In the present study, a field isolate of virulent Marek's disease virus (vMDV) was isolated in chicken embryo fibroblast (CEF) culture from the infected peripheral blood cells of affected birds and compared with HVT strain FC 126 in CEF. MDV detection in infected CEF coverslips was carried by Immunofluorescent test (IFT), Immunoperoxidase test (IPT) and May- Grunwald Giemsa (MGG) staining at different time intervals. By IFT, the specific intranuclear fluorescence in vMDV infected CEF in the form of foci of fluorescing rounded cells was observed around 5–7 days, whereas in HVT infected cells, it was seen within 48–72 hrs post-infection (PI). The viral antigens were also detected as above by IPT in the form of brown coloured characteristic deposits. Characteristic eosinophilic intranuclear inclusion bodies were detected by MGG staining in the infected CEF and appeared after 72 hrs PI in vMDV infected CEF as compared to within 4872 hrs in HVT infected CEF. Analysis of CEF infected with vMDV and HVT by SDS-PAGE revealed four major virus specific proteins having molecular weight of 160 KD, 100 KD, 79 KD and 61 KD. Based on these findings and the presence of virus specific proteins it is possible to detect vMDV in infected cells.
