Marek's disease virus is an evolving pathogen, acquiring virulence in
response to increasingly effective vaccines. Although vaccine efficacy
is generally good, industry has placed a high priority on more effect
ive products. The search for better vaccines has been conducted mainly
in the arena of molecular biology, and has been thus far disappointin
g. Various conditions prevail that currently limit the potential to de
velop suitable long-term solutions. A new paradigm based on reduction
of early exposure, multiple levels of host resistance, and improved co
operation among stakeholders is proposed for consideration.