A study found that koala bears, native Australian marsupials, are infected with a virus that's integrating itself with their DNA and triggering cancer.
Despite a diet that only included eucalyptus, koala bears are facing a wide range of health issues including lymphoma, leukemia, and chlamydia. Furthermore, koala populations are facing grave threats from habitat loss and wildfires.
Despite chlamydia in koala bears have been a long-standing fact, scientists are still baffled by the mysteries of koala cancers and STDs.
Studying STDs in Koalas and Their Elevated Cancer Rates
A study published in the journal Nature Communications entitled, "Retroviral integrations contribute to elevated host cancer rates during germline invasion," analyzed DNA samples from 10 koalas, finding retroviruses embedded in their genome sequences. Wherein the most common human retrovirus, HIV was found.
The research headed by Leibniz Institue for Zoo and Wildlife Research, Berlin identified a genome-altering virus that has infected koala cells that create egg and sperm cells, unknowingly passing the virus down through the generations.
Koala retrovirus or KoRV has been found to insert itself in genetic 'hot spots' near genes associated with cancer. Researchers believe that the mutations brought by KoRV increase the prevalence of specific cancers in koala bears.
Mysteries of the Koala Retrovirus
Ancient remains of retrovirus infections are commonplace in vertebrate genomes. These relics indicate infections have occurred millions of years ago and have been neutralized by evolutionary means.
On the other hand, the recent close analysis on 10 cancer-riddled koala bears from the wild reveals that marsupial populations were only first infected with koala retrovirus roughly 50,000 years ago.
Since it has spread and can now be found in every koala genome in Queensland and New South Wales.
According to researchers, DNA samples gathered showed that every koala inherited roughly 80-100 genome copies of KoRV.
Meanwhile, Alex Greenwood, head of the wildlife disease at Leibniz-IZW explains that the genomic location of KoRV is not shared between koalas which indicates rapid expansion and accumulation of koala retrovirus within the koala population.
He adds that every time that the retrovirus copies and re-inserts itself into the koala's genome sequences it causes mutations that disrupt the bear's gene expression which scientists see as a detrimental threat to koala populations.
As the virus spreads in each koala bear it rewrites more of the host's genome thereby replacing its original DNA sequences.
The analysis suggests that KoRV predisposes koalas to specific tumors where cancer-triggering genes can be passed down to their offspring and so on.
Scientists stress that with the vulnerability of koalas already in a battle to survive as a species, surviving long enough to degrade the virus should be the priority.
Greenwood says that koala populations are continuously struggling with multiple health issues and environmental threats. Habitat loss due to last year's deadly bush fires, dog attacks, and road accidents aside koala populations are also suffering from deadly chlamydia infections with extremely high rates of cancer.
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