Using genetic tools for investigating cattle diseases?

Geni Wren, Bovine Veterinarian Magazine
An international team - led by researchers at McMaster University and the University of Tubingen in Germany - has sequenced the entire genome of the Black Death, one of the most devastating epidemics in human history, according to a press release from McMaster University, Ontario, Canada. (Read the full press release here. )
This marks the first time scientists have been able to draft a reconstructed genome of any ancient pathogen, which will allow researchers to track changes in the pathogen's evolution and virulence over time. This work - currently published online in the scientific journal Nature - could lead to a better understanding of modern infectious diseases.
The comprehensive team described a novel methodological approach to pull out tiny degraded DNA fragments of the causative agent of the Black Death, and showed that a specific variant of the Yersinia pestis bacterium was responsible for the plague that killed 50 million Europeans between 1347 and 1351.
One of the lead authors, Johannes Krause, said, “Using the same methodology, it should now be possible to study the genomes of all sorts of historic pathogens. This will provide us with direct insights into the evolution of human pathogens and historical pandemics."
“Digging” into cattle
This type of scientific investigation into “old” pathogens may one day be useful for investigating livestock diseases. Chris Chase, DVM, PhD, South Dakota State University, says this “reconstruction” approach was first used for reconstructing influenza from the remains of Eskimos who died from the 1918 influenza outbreak.
“Of course the genome of Yersinia pestis is much larger,” Chase says. “I could see that it could have big effects on cattle diseases that have been with us for a long time, pathogens like brucellosis and tuberculosis, and how they have changed under vaccine pressure from their ancestors. That can that help us to design new vaccines.”
Another area would be to look at “normal” non-disease producing viruses in “ancient cattle digs” like some of the Herpesviruses of cattle, Chase adds. Most every species has its own Herpesviruses; cattle have five. “Infectious bovine rhinotracheitis (IBR) was not recognized as a clinical entity until the 1950s,” Chase explains. “What changed in the non-disease IBR virus to make it become a pathogen? One then could see if those new or different viral genes would be good targets for vaccines or preventive therapies.”
Bovine viral diarrhea virus (BVDV) would be even more fascinating as a clinical entity in cattle, as it was first recognized in the 1940s, Chase says. “There are not naturally occurring pestiviruses in cattle. BVDV likely came from sheep or maybe swine since border disease in sheep and classic swine fever virus have been around for hundreds of years.”
Chase says looking at “ancient sheep and swine digs” to see how these early virus progenitors of BVDV have evolved may give us insight on new vaccine targets to approach.
Major technical advances in DNA recovery and sequencing have dramatically expanded the scope of genetic analysis of ancient specimens, the McMaster press release says, which in turn is opening new horizons in the understanding of emerging and re-emerging infections.
Let’s hope veterinary science can use this information to study those diseases that plague our livestock.


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