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A new study by researchers at UMass Medical School and the University of Queensland in Australia examining a retrovirus in koala bears reveals new insights into the genetic evolution of vertebrates, according to media reports in the New York Times and STAT.

“What [koalas] are going through is the process of what’s driven the evolution of every animal on the planet,” said William E. Theurkauf, PhD, professor of molecular medicine at UMass Medical School and a corresponding author of the study, in an Oct. 10 .

Over time, viral infections have led to major evolutionary changes, he said.

“A gene that is absolutely essential for the placenta was derived from the shell of a virus millions of years ago,” Dr. Theurkauf explained in the Times.

The study, , identifies a never-before-seen type of immune response. Koalas use a novel genetic defense system to fight off infection through retroviruses, a system identified when scientists focused on KoRV-A, a retrovirus sweeping through the koala population of Australia. This novel genetic response controls the production of the virus in the koala’s germline, a previously undescribed mechanism comparable to the innate immune response well-known in mammals.

Zhiping Weng, PhD, the Li Weibo Chair in Biomedical Research, professor of biochemistry & molecular pharmacology, director of the Program in Bioinformatics & Integrative Biology at UMass Medical School and a co-corresponding author of the study, said retroviruses like KoRV replicate by inserting their genome into the DNA of an infected cell. If they infect germ cells, the DNA they’re embedding into is the germline, and the viral DNA can potentially catch a ride into future generations.

“It’s almost like carbon dating,” Dr. Weng explained, in the Oct. 10 STAT story. “You can tell the sequences are old because they pick up a lot of defective pieces, so they don’t work.”

Learn more in the coverage, below.

Related story on UMassMedNow