ARS | Publication request: MAREK'S DISEASE VACCINES--PAST, PRESENT AND FUTURE (CHICKEN VS VIRUS--A BATTLE OF THE CENTURIES)

Submitted to: International Marek's Disease Symposium Abstracts and Proceedings
Publication Type: Proceedings
Publication Acceptance Date: November 22, 2000
Publication Date: N/A

Technical Abstract: Early in the evolutionary history of the chicken, a relationship was forged between a species-specific herpesvirus and its host. Early data are lacking but we know that the relationship had become contentious by the onset of the 20th century and gradually dissolved into full scale war. As we now contemplate the 21st century, it is appropriate to consider whether chicken nor virus will ultimately prevail. The virus possesses formidable weapons including the ability to spread horizontally, persist in the host, survive in nature and mutate. The chicken has an armamentarium of defensive genes that determine disease resistance and immune response and in recent years has enlisted support from man who has helped increase the frequency of desirable traits through breeding and has exposed them to less virulent viral strains to induce protective immunity. However, man has also increased bird densities, added stress associated with high productivity and has promoted husbandry that provides the virus the opportunity to infect chickens at a very early age. The efforts of both parties to prevail in this conflict, each using its available weapons, is addressed along with predicted scenarios of how each party may ultimately win. New serotype 1 vaccine strains and the use of incompletely attenuated viruses represent new weapons that favor the chicken, at least in the short term. However, evidence for continued evolution of pathotypes along with the prospects of bioterrorism and the demise of animal biology favor the virus. A favorable outcome for the chicken will only be possible when scientists develop mutation stabilizing control strategies and the poultry industry underwrites the cost. Whatever the outcome, it will not likely be decided quickly.