An international team of microbiology and immunology researchers have made a microscopic discovery which could have big implications for safer gene editing, and more efficient alternatives to antibiotics.
The research team, led by University of Otago microbiologist and immunologist Prof Peter Fineran and University of Copenhagen microbiologist Dr Rafael Pinilla-Redondo, have discovered a new way that viruses suppress the CRISPR-Cas immune systems of bacteria.
Prof Fineran said viruses had created anti-CRISPRs which acted as decoys, ruining the defences of bacteria.
The discovery would not only enable scientists to understand the microbial world around us, but could also provide a new way to control CRISPR-Cas biotechnologies.
Co-author and fellow Otago researcher Dr David Mayo-Munoz said the finding could teach us about microbial dynamics in the environment, be used to make gene editing safer and lead to more efficient alternatives to antibiotics.
"The discovery is exciting for the scientific community because it provides a greater understanding of how CRISPR-Cas defences can be stopped."
CRISPR-Cas were immune systems that bacteria had, he said.
They protected the bacteria from getting infected by bacterial viruses, called phages.
It worked by taking pieces of phage DNA and adding it to the bacterium’s genome.
Bacteria ended up with a memory bank of past phage infections, which it filed like "mugshots", using them to identify and degrade that specific phage when it attacked again.
"If a virus comes in, part of its DNA is added to the memory bank, and then turned from DNA to RNA in the process," he said.
"Each RNA acts like a guide, so the CRISPR-Cas system can correctly identify and destroy the invading phage.
"Each addition to the memory bank is divided by a CRISPR repeat sequence, which stacks up like bookends between each phage sequence.
"The interesting thing is that phages have evolved different ways to overcome these defence systems — it’s like an evolutionary arms race."
