2.1 Sample collection
Tissue samples were collected between 2017 and 2018 from 13 flocks of different layer/ broiler parent lines/breeds maintained at ICAR-Directorate of Poultry Research (DPR), Hyderabad, India. The parent flocks were used in the production of layer/ broiler or dual type-colored varieties suitable for backyard poultry rearing. All the flocks were vaccinated with HVT on day old at in-house hatchery. Deceased birds from different flocks presented for necropsy showed MD specific lesions like enlargement of liver, spleen and visceral tumors etc. All tumor-associated organs including liver, spleen, kidney, proventriculus and sciatic nerve were collected from MD suspected birds in 10% neutral buffered formalin for histopathological examination. Another set was collected and kept frozen at -20˚C until use for DNA extraction and subsequent use in PCRs. Sample details of the present study are provided in supplementary table 1.