title: Isolation and purification of Gallid herpesvirus 2 strains currently distributed in Japan.
abstract: Gallid herpesvirus 2 (GaHV-2) causes malignant lymphomas in chickens (Marek's disease, MD). Although MD is controlled through vaccination efforts, field isolates of GaHV-2 have increased in virulence worldwide and even cause MD in vaccinated chickens. GaHV-2 strains are classified into four categories (mild, virulent, very virulent and very virulent +) based on the virulence exhibited in experimental infection in unvaccinated or MD-vaccinated susceptible chickens. Although MD cases are sporadically reported in Japan, the recent field strains of GaHV-2 in Japan have not been characterized. During isolation of recent field strains by using primary chicken kidney cell cultures, a method classically used for GaHV-2 isolation, vaccine strains were simultaneously isolated. Therefore, it is necessary to separate vaccine strains to characterize the virulence and pathogenicity of the GaHV-2 strains currently distributed in Japan. In this study, we prepared cell suspensions from the spleens of MD-symptomatic chickens, inoculated day-old-chicks and isolated GaHV-2 strains by primary chicken kidney cell cultures at 2-3 weeks post inoculation. The isolated strains were passaged several times on chicken embryo fibroblast cells, and PCR analysis revealed that the isolated strains were not contaminated with vaccine strains. Moreover, the contaminant vaccine strains were completely removed by the purification of plaques observed in chicken kidney cells. These procedures are necessary to isolate GaHV-2 field strains from vaccine strains in order to carry out future studies to characterize these strains and glean insights into GaHV-2 virulence and pathogenicity.
authors.affiliation: Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Kita-18, Nishi-9, Kita-ku, Sapporo 060-0818, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Machida
authors.forename: Shiro
authors.initials: S
authors.lastname: Murata
authors.forename: Ayumi
authors.initials: A
authors.lastname: Matsuyama-Kato
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Isezaki
authors.forename: Akira
authors.initials: A
authors.lastname: Taneno
authors.forename: Eishi
authors.initials: E
authors.lastname: Sakai
authors.forename: Satoru
authors.initials: S
authors.lastname: Konnai
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ohashi
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002645:Chickens / Q000821:virology*; D008381:Herpesvirus 2, Gallid / Q000302:isolation & purification* / Q000472:pathogenicity; D007564:Japan / Q000453:epidemiology; D007668:Kidney / Q000166:cytology; D008380:Marek Disease / Q000821:virology; D022501:Marek Disease Vaccines; D016133:Polymerase Chain Reaction; D011201:Poultry Diseases / Q000821:virology*; D013154:Spleen / Q000821:virology; D014776:Virus Cultivation / Q000662:veterinary
chemical_list: D022501:Marek Disease Vaccines