title: Deletion of the BAC sequences from recombinant meq-null Marek's disease (MD) virus increases immunosuppression while maintaining protective efficacy against MD.
abstract: Marek's disease virus (MDV) GX0101 is a field strain of MDV with a naturally occurring insertion of the reticuloendotheliosis virus (REV) long terminal repeat (LTR) fragment. Both copies of the meq gene were knocked out in the GX0101 bacterial artificial chromosome (BAC) clone to construct the recombinant virus SC9-1, resulting in a complete lack of pathogenicity and providing better protection against MD than CVI988/Rispens. In the present study, the BAC sequences in SC9-1 were removed using a cre-loxP system, and the virus termed SC9-2. SC9-2 showed a significant increase in replication in vitro and in vivo. There was a significant decrease in chicken weight, immune organ index, and antibody levels compared with those of SC9-1-inoculated chickens. The immune protection index of SC9-2 was similar to that of SC9-1, and the difference was not significant. The results of our studies demonstrate that the SC9-2 virus provides protection in specific pathogen free (SPF) chickens when challenged with a very virulent MDV rMd5, but it induces immunosuppressive effects in SPF chickens.
authors.affiliation: College of Veterinary Medicine, Shandong Agricultural University, Tai'an, Shandong, 271018, China.
authors.forename: S
authors.initials: S
authors.lastname: Su
authors.affiliation: College of Veterinary Medicine, Shandong Agricultural University, Tai'an, Shandong, 271018, China.
authors.forename: N
authors.initials: N
authors.lastname: Cui
authors.affiliation: Tengzhou Animal Husbandry and Veterinary Bureau, Tengzhou, Shandong, 277500, China.
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.affiliation: College of Veterinary Medicine, Shandong Agricultural University, Tai'an, Shandong, 271018, China.
authors.forename: P
authors.initials: P
authors.lastname: Sun
authors.affiliation: Institute of Animal Husbandry and Veterinary Science, Shanghai Academy of Agricultural Sciences, Shanghai, 201106, China.
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.affiliation: Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.affiliation: College of Veterinary Medicine, Shandong Agricultural University, Tai'an, Shandong, 271018, China. Electronic address: zzcuisdau@126.com.
authors.forename: Z
authors.initials: Z
authors.lastname: Cui
mesh_terms: D000818:Animals; D002645:Chickens; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics; D008381:Herpesvirus 2, Gallid / Q000235:genetics*; D007165:Immunosuppression Therapy / Q000662:veterinary*; D008380:Marek Disease / Q000276:immunology* / Q000821:virology; D011201:Poultry Diseases / Q000276:immunology* / Q000382:microbiology; D001356:Reticuloendotheliosis virus / Q000235:genetics; D013047:Specific Pathogen-Free Organisms; D020079:Terminal Repeat Sequences
keywords: BAC; Marek's disease virus; immunosuppression; meq-null; protective efficacy