Clinical materials: Since MD virus is cell associated the virus could be isolated from buffy coat cells from heparinised blood samples, or suspensions of lymphoma cells or spleen cells
Isolation systems: Chicken kidney cells or duck embryo fibroblasts are normally used for isolation. Chicken embryo fibroblasts are less sensitive for primary isolation. The cytopathic effects, termed plaques, appear within 3–5 days and can be enumerated at about 7–10 days. They also produce intranuclear inclusion bodies. SPF chickens can also be used.
Direct identification MD virus from clinical materials
The cell free MD viruses could be isolated from feather follicles in chicken kidney cells as mentioned above.
Polymerase chain reaction (PCR) is also used to identify MD virus from clinical materials. Further in this technique, the seroytpe could also be differentiated.
Demonstration of MATSA antigen by indirect fluorescent antibody test.
Agar gel immunodiffusion test: This test is employed most commonly to detect antibody. The test is conducted using glass slides coated with 1% agar in phosphate buffered saline containing 8% sodium chloride. Adjacent wells are filled with antigen or serum and these are incubated in a humid atmosphere at 37°C for 24 hours for diffusion to take place. The antigen used in this test is either disrupted MDV-infected tissue culture cells or an extract of feather tips, or skin containing feather tracts obtained from MDV-infected chickens.
Indirect fluorescent antibody test
Virus neutralization test
ELISA
Differential diagnosis: Marek’s disease should be differentiated from lymphoid leucosis and reticuloendotheliosis.