title: Insertion of reticuloendotheliosis virus long terminal repeat into the genome of CVI988 strain of Marek's disease virus results in enhanced growth and protection.
abstract: Marek's disease (MD) is a lymphoproliferative disease of chickens caused by serotype 1 MD virus (MDV). Vaccination of commercial poultry has drastically reduced losses from MD, and the poultry industry cannot be sustained without the use of vaccines. Retrovirus insertion into herpesvirus genomes is an efficient process that alters the biological properties of herpesviruses. RM1, a virus derived from the virulent JM strain of MDV, by insertion of the reticuloendotheliosis (REV) long terminal repeat (LTR), was attenuated for oncogenicity but retains properties of the parental virus, such as lymphoid organ atrophy. Here we show that insertion of the REV LTR into the genome of vaccine strain CVI988 resulted in a virus (CVRM) that replicated to higher levels than parental CVI988 in cell culture and that remained apathogenic for chickens. In addition, CVRM showed protection indices similar or superior to those afforded by CVI988 virus in laboratory and field protection trials, indicating that it could be developed as a safe and efficacious vaccine to protect against very virulent plus MDV.
authors.affiliation: College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA.
authors.forename: Blanca
authors.initials: B
authors.lastname: Lupiani
authors.forename: Lucy F
authors.initials: LF
authors.lastname: Lee
authors.forename: K S
authors.initials: KS
authors.lastname: Kreager
authors.forename: Richard L
authors.initials: RL
authors.lastname: Witter
authors.forename: Sanjay M
authors.initials: SM
authors.lastname: Reddy
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D002645:Chickens; D005260:Female; D016679:Genome, Viral; D008381:Herpesvirus 2, Gallid / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity* / Q000502:physiology; D008297:Male; D008380:Marek Disease / Q000821:virology*; D022501:Marek Disease Vaccines / Q000235:genetics / Q000276:immunology*; D016254:Mutagenesis, Insertional; D016133:Polymerase Chain Reaction / Q000662:veterinary; D011201:Poultry Diseases / Q000821:virology*; D017986:Reticuloendotheliosis Viruses, Avian / Q000235:genetics; D020079:Terminal Repeat Sequences; D014614:Vaccines, Synthetic / Q000235:genetics / Q000276:immunology; D014779:Virus Replication
chemical_list: D022501:Marek Disease Vaccines; D014614:Vaccines, Synthetic