relation between infection of chickens with Marek's disease and the presence of precipitin antibodies

Precipitin antibodies passively transmitted to progeny from dams of a breeder flock (HWL) free of RIF and specific pathogens, were found in about 75% of the chicks during the first 10 days of life. Thereafter the number of chicks with antibodies decreased rapidly, with no antibodies detected after 18 days of age. The progeny of a defined breeder flock (HWL and line 7) were raised under strict isolation for 76 to 207 days without evidence of precipitin antibodies or other indications of MD. However, Marek's disease herpesvirus (MDHV) was recovered from progeny when new lots of 1-day-old chicks were introduced into the same quarters, initiating a multiple-brooding process. The procedure of isolating MDHV by direct culture of kidneys in test birds was found superior to isolation of the virus from blood or tissue in chick kidney cell (CKC) monolayers. Precipitin antibodies in the blood generally appeared 12 to 14 days after MDHV was isolated, and both virus and antibodies apparently persisted at the same time. Although the role of the precipitin antibody is not clear, there does not appear to be a relationship between the level of the gamma globulin and the titer of precipitin antibody. The gamma globulin fraction decreased while the precipitin antibody continued to rise after the 75th day of inoculation.