USPOULTRY and the USPOULTRY Foundation have announced the completion of a funded research project at the USDA Agriculture Research Service in East Lansing, MI, in which researchers found that the virulence of Marek’s disease virus may have plateaued. The project is part of the Association’s comprehensive research program encompassing all phases of poultry and egg production and processing. A brief summary of the completed project is shown below.

The project summary is as follows:
Project #F051: Pathotyping of Current Marek’s Disease Virus Field Strains and Identification of Sequence Variants to Predict Virulence

(Dr. John Dunn and Dr. Hans Cheng, Avian Disease and Oncology Laboratory, USDA Agricultural Research Service, East Lansing)

Researchers at the USDA Avian Disease and Oncology Laboratory recently completed a project that focused on the continued evolution of Marek’s disease virus (MDV). The disease causes tumors in chickens, has a long history of continuous evolution toward increased virulence in the field, which has required the continued development of more effective vaccines.


Dr. Dunn has completed the first survey of current MDV field viruses since 1997 and found, surprisingly, that the virulence of MDV in the U.S. poultry industry may have plateaued. He was not able to find MDV from current field cases that were any more virulent than viruses from 20 years ago. This is good news for the industry and may indicate that current management and vaccine programs have had a big positive impact.A complete report, along with information on other Association research, may be obtained by going to USPOULTRY’s website,