Immunity system complexity: how bacterial ssytem works (Introduction)

by David Turell , Thursday, June 02, 2022, 20:10 (693 days ago) @ David Turell

Stealing bits of DNA from viruses:

https://phys.org/news/2022-06-bacteria-viruses.html

"In bacteria, CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) works by stealing small pieces of DNA from infecting viruses and storing those chunks in the genes of the bacteria. These chunks of DNA, called spacers, are then copied to form little tags, which attach to proteins that float around until they find a matching piece of DNA. When they find a match, they recognize it as a virus and cut it up.

"Ideally, spacers should only match DNA belonging to the virus, but there is a small statistical chance that the spacer matches another chunk of DNA in the bacteria itself. That could spell death from an autoimmune response.

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"Balancing this risk can put the bacteria in something of an evolutionary bind. Having more spacers means they can store more information and fend off more types of viruses, but it also increases the likelihood that one of the spacers might match the DNA in the bacteria and trigger an autoimmune response.

"Balasubramanian, along with coauthors Hanrong Chen of the Genome Institute of Singapore and Andreas Mayer of University College London, realized that the bacteria could get around this by having longer spacers. Similar to how a longer password might be harder to crack, a longer spacer would be less likely to match with the DNA of the bacteria itself. This means that bacteria with longer spacers would be able to have more spacers overall without the risk of triggering an autoimmune response.

***

"The researchers found a consistent, tight relationship between spacer length and number of spacers.

"'The surprise to me is that it matched so darn well just coming out of the box," says Balasubramanian. "This is a very simple theoretical framework. There's a risk of autoimmunity, but it's nice to have more immune memory, and you must balance these two considerations. It's just very, very rare that something so simple matches the data.'" (my bold)

comment: An amazing ssytem that bacteria comntain. Note my bold. IIt fits teh possibioity the system was designed.