Over the last few years, plenty of buzz has generated around CRISPR, the gene-editing technique at the center of the ethical debate of its use on human genomes. However, CRISPR isn't all that new - bacteria have their own version of the technique that they invented billions of years ago against dangerous viruses and now, a new study from Aix-Marseille University researchers reveals that even viruses have their own version.
The bacteria use their unique CRISPR system to take hold of pieces of a virus' genetic material and integrate them into their own DNA, allowing them to remember the identity of past viruses and use their genetic sequences to increase the efficiency of their own defensive enzymes.
The current study shows that this system is used by viruses in order to protect themselves against smaller viruses by stealing the genes of their attackers in order to increase their countermeasures, much in the same way as bacteria do.
In the study, the team analyzed the genomes of 60 strains of mimiviruses in order to locate snips of DNA that originated from a smaller virus called Zamilon. Just as they expected, they found bits of the Zamilon genetic code in the mimiviruses, as well as enzymes that have the ability to degrade foreign DNA just like CRISPR.
Although the virus CRISPR, which the team called MIMIVRE, isn't the exact same as its human counterpart, it is still fairly close and is a great example of convergent evolution, the process whereby two different groups of living things come up with the same solution to the same problem independent of one another.
The results will hopefully help researchers better understand the underlying mechanisms of MIMIVRE and also throw some wood into the fire of the discussion on what it takes to be considered "alive."
"[Some giant viruses] can get sick from a viral infection and can produce a 'immune' response to the infection," said Chantal Abergel, a scientist who explores the genetics of viruses and virophages. "Again, this blurs the frontier between viruses and cells and ask for reconsideration of what should be considered as alive."
