Submitted to: World Veterinary Poultry Association
Publication Type: Abstract Only
Publication Acceptance Date: August 18, 1997
Publication Date: N/A
Technical Abstract: Most neoplasia of lymphoid and other hematopoietic cells in commercial poultry is caused by viruses which belong to one of four distinct groups. Marek's disease virus (MDV) is an oncogenic herpesvirus. Avian leukosis virus (ALV), reticuloendotheliosis virus (REV) and lymphoproliferative disease (LPD) are oncogenic retroviruses. Each group is distinguished by nucleic acid type, molecular structure, antigenicity, epidemiology, host range and other characteristics. However, most of these viruses have in common a unique ability to persist, both in the host and in the ecosystem. In addition, the virus-host relationships for several members of the group have demonstrated a propensity to evolve with time, creating new dilemmas for diagnosis and control. A focus on these common properties of avian tumor viruses will be used to address a number of current issues with individual pathogens of economic importance. Issues of primary concern include (1) the evolution of MDV towards greater virulence with concomitant reduction of vaccine efficacy and expansion of host range, (2) the emergence of subgroup J ALV as a major pathogen in meat-type breeder stocks, and (3) the increasing prevalence of REV and its evolving role as a pathogen in chickens and turkeys.