickens developed Marek's disease-associated lymphomas. The study also evaluated the effects of GX0101ΔMeq on the immune system in chickens after infection with GX0101ΔMeq virus. Immune system variables, including relative lymphoid organ weight, blood lymphocytes and antibody production following vaccination against AIV and NDV were used to assess the immune status of chickens. Experimental infection with GX0101ΔMeq showed that deletion of the Meq gene significantly decreased immunosuppression in chickens caused by pathogenic MDV.
  
  
  CONCLUSIONS
  These findings suggested that the Meq gene played an important role not only in tumor formation but also in inducing immunosuppressive effects in MDV-infected chickens.
authors.affiliation: Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100193, PR China.
authors.forename: Yanpeng
authors.initials: Y
authors.lastname: Li
authors.forename: Aijun
authors.initials: A
authors.lastname: Sun
authors.forename: Shuai
authors.initials: S
authors.lastname: Su
authors.forename: Peng
authors.initials: P
authors.lastname: Zhao
authors.forename: Zhizhong
authors.initials: Z
authors.lastname: Cui
authors.forename: Hongfei
authors.initials: H
authors.lastname: Zhu
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D001772:Blood Cell Count; D002645:Chickens; D002681:China; D019084:Fluorescent Antibody Technique, Indirect; D017353:Gene Deletion; D008381:Herpesvirus 2, Gallid / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D007108:Immune Tolerance / Q000276:immunology*; D008380:Marek Disease / Q000276:immunology* / Q000473:pathology / Q000821:virology*; D016019:Survival Analysis; D013601:T-Lymphocytes / Q000821:virology; D014779:Virus Replication / Q000235:genetics
chemical_list: D000914:Antibodies, Viral