Marek's Disease in poultry industry

Can the Agar Gel Precipitin Test (diffusion test) and ELISA be used in screening vaccinated birds against Marek's disease outbreak?

No, the AGP and ELISA tests will cross react with antibodies generated by vaccine strains . Moreover, the presence of antibodies and even virus isolation does not necessarily indicate that there is an outbreak of MD

Thank you Schat for your response. Sir, which tests can be used for serotyping of Marek's disease virus serotype1, 2 and 3)? Can the use of ELISA, PCR, Immunohistochemistry etc be used?

Dear Professor Schatt, My backyard flock was exposed to MDV 4 years ago. At that time I had 10 chicks and 3 adults present with paralysis, and were euthanized. Recently, I've had 10 deaths in six months of chickens 4-7 years old. I'm sure some have died from other illnesses. But the 3 necropsies I had done were negative for MDV, but it appears that the chickens died from opportunistic bacteria mostly causing enteritis, and one with Aspergillosis. My questions are why have my 3 necropsied chickens test negative for MDV? Can MDV exposed chickens develop a sort of immunosuppression later in life? Thankyou, Karen Fletcher