A Simple in vitro Differentiation between Turkey Herpesvirus and Marek's Disease Virus

Abstract

The growth and plaque formation by turkey herpesvirus (HVT) amd Marek's disease herpesvirus (MDHV) were examined in QT35 cells, a continuous fibroblast cell line derived from chemically induced tumors of Japanese quail. HVT grew and formed plaques consistently in QT35 cells when inoculated with cell-culture-propagated virus or peripheral mononuclear leukocytes (PML) from chickens that had been inoculated with HVT. Both oncogenic and nononcogenic strains of MDHV, however, failed to grow and induced neither plaques nor cytopathic effects in QT35 cells, whether inoculated with cell-culture-grown virus or heavily infected PML. When PML from chickens infected with both HVT and MDHV were assayed, only HVT plaques had developed, despite the presence in the inocula of high levels of MDHV with less HVT. The QT35 cell line provides a simple in vitro system for differentiating between HVT and MDHV and for selective isolation and identification of HVT from chickens infected with both HVT and MDHV.

Efficient Marek's disease virus (MDV) and herpesvirus of turkey infection of the QM7 cell line that does not contain latent MDV genome

“…These results are in agreement with an earlier report that MDV genes were undetectable in QM7 cells in Southern blot analysis (Schumacher et al, 2000). In addition, QT35 cells were reported to be resistant to MDV infection (Cho, 1981). This is consistent with QT35 cells harbouring latent MDV genome.…”

“…The cell morphology and growth characteristics of QM7 are very distinct from those of QT6 and QT35 cells, according to the reports above. QT35 cells were also previously shown to be resistant to MDV infection (Cho, 1981), consistent with subsequently finding the presence of latent MDV genome in these cells (Yamaguchi et al, 2000;Majerciak et al, 2001). Schumacher et al (2000Schumacher et al ( , 2001Schumacher et al ( , 2002 reported that constitutive expression of MDV gE protein in QM7 cells was required to support sufficient growth of MDV.…”

“…A close relative, Gallid herpesvirus 3 (MDV-2) consists of non-oncogenic chicken viruses. A third relative, herpesvirus of turkeys (HVT; also named Meleagrid herpesvirus 1, MDV-3) includes avirulent turkey viruses that are capable of replication in chickens (Cho, 1981;Osterrieder et al, 2006;Davison, 2010;Parvizi et al, 2010;Nair, 2013;Zelník et al, 2013).…”

“…In addition to chicken embryo fibroblast (CEF) cells, other primary avian cells that have been used to grow MDV include duck embryo fibroblast (DEF) cells, chicken kidney cells and chicken embryo kidney cells. QT35, a chemically transformed quail cell line that supports the growth of MDV-2 and HVT (Cho, 1981), was also used for vaccine production. However, virulent MDV was rescued from HVT-infected QT35 cells due to the presence of latent MDV genome in the QT35 cells (Yamaguchi et al, 2000;Majerciak et al, 2001).…”

Transactivation of Latent Marek's Disease Herpesvirus Genes in QT35, a Quail Fibroblast Cell Line, by Herpesvirus of Turkeys

“…These cells lines are free of avian retroviruses, but the presence of MDV in these cell lines has not been examined. QT35 cells are often used for virus propagation and are susceptible to infection with a wide range of avian viruses, including avian leukosis virus (ALV) subgroups C, E, and F and HVT (13,30) but not serotype 1 MDV (12). In this paper, the presence of MDV genes in QT35 cells, the subsequent rescue of a herpesvirus from these cells, and the expression of transcripts of MDV genes associated with latency and/or transformation in these cells are reported.…”