Molecular Surveillance for Lymphoproliferative Disease Virus in Wild Turkeys (Meleagris gallopavo) from the Eastern United States.

Jesse M Thomas,Jamie E Phillips,Edward C Holmes,Elizabeth M Bunting,Andrew B Allison,Michael J Yabsley,Justin D Brown,Jonas Waldenström

doi:10.1371/journal.pone.0122644

Abstract

Lymphoproliferative disease virus (LPDV) is a poorly understood, oncogenic avian retrovirus of domestic turkeys that has historically been restricted to Europe and Israel. However, a recent study reported LPDV in multiple wild turkey diagnostic cases from throughout the eastern United States of America (USA). To better understand the distribution of LPDV in the eastern USA, we surveyed 1,164 reportedly asymptomatic hunter-harvested wild turkeys from 17 states for the presence of LPDV proviral DNA by PCR. In total, 564/1,164 (47%) turkeys were positive for LPDV. Wild turkeys from each state had a relatively high prevalence of LPDV, although statewide prevalence varied from 26 to 83%. Phylogenetic analysis revealed two major clades of LPDV in the USA, although one was at a low frequency suggesting restricted transmission, as well as significant clustering by state of isolation. To determine the best tissue to target for diagnostic purposes, liver, spleen, and bone marrow were tested from a subset of 15 hunter-harvested wild turkeys and 20 wild turkey diagnostic cases. Overall, bone marrow provided the highest level of detection for both hunter-harvested turkeys and diagnostic cases. The sensitivity of LPDV detection between tissues was not significantly different for diagnostic cases, but was for hunter-harvested birds. These results indicate that LPDV infection is common and widespread in wild turkey populations throughout the eastern USA, even without overt signs of disease.

Highlights

Neoplastic diseases of gallinaceous poultry can be non-infectious or induced by viruses
564 of 1,164 (47%) wild turkey samples were positive for Lymphoproliferative disease virus (LPDV) proviral DNA (Table 1)
In 2009, the first reported case of LPDV in both a wild bird and in North America was identified in a wild turkey in Arkansas diagnosed with lymphoproliferative disease [11]

Summary

Introduction

Neoplastic diseases of gallinaceous poultry can be non-infectious (i.e., spontaneous) or induced by viruses. Non-infectious neoplasms in poultry are sporadic in occurrence, typically affect older birds, and are of minor economic significance to the poultry industry [1]. Viral-induced neoplasms in gallinaceous poultry are most commonly caused by one of three viruses: (i) Marek’s disease virus type 1 (MDV), (ii) avian leukosis virus (ALV), and (iii) reticuloendotheliosis virus (REV). Marek’s disease virus is ubiquitous in domestic chicken populations throughout the world and is a significant source of economic losses due to mortality, condemnation, decreased production, and/or costs associated with control [1]. Since the introduction of vaccination of commercial poultry in the early 1970’s, mortality associated with MDV has dropped significantly; sporadic outbreaks still occur as new virulent viral strains emerge for which vaccines are not fully protective [1]

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