Novel criteria for the diagnosis of Marek's disease virus-induced lymphomas

Abstract

Several novel criteria have been tested to assist in the differential diagnosis of tumours induced by Marek's disease virus (MDV) from those induced by avian leukosis virus (ALV) and reticuloendotheliosis virus (REV). A collection of tumours induced by inoculation of specific strains of MDV, ALV and REV, alone or in combination, were tested for quantification of MDV DNA by real-time polymerase chain reaction, expression of the MDV oncogene Meq, expression of several cell markers associated with transformation (CD30, Marek's disease-associated surface antigen, and p53), and level of DNA methylation in the tumour cells. In addition, tissues latently infected with MDV and non-infected tissues were tested as controls. Tumours induced by MDV had about 10 2 -fold more copies of MDV DNA than either tissues latently infected by MDV or tumours induced by retrovirus in MDV-vaccinated chickens. Moreover, the MDV antigen Meq was consistently expressed in all MDV tumours but it could not be detected in tissues latently infected with MDV or in tumours induced by retrovirus in MDV-vaccinated chickens. Other markers studied were not specific for MDV and therefore had limited value for diagnosis. Nonetheless, some of these markers might have potential value in research as they will help to identify transformed cells.

A p53-dependent promoter associated with polymorphic tandem repeats controls the expression of a viral transcript encoding clustered microRNAs

“…Previous studies revealed that LAT and miRNA cluster 2 in GaHV-2 are abundantly expressed during the latency and lymphomagenesis stages of viral infection (Burnside et al 2006(Burnside et al , 2008Xu et al 2008). Although p53 is considered to be a major tumor repressor, it has been shown that nonmutated p53 is present in GaHV-2-induced lymphomas (Gimeno et al 2005). Further experiments are required to investigate the apparent contradiction between the production of native p53 and the development of lymphomas.…”

Relationship between Marek's disease virus load in peripheral blood lymphocytes at various stages of infection and clinical Marek's disease in broiler chickens

“…The number of MDV genome copies measured in this study is in broad agreement with recent reports (Baigent et al ., 2005;Gimeno et al ., 2005). Viral titres have been shown to be lower in PBL than spleen cells and feather follicle epithelium (Davidson & Borenshtain, 2003;Baigent et al ., 2005).…”

Homodimerization of Marek's Disease Virus-Encoded Meq Protein Is Not Sufficient for Transformation of Lymphocytes in Chickens

“…However, evaluation of effects of MeqGCN on cytolytic infection is difficult because Meq expression is not essential for early cytolytic infection (25). Meq is not always detected early in infection, and expression of Meq in vivo is variable and has been shown to depend on the virus strain and chicken line used (8,26). Since the FFE is the site of fully productive infection and source of horizontal transmission (4), we evaluated the role of Meq homodimers on transmission by IHC (Fig.…”