Sperm and egg cell 'immune response' protects koala DNA

October 14, 2019

Discovery of a type of immunity that protects koalas' DNA from viruses has importance for the survival of koalas and our fundamental understanding of evolution.

A team of scientists from The University of Queensland and University of Massachusetts Medical School are studying tissue samples from koalas to understand how a unique type of cell responds to retrovirus infections, which cause diseases such as chlamydia and cancer.

According to Dr Keith Chappell from UQ's School of Chemistry and Molecular Biosciences, discovery of this unique immune system response could open a whole new field of research.

"The genomes of all animals, including humans, contain a large amount of viral sequences that are the result of infections that occurred millions of years ago," Dr Chappell said.

"The koala is the only species in which a retrovirus is known to have recently infected the germline cells - the ones that make sperm and eggs.

"This means that some koalas are born with koala retrovirus A - known as KoRV-A - in their genome, making them more susceptible to diseases such chlamydia and cancer."

It is well known that viruses have driven the evolution of humans and animals over thousands of years, yet understanding how germline cells respond to infection has been a mystery for scientists.

"It was previously thought that the process of natural selection kept levels of viral elements in check within the genome, meaning that it would be survival of the fittest for the koala," Dr Chappell said.

"However, our findings show that there are immune response like pathways within a koala's germline cells that can actively fight back against the invading virus."

Professor William Theurkauf from UMass Medical School said the germline cells of koalas could distinctly recognise the unique sequence of KoRV-A as an "invading virus" and not a gene, and would mount an initial defence.

"Just like the human body launches an immune response to invading viral and bacterial infections, our findings suggest that germline cells mount an attack to chop up the viral sequences," Professor Theurkauf said.

"This prevents the retrovirus from inserting more and more copies into the genome of the offspring and thereby protects the next generation against what would be compounded effects of disease."

The research findings are published in Cell (DOI: 10.1016/j.cell.2019.09.002).
The study was supported through funding from the USA's National Institute of Health, the Australian Research Council and the Chinese National Natural Science Foundation.

University of Queensland

Related DNA Articles from Brightsurf:

A new twist on DNA origami
A team* of scientists from ASU and Shanghai Jiao Tong University (SJTU) led by Hao Yan, ASU's Milton Glick Professor in the School of Molecular Sciences, and director of the ASU Biodesign Institute's Center for Molecular Design and Biomimetics, has just announced the creation of a new type of meta-DNA structures that will open up the fields of optoelectronics (including information storage and encryption) as well as synthetic biology.

Solving a DNA mystery
''A watched pot never boils,'' as the saying goes, but that was not the case for UC Santa Barbara researchers watching a ''pot'' of liquids formed from DNA.

Junk DNA might be really, really useful for biocomputing
When you don't understand how things work, it's not unusual to think of them as just plain old junk.

Designing DNA from scratch: Engineering the functions of micrometer-sized DNA droplets
Scientists at Tokyo Institute of Technology (Tokyo Tech) have constructed ''DNA droplets'' comprising designed DNA nanostructures.

Does DNA in the water tell us how many fish are there?
Researchers have developed a new non-invasive method to count individual fish by measuring the concentration of environmental DNA in the water, which could be applied for quantitative monitoring of aquatic ecosystems.

Zigzag DNA
How the cell organizes DNA into tightly packed chromosomes. Nature publication by Delft University of Technology and EMBL Heidelberg.

Scientists now know what DNA's chaperone looks like
Researchers have discovered the structure of the FACT protein -- a mysterious protein central to the functioning of DNA.

DNA is like everything else: it's not what you have, but how you use it
A new paradigm for reading out genetic information in DNA is described by Dr.

A new spin on DNA
For decades, researchers have chased ways to study biological machines.

From face to DNA: New method aims to improve match between DNA sample and face database
Predicting what someone's face looks like based on a DNA sample remains a hard nut to crack for science.

Read More: DNA News and DNA Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.