Location: Avian Disease and Oncology ResearchTitle: Identification of lymphoproliferative disease virus in wild turkeys (Meleagris gallopavo) in the United States Author
Submitted to: United States Animal Health Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/18/2012
Publication Date: 10/22/2012
Citation: Brown, J.D., Allison, A.B., Keel, K.M., Welch, T., Fadly, A.M. 2012. Identification of lymphoproliferative disease virus in wild turkeys (Meleagris gallopavo) in the United States. Proceedings for the 116th Annual Meeting of the United States Animal Health Association, October 18-October 24, 2012, Greensboro, North Carolina. 97-98. Interpretive Summary:
Technical Abstract: Viral-associated lymphoproliferative neoplasia in domestic poultry is caused by infection with a herpesvirus (Marek’s disease virus) or three species of retroviruses [Reticuloendotheliosis virus (REV), Avian leukosis/sarcoma virus, lymphoproliferative disease virus (LPDV)]. Previously, retroviral neoplasms reported in wild upland game birds in the United States have typically been associated with REV infection. Since 2009, LPDV, a virus previously believed to be exotic to the United States, has been identified in 10 wild turkeys (Meleagris gallopavo) submitted to the Southeastern Cooperative Wildlife Disease Study for diagnostic examination from six states, including West Virginia (n=5), North Carolina (n=1), Missouri (n=1), Georgia (n=1), and Arkansas (n=1). Infected turkeys were found dead or in moribund condition. Proviral sequences of LPDV were detected in various tissue samples from each turkey using PCR targeting a portion of the gag gene. Based on gross and microscopic lesions, lymphoproliferative disease associated with LPDV infection was determined to be the primary cause of mortality in five of the turkeys with proliferating mononuclear cells identified in various visceral organs and tissues, including skin, intestines, liver, kidneys, spleen, pancreas, lungs, adrenal glands, skeletal muscle, esophagus, heart, and air sacs. Other primary causes of morbidity and/or mortality were determined in the remaining five turkeys. To follow-up on these clinical cases, tissues collected from hunter-killed turkeys from multiple states were tested for LPDV, as described above, and additional positive turkeys were identified in Colorado (n=1) and South Carolina (n=36). Genetic comparisons of sequences obtained from tissues from all LPDV-positive turkeys demonstrated a high level of diversity, with nucleotide divergence ranging up to 15%. Notably, phylogenetic analysis of gag sequences from a subset of turkeys from South Carolina were shown to cluster independently from all other North American LPDV strains and formed a monophyletic group with the prototype Israeli strain, suggesting these viruses may represent an evolutionary bridge between the Old and New World viruses. The cases reported herein are novel as they represent the first reports of LPDV infection in wild turkeys and the first identification of LPDV in North America. Current research efforts are underway to better understand the epidemiology, natural history, and significance of this virus to wild and domestic galliforms, including 1) active surveillance of hunter-killed turkeys, 2) genetic characterization of North American strains, 3) experimental challenge studies in domestic turkeys, and 4) evaluation of LPDV replication in cell culture systems.