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Bacteria 'talk' to boost immune systems

NZ NewswireNZ Newswire 22/11/2016

Bacteria can boost their own immune systems by "talking" to each other, research from the University of Otago shows.

The findings by a team led by Associate Professor Peter Fineran, from the Department of Microbiology and Immunology, appear in the international journal Molecular Cell.

Assoc Prof Fineran says that, in the same way that humans are susceptible to viruses like influenza and measles, bacteria also need to defend themselves against viruses.

He says humans have evolved sophisticated immune systems that enable their bodies to fight viral infections.

"Amazingly, bacteria - although single celled organisms - often possess similar adaptive immunity called CRISPR-Cas systems," he said.

"But the way that these CRISPR-Cas systems function is very much different to our own immune systems."

Assoc Prof Fineran said people had long understood the advantages of living in communities and bacteria were no different, often residing in close quarters to share resources.

However, there are also potential drawbacks, as high-density bacterial populations are more vulnerable to the spread of viruses - "just like people in a crowded bus or a daycare centre".

The researchers discovered that the ability to gauge the number of cells in their communities enabled the bacteria to boost the power of their CRISPR-Cas systems to prevent viral outbreaks.

Associate Professor Fineran said the bacteria sensed the population density by "talking" to each other using a form of chemical communication known as quorum sensing.

"The higher the population density, the stronger the communication between cells becomes, which results in greater co-ordination of immune defences," he says.

Adrian Patterson, a PhD student and first author on the paper, said the study showed that bacterial cells preemptively elevated their immunity when they were most at risk of a virus spreading through the population.

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