title: Vaccine and oncogenic strains of gallid herpesvirus 2 contain specific subtype variations in the 5' region of the latency-associated transcript that evolve in vitro and in vivo.
abstract: Gallid herpesvirus 2 (GaHV-2) is the alphaherpesvirus responsible for Marek's disease (MD), a T-cell lymphoma of chickens. The virulence of the GaHV-2 field strain is steadily increasing, but MD is still controlled by the CVI988/Rispens vaccine. We tried to determine distinguishing traits of the CVI988/Rispens vaccine by focusing on the 5' end region of the latency-associated transcript (5'LAT). It includes a variable number of 60-bp tandem repeats depending on the GaHV-2 strain. By analyzing six batches of vaccine, we showed that CVI988/Rispens consisted of a population of 5'LAT molecular subtypes, all with deletions and lacking 60-bp tandem repeat motifs, with two major subtypes that probably constitute CVI988/Rispens markers. Serial passages in cell culture led to a substantial change in the frequency of CVI988/Rispens 5'LAT subtypes, with non-deleted subtypes harboring up to four 60-bp repeats emerging during the last few passages. Dynamic changes in the distribution of 5'LAT-deleted subtypes were also detected after infection of chickens. By contrast, the 5'LAT region of the oncogenic clonal RB-1B strain, which was investigated at every step from the isolation of the clonal bacmid RB-1B DNA to the isolation of the ovarian lymphoma cell line, consisted of non-deleted 5'LAT subtypes harboring at least two 60-bp repeats. Thus, vaccine and oncogenic GaHV-2 strains consist of specific populations of viral genomes that are constantly evolving in vivo and in vitro and providing potential markers for epidemiological surveys.
authors.affiliation: Equipe Transcription et Lymphome Viro-Induit (TLVI), UMR 7261 CNRS/Université François Rabelais de Tours, Parc de Grandmont, 37200, Tours, France.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Labaille
authors.forename: Adrien
authors.initials: A
authors.lastname: Lion
authors.forename: Elodie
authors.initials: E
authors.lastname: Boissel
authors.forename: Sascha
authors.initials: S
authors.lastname: Trapp
authors.forename: Venugopal
authors.initials: V
authors.lastname: Nair
authors.forename: Denis
authors.initials: D
authors.lastname: Rasschaert
authors.forename: Ginette
authors.initials: G
authors.lastname: Dambrine
mesh_terms: D000818:Animals; D002645:Chickens; D019143:Evolution, Molecular; D015967:Gene Expression Regulation, Viral / Q000502:physiology*; D014644:Genetic Variation; D008381:Herpesvirus 2, Gallid / Q000145:classification* / Q000235:genetics; D008380:Marek Disease / Q000517:prevention & control / Q000821:virology*; D013047:Specific Pathogen-Free Organisms; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D014764:Viral Proteins; D014765:Viral Vaccines