University
of Otago research to better understand how bacteria and their viruses interact
and evolve will enable future studies to exploit the use of bacteria and their
viruses for potential biotechnology and health applications.
Research
led by Dr Simon Jackson and Associate Professor Peter Fineran, from the Department
of Microbiology and Immunology, investigating the function of bacteria immune
systems and what impact they have on the coevolution of bacteria and viruses
was published today in a top tier scientific journal, Cell Host and Microbe.
Viruses
infecting bacteria are called bacteriophages ("phages" for short) and
are the most abundant biological entities on the planet influencing many
aspects of our lives and the global ecosystem.
"Research
to understand more about the interactions between phages and bacteria,
particularly how bacterial CRISPR-Cas immunity functions, is being exploited
internationally in many ground-breaking biotechnological applications including
gene editing," Dr Jackson explains.
"We
think this area of research holds a lot of promise for biotechnology
applications and might also be an important consideration for the use of phages
to treat infectious diseases.
"For
example, because phages kill specific bacteria, they can be used as
alternatives to antibiotics to treat some infectious diseases and can even kill
antibiotic resistant bacteria."
Bacterial
adaptive immunity is similar in concept to human adaptive immunity. Bacteria
must first become "vaccinated" against specific phages, which
involves the bacteria storing a short snippet of viral DNA, termed a
"spacer," used to recognise and defend against future infections.
In a
previous study examining how CRISPR-Cas systems acquire spacers, the Otago
research team found that often bacteria acquire "incorrect" spacers,
known as "slipped spacers." At the time, they did not know whether
the incorrect or imprecise slipped spacers were functional.
Associate
Professor Fineran, a molecular microbiologist, says their initial observations
were surprising and showed these slipped spacers were very efficient at
boosting bacterial immunity by stimulating bacteria to acquire extra spacers
targeting the same phage. This unexpected role increases immune diversity,
which is important for bacteria to protect against the rapidly evolving phages.
"Several
groups had previously identified the occurrence of imprecisely acquired or
slipped spacers. However, no-one had previously considered whether they were
functional or what impact they might have on immunity," Associate
Professor Fineran explains.
"By
showing they are functional and can provide benefit to bacteria, we have
revealed an unexpected complexity to the evolutionary battle between bacteria
and phages."
If
in the future, researchers can determine how immunity is first gained, they may
be able to either prevent or promote it for different applications, Associate
Professor Fineran says.
"For
example, in the dairy industry for the production of cheese and yoghurt it is
beneficial for bacteria to have resistance against phages, whereas if phages
are used as antimicrobials, emergence of immunity would be undesirable -- akin
to antibiotic resistance."
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