Despite reliance on the need to continually prepare fresh cultures of chick
embryo fibroblasts (CEFs) to make Marek's disease (MD) vaccines, MD vaccin
es an the most widely used vaccines in the poultry industry Preparation of
CEF's accounts for approximately 40% of the costs associated with producing
MD vaccines. A significant reduction in MD vaccine production costs could
be realized ifa continuous cell lines were available for MD vaccine product
ion. Recently, we reported development and characterization of a cell line
system (OCLTM) that supports growth and replication of oncogenic serotype 1
Marek's disease virus (MDV). Here we report development of three cell line
systems for production of MD vaccine. These cell lines support the growth
and replication of attenuated serotype 1 MDV (CV1-OCTM), serotype 2 MDV (SB
1OCLTM) and serotype 3 MDV (HVT-OCLTM). MDV is maintained in a stable state
in the OCLTM cells and the infected cells can be continuously grown. The v
accines made from these cell lines are safe and protect White Leghorn chick
ens against challenge with very virulent serotype 1 MDV, similar to traditi
onal vaccines made from CEF cells. These cell line systems can significantl
y reduce the costs associated with MD vaccine production. Furthermore, the
increased stability of MDV and the potential for positive selection of reco
mbinant MDV suggest that OCLTM will be ideal for production of more effecti
ve MDV vaccines using recombinant DNA technology.