To help improve the control of Marek’s disease, veterinary medical officer John Dunn and his team at the Agricultural Research Service Avian Disease and Oncology Laboratory in East Lansing, Michigan, analyzed Marek’s disease genomes to find out which genes are mostly associated with virulence.
Marek’s disease, a highly contagious viral disease caused by a herpesvirus, is a constant threat to poultry worldwide. It is also one of the most preventable diseases with vaccination. However, while vaccines prevent poultry from becoming sick with symptoms of the virus, they do not prevent virus spread and mutation, considered the main reason for increased virus virulence, or severity, in field strains in U.S. commercial flocks.
John Dunn and his team sequenced DNA from 70 virus strains, collected over the years from across the United States, and identified significant genetic variants — mutations– associated with Marek’s disease virulence.
The study, published recently in the Journal of General Virology, also revealed that high virulence strains collected from the same farms in the last three years and in the 1990s were nearly identical. This illustrates the ease with which virulent Marek’s disease viruses can persist and spread between flocks as well as the difficulty in eradicating the disease from a farm once established, Dunn said.
