Marek's Disease. Dr. Karel A. Schat (Cornell University)

Dear Professor Schat, Thank you very much really for this nice piece of information. I am always your admirer as one who did his Msc thesis work on Chicken Anemia in UPM, Malaysia under Prof. Abdul Rahman Omar.

Dear Professor Dr. Karel, thank very much for you are one of those who have worked a lot on Marek's disease. MD is my field of interest. Kindly respond to me on 1. which test can be used for serotyping of MDV? can ELISA, PCR etc be used? 2. What is the maternal antibody in chicks derived from hens vaccinated against MD? 3. Very importantly, what is the effect of vaccinating a day old chick with maternal antibody? Jwander Luka

Dear Jwander Luka: Serotyping of MDV can be done by immunofluorescence or immunohistochemistry if you have the virus in cell culture using monoclonal antibodies. If DNA is available PCR can be used with serotype-specific primers. ELISA is used for serology to detect antibodies, but is in general not serotype specific. Matrenal antibodies will be present against serotype one by exposure to field strains or serotype 1 vaccines (e.g., Rispens vaccine), serotype 2 by field exposure or vaccination (e.g., SB-1) and if vaccinated with HVT to seroptype 3. Maternal antibodies have little effect on vaccination as long as cell-associated vaccines are used. If HVT maternal antibodies are present it will affect vaccination with cell-free HVT.

Thank you very much Prof. I still need clarification; 1.Under FIELD CONDITIONS in layers, can HVT maternal antibodies be present in chicks hatched? 2. The maternal antibody derived due to MDV in chicks, can it be IgG, IgB etc? Once more, thank you Prof.

Question 1: Only if the parent flock was vaccinated with HVT Question 2: The only antibodies in chickens are IgG (also called IgY), IgM and IgA. maternal antibodies are always IgG. Small amounts of IgA and IgM are present in the albumen and can be found in the newly hatched chicken, but these antibodies are of little relevance and not considered as maternal antibodies.