Viruses are the most common source of DNA and RNA on earth. A groundbreaking study of the virosphere of the most populous animals
- those without backbones such as insects, spiders and worms and that
live around our houses - has uncovered 1445 viruses.
This suggests that people
have only scratched the surface of the world of viruses - but it is
likely that only a few cause disease.
‘Viruses have been associated with invertebrates for potentially billions of years and invertebrates are the true hosts for many types of virus.’
The meta-genomics research, a collaboration between the University
of Sydney and the Chinese Center for Disease Control and Prevention in
Beijing, was made possible by new technology that also provides a
powerful new way to determine what pathogens cause human diseases.
Professor Edward Holmes, from the Marie Bashir Institute for
Infectious Diseases & Biosecurity and the School of Life and
Environmental Sciences, who led the Sydney component of the project said
although the research revealed humans are surrounded by viruses in our
daily lives, these did not transfer easily to humans.
"This groundbreaking study re-writes the virology text book by
showing that invertebrates carry an extraordinary number of viruses -
far more than we ever thought," Professor Holmes said.
"We have discovered that most groups of viruses that infect
vertebrates - including humans, such as those that cause well-known
diseases like influenza - are in fact derived from those present in
invertebrates," said Professor Holmes, who is also based at the
University's multidisciplinary Charles Perkins Center.
The study suggests these viruses have been associated with
invertebrates for potentially billions of years, rather than millions of
years as had been believed - and that invertebrates are the true hosts
for many types of virus.
The paper, "Redefining the invertebrate RNA virosphere," is published tonight in Nature
The findings suggest viruses from ribonucleic acid, known as RNA -
whose principal role is generally to carry instructions from DNA - are
likely to exist in every species of cellular life.
"It's remarkable that invertebrates like insects carry so very many
viruses - no one had thought to look before because most of them had not
been associated with human-borne illnesses."
Although insects such mosquitoes are well-known for their potential
to transmit viruses like zika and dengue, Professor Holmes stressed that
insects should not generally be feared because most viruses were not
transferable to humans and invertebrates played an important role in the
Importantly, the same techniques used to discover these invertebrate
viruses could also be used to determine the cause of novel human
diseases, such as the controversial 'Lyme-like disease' that is claimed
to occur following tick bites.
"Our study utilized new techniques in meta-genomics, which we are
also using to provide insights into the causes of human-borne diseases,"
said Professor Holmes, who is also a National Health and Medical
Research Council Australia Fellow.
"The new, expensive technologies available to researchers which have
allowed us to do this landmark project, provide the ultimate diagnostic
Professor Holmes and his collaborators are conducting human studies
using these new techniques to analyze Lyme-like disease and other