A new strategy for controlling Marek's disease in poultry is to develop a line of chickens which are genetically resistant to the effects of the virus, and genetic markers may be a tool in controlling the virus, according to research completed by the U.S. Poultry & Egg Association and the U.S. Department of Agriculture's Agricultural Research Service Avian Disease and Oncology Laboratory.

The disease is currently controlled by routine vaccination of commercial broilers, breeders and layer chickens, but because the Marek's disease viruses are constantly evolving, new vaccines need to be continually developed to control bird losses. Research was conducted to: identify single nucleotide polymorphisms (structural units of DNA) in susceptible chicken lines which are associated with Marek's disease susceptibility, and identify alternative units conferring resistance. A total of 57,636 single nucleotide polymorphisms were screened and 172 units located on chromosomes 1, 3, 15 and Z were found to be possibly associated with the disease.

One of the 172 single nucleotide polymorphisms was identified at the same gene location as the susceptible allele and as the resistant allele. These results suggest eliminating a susceptible gene in breeding programs may be helpful in the control of Marek’s disease. According to researchers, primary breeding companies may use this new research to genetically select commercial chicken lines with enhanced resistance to Marek's disease.