DIAGNOSING LYMPHOPROLIFERATIVE DISEASE VIRUS IN LIVE WILD TURKEYS (MELEAGRIS GALLOPAVO) USING WHOLE BLOOD

Abstract

Lymphoproliferative disease virus (LPDV) is a retrovirus that infects wild and domestic turkeys ( Meleagris gallopavo ). The first cases of LPDV in the United States were diagnosed in 2009, and subsequent surveillance has revealed the virus to be widespread in wild turkey populations throughout the eastern half of the country. More research is needed to determine whether LPDV is having a negative effect on turkey populations, but progress has been impeded by the lack of a simple method for diagnosing the virus in living birds. Infected animals may appear asymptomatic, and diagnostics currently rely on tissue or bone marrow, which can be difficult to obtain. This study investigated the reliability of polymerase chain reaction (PCR) to detect LPDV in whole blood, compared with previous methods using buffy coat (concentrated white blood cells) and bone marrow. Paired samples of whole blood and buffy coat were collected from 137 live turkeys and paired samples of whole blood and bone marrow were collected from 32 turkeys postmortem. Compared with buffy coat, whole blood had 97% sensitivity and 100% specificity. When compared with bone marrow, whole blood had 100% sensitivity and 89% specificity. Both comparisons had a high degree of agreement using Cohen's kappa statistic. Based on these results, PCR of whole blood provides detection of LPDV in living birds that is on par with both buffy coat and bone marrow.

Galliformes and Columbiformes

“…Diagnosis of LD requires histological confirmation of neoplastic infiltrates in the skin or multiple organs. The most sensitive tissue for molecular detection of LPDV is bone marrow, but whole blood, visceral organs, and spleen can also be used (Alger et al, 2015;Thomas et al, 2015). The method of virus transmission is not known.…”

Prevalence of lymphoproliferative disease virus in wild turkeys (Meleagris gallopavo) in North Carolina

“…Additionally, we opportunistically collected tarsi from turkeys that were killed by motor vehicles and we worked with wildlife enforcement officers to collect tarsi from turkeys illegally killed by poachers. Methods for data collection and testing for samples collected followed those outlined by Alger et al (2015), with PCR testing for evidence of LPDV presence. We categorized turkeys by sex and age according to beard length, central tail feathers, and primary wing feather characteristics (Pelham and Dickson 1992).…”

“…We also suggest that wild turkey researchers increase the understanding of LPDV prevalence in older wild turkeys by investigating the infection status of adult turkeys for which exact age in years is known. Furthermore, because LPDV status can be determined via blood draws from live turkeys (Alger et al 2015), we encourage researchers to take advantage of opportunities where the LPDV status can be determined for individual turkeys at multiple times throughout life. Repeated measurements would provide insight into infection rates of adult birds and potentially offer better understanding into whether LPDV was affecting survival, habitat use, or reproduction.…”

Detecting lymphoproliferative disease virus in wild turkeys using cloacal swabs

“…We employed rocket nets to capture live wild turkeys from January through March 2018 and drew blood from the brachial vein into ethylenediaminetetraacetic acid (EDTA) collection tubes. We centrifuged the blood for 15 minutes at 2500 RPM to optimize collection of the buffy coat layer, which consists of the isolated white blood cells and is the standard antemortem sample type for LPDV detection (Alger et al 2015). For 2 (out of 85) samples, blood collection volume was low (approximately <1 mL) and, thus, we vortexed the collection tube and took a whole blood sample, which has been shown to yield results that are comparable to detection based on buffy coat alone (97% sensitivity and 100% specificity; Alger et al 2015).…”

“…We centrifuged the blood for 15 minutes at 2500 RPM to optimize collection of the buffy coat layer, which consists of the isolated white blood cells and is the standard antemortem sample type for LPDV detection (Alger et al 2015). For 2 (out of 85) samples, blood collection volume was low (approximately <1 mL) and, thus, we vortexed the collection tube and took a whole blood sample, which has been shown to yield results that are comparable to detection based on buffy coat alone (97% sensitivity and 100% specificity; Alger et al 2015). Hereafter, we refer to the whole blood and buffy coat samples collectively as blood.…”