Ten viral genome regions may explain why deadly chicken virus evades vaccines
A highly contagious herpes virus causes Marek's disease, a deadly illness that mainly infects chickens. While it does not make people sick, the virus causes tumors and paralysis in chickens and, if unchecked, can spread rapidly through entire flocks.
A highly contagious herpes virus, Marek's disease, causes tumors and paralysis in chickens, and has evolved to evade vaccines despite widespread vaccination efforts. Researchers at Penn State and the USDA have identified 10 regions in the virus's genome that likely contributed to the increased virulence. The team sequenced the genomes of 65 different strains of the virus collected between 1962 and 2016, finding nearly 800 sites with genetic differences, including several where segments of DNA were inserted or deleted.
By building a family tree of the virus strains, the researchers discovered that all highly virulent strains shared a common ancestor, indicating a mutation or set of mutations allowed them to break through vaccine protection. A genome-wide association study (GWAS) then identified 10 genomic variants associated with increased virulence, including a type of DNA variant called a tandem repeat.
The findings could help inform the development of next-generation vaccines capable of preventing future breakthroughs.
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