Koala cancers associated with the spread of retroviruses through the genome – Courthouse News Service

Researchers have studied the association between koala retrovirus and higher cancer incidence in the northern Australian population.

(CN) — 8% of the genome is composed of RNA inserted by a retrovirus millions of years ago.Studies published in the journal Nature Communications On Friday, we will use a relatively recent infection of koalas with the KoRV retrovirus to understand the relationship between these DNA-modified parasites and the spread of cancer between their hosts.

Retroviruses such as HIV and KoRV can insert their RNA into the host’s DNA and pass it on for generations. Eventually, endogenous retroviruses can become fixed and inactive within the population.

Scientists hypothesize that genomic disruption caused by the insertion of a retrovirus increases the incidence of cancer. This idea is supported by studies of laboratory rats, but it remains difficult to gather evidence that this is happening in the wild.

Koalas began to infect koalas within the last 50,000 years and slowly spread from the north to the south. Today, all koalas in Queensland and New South Wales, Australia are believed to carry the retrovirus. Koala retrovirus strains are associated with common cancers in koalas, including lymphomas that infect 3% of northern koalas and lymphoid neoplasms that infect 7%.

“Each koala has an inherited copy of about 80-100 of KoRV in its genome,” research author Alex Greenwood explained in a statement. “Most of these genomic positions are not shared between koalas, indicating the rapid expansion and accumulation of KoRV copies in the population.”

Greenwood, Head of Wildlife Diseases Division Leibniz Zoo Wildlife Research Institute In Germany, “every time a retrovirus copies itself and reinserts it into the genome, it can cause mutations and disrupt gene expression, which can be harmful to the host.”

Of the 10 koalas studied, researchers identified 1,002 sites of infection from the retrovirus, averaging 100 per animal. Researchers have discovered retroviral genes in both healthy tissues and tumors.

An international team of researchers has also identified “hotspots” in the koala genome. Here, the retrovirus was inserted into a region that normally contains genes associated with cancer.

“All koalas in the northern population probably carry the same number of KoRV-A proviruses, and some provirus sites may pose a higher risk of cancer than other koalas,” the researchers said. Found.

“Although other factors may contribute to koala cancer, the burden of mutations with endogenous KoRV may increase the frequency of tumorigenesis and reduce the time to onset of cancer,” the study concludes. I have.

Tissues were collected from koalas checked in to a wildlife treatment center for illnesses such as tumors and wasting. In addition to assigning identification numbers to koalas, many veterinary teams also name animals. This study included tissue samples of Ralph, Elise, Lisa, Donovan, Butler, Cathy, Bonnie, Buster, and Bilbo.

The· University of Queensland Animal Ethics Commission Approved sampling of tissue from koalas. Researchers from Germany, the United Kingdom, Australia, and the United States have contributed to this study. National Institute of Medical Sciences And that National Institute of Health..