Chinese scientists have recently discovered a new antiviral mechanism that allows bacteria to resist phage infection, providing a guide for the development of related drugs in the future, according to China Pharmaceutical University (CPU).

Phages are viruses that specifically target bacteria. In recent years, researchers globally have realized that bacteria, as single-celled organisms, have acquired diverse antiviral mechanisms to defend themselves against phages.

Previous research demonstrated that bacteria infected by phages would activate their type III CRISPR-Cas system, which can damage phage genetic material and thus impede their ability to reproduce and allow the bacteria to resist infection, according to Chen Meirong, associate professor with CPU.

The recent study, conducted by a research team led by professor Xiao Yibei from this university, was based on CRISPR-Cas9 gene-editing technology -- which can serve as scissors to cut genetic material at specific locations.

"After two years of research, we discovered a new mechanism of immunity called CRISPR-CAAD, which can deplete the ATP within bacteria," said Chen.

CRISPR-CAAD can convert ATP, which is an energy source for biological activities, into toxic ITP, said Lu Meiling, associate professor with CPU, adding that this may result in phages not having the energy to proliferate, preventing them from spreading and thereby protecting the bacteria population from infection.

"Meanwhile, bacteria would enter into a state similar to dormancy. Based on biochemical analysis, we discovered that a hydrolytic enzyme called Nudix would further break down and detoxify ITP. In other words, the bacteria can gradually recover from dormancy after they clear the phages," Chen said.

This research reveals the intrinsic link between bacterial immunity and metabolism, deepens people's understanding of gene editing technology, and provides an important approach for the future development of anti-infective medications, Xiao said.

The study was on Friday published in the journal Science. 

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